ft.
"N*
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"This very good book is friendly, well thought out and contains
interesting information. It also takes a unique point of view that could be
very useful for learning about systems and interactions."
Dr. Goery Delacote
Executive Director, Exfloratorium, San Francisco
"This is a superb primer on the web of life. My hope is that every
child who reads it entice their parents to read it too, in hopes that adults
will join the children in understanding we have only one precious web of
life on Earth."
Paul Hawken
Author, Chairman, The Natural Step, US
Founder, Smith and Hawken
"What a wonderfully concise and brilliandy simple presentation! As
an environmental science educator for 20 years, I'm glad to have such a
user-friendly teaching tool. Highly recommended for all Earthlings!"
Carol Fialkowski
Field Museum of Natural History, Chicago
"I have used Dr. Art's ideas to teach teachers and to teach high
school students. Both groups love his approach. They develop a deep
understanding of how our planet works, and they enjoy themselves as
they learn."
Teresa Hislop
Utah Mentor Science Teacher
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DR. ART'S
Tl
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Dr. Art's Guide to Planet Earth
Dr. Art's Guide to Planet Earth
©2000 WestEd, 730 Harrison Street, San Francisco, CA 94107
Design: Susan M. Young
Illustration: Emiko-Rose Koike
Library of Congress Cataloging-in-Publication data is available.
Please contact Chelsea Green Publishing Company at 1-800-639-4099.
Photos courtesy o£
Artville: pp. 36, 100; Corbis Images: pp. 80, 81; Eyewire: cover, pp. i, 5, 6, 9, 10, 15, 26, 41, 43, 44,
53, 60, 71, 75, 77, 79, 83, 88, 96, 99, 102,103, 104, 106, 109, 114; Masterphotos; pp. 1, 8, 11, 13,
14 15 17 18,19,20, 24, 31, 33, 43, 46, 47, 50, 51, 75; NASA: pp. 1, 2, 3, 17, 78, 90; Photodisc;
cover, pp. i, iii, 5,19, 21, 29, 34, 35, 45, 54, 55, 60, 63, 66, 68, 74, 75, 77, 79, 80, 83, 84, 87, 99,
102,111,115.
Tables reprinted from pp. 51 and 85 from The Consumer's Guide to Effective Environmental Choices
by Michael Brower and Warren Leon, copyright © 1999 by the Union of Concerned Scientists.
Reprinted by permission of Harmony Books, a division of Random House, Inc.
ISBN: 1-890132-73-X
ii
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Contents
EARTH
CHAPTER 1 •
Farth M/Vhnlp
Systems within Sysfpms within Sy^tpm^
The Farth Sysfpm
Farth'<; Mattpr
Farth's Energy
Farth'Q 1 ifp
Thrpp Prinnp|p<;
Ronk Overview
i
/,
K
in
1-7
1/1
16
17
CHAPTER 2 -
Earth's Solid Stuff.
The Rock Cycle
The Water Cycle
Earth's Gas Stuff
The Carbon Cycle
Today's Carbon Cycle.
es
.28
-34
ENERC3Y
CHAPTER 3 -
\y Flows
; Energy
Part of a
Energy from the!
The Greenhouse I
Earth's Internal Energy.
Earth's Energy Budget _
-48
-50
-54
-56
iii
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Dr. Art's Guide to Planet Earth
CHAPTER 4 - Lire Webs
A 1 ivin** Pl^nft
Wntrhin°r Farth Rrpnthp
Wh" i« i" *hp Wph?
Ecosystems and Fp°dhrirk ' nnp<:
qhrpHHin«rthpWph
60
62
f>f>
68
74
CHAPTER 5
- Think Global!
Save the Planet?-
Extinction
The Ozone Layer-
Climate Change -
Ice Age or Hot House?-
CHAPTER 6 - Act Locally
Healthy Air, Water & Food .
The Three R's :
Local Ecosystems
What About Energy?
What Can I Do?
Making a Difference
Not the End
.78
.80
.86
.92
.96
.100
.102
.104
.106
.108
. 112
.116
iv
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Dr. Art's Guide to Planet Earth
earth Ls.
One of humanity's major discoveries is that we live on a
round planet We laugh about the idea that Earth is flat
Yet, we ourselves are in the midst of an even greater change
in how to understand our planet And most of us don't
know about it
When we realized that Earth is round, we learned how the places on
our planet are physically connected to each other. We discovered
that if we kept traveling in one direction, we would not fall off the
edge. Instead we could go in a circle and return to our starting place.
That was an important discovery for our ancestors.
Now we are learning something much more important than how the
places on our planet are physically connected. We are discovering
how Earth works as a whole system. Earth is not flat. Earth is much
more than round. Earth is whole.
"Earth is Whole" means that all the planets physical features
and living organisms are interconnected. They work together in
important and meaningful ways. The clouds, oceans, mountains,
volcanoes, plants, bacteria and animals all play important roles in
determining how our planet works.
Scientists have established a new field of science called Earth systems science
to study and discover how all these parts work together. Earth systems
scientists combine the tools and ideas from many scientific disciplines
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Introducing Planet Earth
including geology, biology, chemistry, physics and computer science. In
addition, they use modern technologies to measure key features of our
planet, such as the concentration of gases in the atmosphere and the
temperature of the ocean in many locations. Satellites orbiting our planet
provide enormous amounts of data that Earth systems scientists use to try to
understand how our planet works and what kinds of changes are happening.
Of course, human beings do more than study and measure planet Earth.
Just like any other organism, we are a part of this whole Earth system. More
importandy, we now have a very challenging new role to play. For the first
time in our history, we can dramatically change the way the planet works as a
whole. There are so many of us and we have such powerful technologies that
we can change Earth's climate, destroy its ozone shield and dramatically alter
the number and kinds of other organisms that share the planet with us.
Over the past five years, I have developed a method of explaining Earth
systems science to my family, friends, co-workers, teachers and students.
I also perform a show where I use scientific demonstrations and audience
participation to introduce the three Earth systems principles that are
featured in this book. My experience is that people enjoy learning about
Earth systems science, and they feel they get a better perspective on how
our planet works and what they can do as local and global citizens.
Dr. Art's Guide to Planet Earth helps answer one of the most
important questions of the twenty-first century: Can all of
us live well on our planet without damaging the whole
Earth system? To answer this question, we need to
understand how our planet works. That sounds much
more complicated than discovering that Earth is
round. Fortunately, Earth systems science can
explain many of the most important features of how
our planet works.
1
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Dr. Art's Guide to Planet Earth
systems within
J .fm* 4h m ^^» *•• ^S^^ k^M^i^k ^^"
reins witnin . i .
systems within systems
The first step toward understanding how Earth works is to
think about our planet as a system. We use the word "system"
when we want to describe something that is made up of
different kinds of parts that join together to form an
interconnected whole. Learning to think in terms of systems
is very useful because we are surrounded by all sorts of
systems. In fact, each of us is our own little system.
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Introducing Planet Earth
Each of us is made up of more than 200 kinds of cells. These nerve, skin,
muscle, bone, red blood and gland cells all join together to form an
incredible system — an individual human person. All the structures that
these cells form — our skin, muscles, bones, blood vessels, internal organs —
function as an interconnected whole.
Looking at ourselves as a system reveals two important features of systems:
• each part oF a system can itself be described as a system;
9 a system can be very different from its parts.
Each part of a system can itself be described as a system. You are a
system. One of the parts of the "you system" is the way blood moves
throughout your body — in other words, your circulatory system. This
circulatory system is part of the bigger "you system" but it itself is a system
with many parts.
The parts of the circulatory system include heart, veins, arteries
and blood cells. The heart, a part of the circulatory system, is
also a system made of parts. Its parts include muscle cells,
|||:nerve cells and valves. A heart muscle cell is part of the
llijt system but it is also a system that is made up of a cell
, cell nucleus and many different proteins.
1
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Dr. Art's Guide to Planet Earth
You could get dizzy visualizing all these systems
within systems within systems that are inside
each one of us. And die story does not end
with us. "We are not the biggest system
around. Each of us systems is, in turn,
part of many larger systems. Each of
us is part of a family system. Each of
us is part of an ecosystem. Each of us is
part of an entire human system that is part
of the system of life on this planet.
Why should we care about all these systems within systems within
systems? The second system feature that we mentioned earlier
provides an important clue.
A system can be very different from its parts. Think about your
arteries, red blood cells, stomach and toenails. Your stomach is a part
of who you are, but you are much more than your stomach. You are
much more than the sum of your parts. As a functioning, intercon-
nected whole, you have characteristics that do not exist in any of
your parts. You have properties that transcend, that go far beyond,
the qualities of your parts.
A car provides another example of a system. A car has brakes, wheels,
cylinders, battery, windshield wipers, carburetor, gas tank, metal frame,
steering wheel, and hundreds of other parts. Individually none of those parts
will move you from your home to school, work, a restaurant or a lake.
Joined together as an interconnected whole, the car system can take you
away. It has properties that are qualitatively different than the properties of
its parts. No part of a car gets 35 miles per gallon on the highway. No part
of a car has the ability to transport you up a mountain road. Only the car as
a functioning whole system has these properties.
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Introducing Planet Earth
The popular saying "the whole is more than the sum of its parts" describes
this second system feature. This popular saying is much deeper than it
might first appear. When we say that the whole is more than the sum of its
parts, we mean that the whole system has qualities that are different than
those of the parts. The whole is qualitatively different, which is a much
more important difference than a mere increase in quantity.
Hydrogen
Oxygen
Take water as another example of a system. Water is made of hydrogen and
oxygen. At normal temperatures and pressures, they are both gases.
Hydrogen is highly explosive, and fires require oxygen. Put them together
and you have a liquid that extinguishes fires. The system of hydrogen joined
with oxygen (H2O) has properties that are qualitatively very different from
the parts hydrogen alone or oxygen alone.
7
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Dr. Art's Guide to Planet Earth
h P parth
system
smog
DDT?
Many of us feel overwhelmed by the environmental issues
that we encounter in newspapers and magazines, or on
television, radio or the Internet We see weird combinations
of letters like PCS and CFC. We read
statements from opposing Ph.D.
experts, one of whom says that global
warming is a serious problem while the
other tells us we have nothing to worry
about. How can we understand these
complicated environmental issues?
The reason to care about "systems within systems within systems" is
that systems thinking provides us with a way to understand any
particular system, especially complicated ones like planet Earth.
The system could be a person or your circulatory system or a car
or planet Earth. No matter what the system is, we can always
understand it better by asking three systems questions.
What are the parts oF the system?
How does the system Function as a whole?
How is the system itselF part oF larger systems?
8
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Introducing Planet Earth
Dr. Art's Guide to Planet Earth uses systems thinking to
help us understand how our planet works and how we can
support the way our planet currendy operates. We will learn
three guiding principles that can provide a framework for our
thinking. These principles help us focus on major concepts
rather than becoming lost in confusing details. They provide
a framework to guide our actions as individuals, local
communities, nations and a global species. We begin with the
first systems question: What are the parts of the Earth system?
To understand how our planet works, I believe it is best to
describe the Earth system in terms of die following three parts:
° Earth's matter
• Earth's energy
• Earth's liPe
In examining Earth as a whole, we are
going to focus on Earths matter, Earth's
energy and Earth's life. In other words,
we are going to examine from a systems
point of view the stuff (matter) that
exists on planet Earth, the energy diat
makes things happen on planet Earth,
and the organisms that make our
planet unique in the solar system.
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Dr. Art's Guide to Planet Earth
earth's
nfatter
Our planet has been circling the sun for more than four
billion years. During those billions of years, the matter on our
planet keeps changing its form. Water evaporates from the
ocean, forms clouds and falls as snow and rain. Rocks get
broken down into dirt that is washed as sediment into rivers.
Plants take carbon dioxide gas from the atmosphere and
convert it into solid sugars and starches. Why doesn 't all the
ocean water turn into mountain snow, or all the rocks turn
into sediment or all the atmospheric carbon dioxide turn
into sugar?
Earth still has oceans, mountains and atmospheric carbon dioxide because
they are part of cycles — the water cycle, the rock cycle and the carbon cycle, j
Water flows in rivers back to the oceans; buried sediments reach the surface j|
again through volcanoes; and animals chemically change sugars into carborjf
dioxide that goes back into the atmosphere.
Earth is a recycling planet. Essentially all the matter on Earth has been
since the planet was formed. We don't get new matter; old matter does r|
go away into outer space. The same matter keeps getting used over and'|
again. From a systems point of view, we say that Earth is essentially a c
system with respect to matter.*
* Of course, Earth is not a totally closed system with respect to matter. For example, we are constantly
bombarded by meteorites. Yet, the total amount of matter that has entered the Earth system during the
past three billion years is less than 0.00001% of Earth's total mass.
10
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Introducing Planet Earth
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Dr. Art's Guide to Planet Earth
earth's
energy
Imagine what would happen if the sun stopped shining!
This disastrous scenario emphasizes the crucial role of solar
energy. Our planet relies on a constant input of energy from
the sun. Earth receives an inflow of solar energy that is more
than 15,000 times the amount of energy consumed by all
human societies. This constant flow of solar energy into the
ft
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Introducing Planet Earth
If Earth retained all that energy, it would become so hot that it would just
boil away. But energy does not stay in any one place. Energy flows away
from Earth in the form of heat radiating to outer space. The amount of
energy radiating to outer space balances the amount of energy flowing in
from the sun.
Note the difference between Earth's matter and Earth's energy. With respect
to matter, Earth is a closed system. Matter does not enter or leave. With
respect to energy, Earth is an open system. Sunlight energy flows in and heat
energy escapes.
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Dr. Art's Guide to Planet Earth
earth's
liFe
Earth's organisms form an intricate web of interconnections,
with every organism depending on and significantly affecting
many others. As one very important example, virtually all
communities of organisms ultimately depend on plants.
Plants capture energy from the sun and store it as chemical
energy. Plants are Earth's producers.
With respect to food energy, the rest of the organisms are consumers. Some
eat plants, others eat animals that eat plants and some eat both plants and
animals. The plants, in turn, rely on animals for pollination or for spreading
seeds, and on decomposers for creating rich soil from dead waste.
With respect to life, Earth is a networked system. Not only do organisms
form an interconnected web, they also participate actively in Earth's matter
cycles and energy flows. Human beings depend on the web of life for
the air that we breathe and the food that we eat. As our numbers have
exponentially increased and our technologies have altered virtually every
part of the globe, we have become a very important part of this web of life.
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Introducing Planet Earth
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Dr. Art's Guide to Planet Earth
t h r e e
prmci
pies
We began investigating the Earth system by asking the first
system question: What are the parts of the Earth system?
Our answer focused on three parts - Earth's matter, Earth's
energy and Earth's life. The second system question asks:
How does the system function as a whole?
16
Guess what? "We have already answered that question. "When we looked at
each part of the Earth system, we learned how that part works for the planet
as a whole. As a result, we can say that there are three simple principles that
work together:
MATTER CYCLES
Each of the elements that is vital for life exists on Earth
in a closed loop of cyclical changes. From a systems
point of view, Earth is essentially a closed system with
respect to matter.
ENERGY FLOWS
The functioning of our planet relies on a constant input of
energy from the sun. This energy leaves Earth in the form
of heat flowing to outer space. From a systems point of
view, Earth is an open system with respect to energy.
LIFE WEBS
A vast and intricate network of relationships connects all
Earth's organisms with each other and with the cycles of
matter and the flows of energy. From a systems point of
view, Eardi is a networked system with respect to life.
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Introducing Planet Earth
These three principles can help us understand essentially all environmental
issues. When we confront an environmental issue, we should first explore
the roles of matter, energy and living organisms. Where does the matter
(carbon, water, pollutant) come from and where does it go? Does the issue
involve changes to our planet's energy flows? How do plants, animals and
microorganisms influence the issue and how are they affected by it? As a
result of answering these kinds of questions, we will discover that the three
guiding principles provide an organizing framework that makes common
sense out of complicated issues.
In the twenty-first century, we find ourselves in a new world.
Without meaning to, we can change the way that our planet
works. At the same time, we are developing a much deeper
understanding of the Earth system.
This chapter has introduced three principles that can help us
focus on major concepts rather than become lost in confusing
details. The next three chapters will help us understand each of
these three principles much more deeply. We will be able to explain how
Earth works in terms of cycles of matter, flows of energy and the web of life.
But merely knowing something, even something as important as how our
planet works, is not enough. We need to apply that information in our lives.
The last two chapters apply this understanding of the whole Earth system to
environmental issues that we face globally and locally. The three Earth
systems principles help us understand these issues, and diey also provide
guidance regarding what we need to do as a global species, nations, local
communities and as individuals.
Tj.
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Dr. Art's Guide to Planet Earth
lore Chapter 1 on the web
18
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Dr. Art's Guide to Planet Earth
ea
In this chapter, we are going to explore the SYSTEM of Earth's
matter. As a systems thinker, you probably began asking
yourself a systems question, such as: What are the parts of
the Earth matter system?
We can think of Earth's matter system as being made of
three kinds of parts — solid stuff, liquid stuff and gas
stuff. Scientists call these parts of the Earth matter
system its geosphere (solid), hydrosphere (water) and
atmosphere (gas). We begin with the geosphere, Earths
solid stuff.
We can hardly imagine the conditions 4,500,000,000
(four billion five hundred million) years ago when
Earth began to take shape. As a young, new planet,
Earth was an exploding ball of molten rock and metal.
Material kept crashing into and sticking to the planet,
causing it to grow larger and larger. As it eventually
stabilized in size and cooled, die densest material settled to the center
forming an iron core that causes Earth's magnetic field.
We live on a thin crust of the less dense material. This crust remained
floating on the top and solidified as it cooled. If we represent our planet as a
globe that is four feet in diameter, the crust would occupy just the top one
quarter inch.
2O
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Matter Cycles
Most of the geosphere is very different than the solid Earth that we
experience every day. Below us lies an almost completely unexplored world
of extremely hot rock and metal. This material, existing in conditions of
very high temperatures and pressures, melts and flows, descending
thousands of miles below our feet, homes, oceans and forests. Earthquakes,
volcanoes and geysers indicate the high temperatures and pressures that exist
in Earth's pressure cooker interior.
Scientists thought today's continents and oceans had been
the same for billions of years. In the 1960s, they found
convincing evidence that challenged this view of the Earth.
Their measurements, theories and data analysis changed the
way we understand our planet and caused a revolution in the
Earth sciences.
This revolution taught us that Earth's surface consists of about
a dozen huge plates that move into, away from, over, under,
and next: to each other. These plates float on top of a moving
layer of hotter, more fluid material. The oceans and continents
are contained as parts of these plates and move with them. So,
instead of staying the same for billions of years, the continents
and oceans keep changing their size and location.
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Dr. Art's Guide to Planet Earth
Look how quickly they change! Only last month (okay, 225 million years
ago - but that is last month on the geologic time scale), all the land mass
was joined together as one huge supercontinent. By the time of the Jurassic
Age (135 million years ago), some separation had occurred but Africa was
still practically joined to South America. Only in the last 135 million years
(less than 5% of Earth's existence) has the mighty Atlantic Ocean formed
between the Americas and Africa/Europe.
225 million years ago
135 million years ago
Today
22
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Matter Cycles
India provides another dramatic example of these changes. The current
Indian landmass once existed south of the Equator, near the current location
of Australia. During these hundreds of millions of years, the plate carrying
today's India moved about 4,000 miles northward. As a result, India crashed
into Asia approximately 40 million years ago and joined that continent. The
surface crust where India and Asia collide crumpled upwards, forming the
Himalayas, which includes Mt. Everest and the other nine highest peaks in
the world.
Eurasian
Plate
t—-">^ ".;-»--, -;1-.;-
Eurasian'
Plate
Pacific
Plate
yW& fSfcfc^.. •.:..-,•• .......-• ;=Sr~..-.a ..
!*5«ii^^w^t:^;-: j^r«>y^^ ••••/•
Nazca
Plate
1 South American f
Plate
This zoom view shows
that the Nazca plate and
the Pacific plate move
away from each other
as new crust emerges
and spreads in both
directions. On its
Eastern border, the Nazca
plate dives under the
South American plate.
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Dr. Art's Guide to Planet Earth
the rock
cycle
For our purposes in understanding planet Earth, we need
to realize that these plates and their movements explain
much more than continents coming together and being pulled
apart. The movements of the plates are an important part
of the rock cycle.
Rocks on the Earth's surface are continually broken down by the
forces of flowing water, chemical reactions, blowing wind and
crushing ice. This broken rock eventually washes into the ocean
as sediment. The net effect of this erosion is to lower the surface of
the continents to sea level. From the point of view of geological
time, mountains crumble rapidly. In die course of just 18 million
years, die continents would be reduced to sea level and the oceans
would cover the Earth.
Why do we still have continents and mountains that reach miles
into the air? Since the continents have existed for hundreds of
millions of years, this erosion process must be balanced by a
mountain building process. The movements of die plates explain
many details of diis mountain building.
Sometimes die mountains arise when continental masses collide, as in die
case of the Himalayas. Volcanoes demonstrate that mountains are also built
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Matter Cycles
from molten material from the Earth's interior. Lava does not just erupt on
land. The oceans have submerged mountain ranges that are among the most
geologically active regions on our planet. These are places where melted rock
constantly flows from the interior to become new crust.
Earth's surface crust is constantly eroded into the oceans, sucked deeper
into the Earth's interior and eventually rebuilt into rocks that return to the
surface. The same rock material keeps getting used over and over again.
When we explore the system of matter on planet Earth, the rock cycle is
one reason that we walk around muttering "matter cycles, matter cycles,
matter cycles."
ROCK GVCLE
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Dr. Art's Guide to Planet Earth
earth
c liquid stuFF
Water blesses our planet and makes it appear beautifully blue
from space. The presence of liquid water clearly distinguishes
Earth from all the planets and moons of the solar system. In
fact, water covers almost three times as much of Earth's
surface as land does.
Water plays such an important role in our planet that Earth
systems scientists extensively study the hydrosphere, the SYSTEM
of all Earth's water. This hydrosphere itself can be studied in terms
of its subsystem parts - the oceans, frozen water in glaciers and
polar ice caps, groundwater, surface fresh water and water vapor in
the atmosphere.
The parts of Earths water system can also be identified as "water
reservoirs," places where water occurs. (Scientists use the term
reservoir to describe the different places where any substance, not
just water, occurs). The water reservoir that holds the most water,
97.25% of all water on Earth, is the ocean reservoir. Check the
Water Reservoir table to compare the amounts in other reservoirs,
such as glaciers, groundwater, atmosphere and living organisms.
26
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Matter Cycles
We can also compare the different water reservoirs by representing all of
the Earths water as 1,000 milliliters (1 liter) in a beaker. The oceans would
contribute most of the 1,000 milliliters. In this comparison, for example,
lakes and rivers would contribute just about one drop, and the atmosphere
would be a very small part of a drop.
Of course, Earth has much more than 1,000 milliliters. The biosphere,
the smallest reservoir in the Water Reservoirs table, contains 600 cubic
kilometers.* How much water is that? Enough to fill 60,000 domed
stadiums. This means the water in all Earths plants and animals would
fill 60,000 domed football stadiums. So, we're talking about a lot
of water even in the smallest reservoir.
One cubic kilometer of water fills a cube one kilometer high, one
kilometer wide, and one kilometer deep. One cubic kilometer
equals about 260,000,000,000 gallons, enough water to fill more
than 100 domed stadiums.
o.oi atmosphere
o.i lakes & rivers •
• 6.8 groundwater
^20.5 ice
972.5 oceans
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Dr. Art's Guide to Planet Earth
t e r
e
MeetH20, a water molecule made up of two hydrogen
atoms connected to one oxygen atom. The smallest piece of
water is one molecule ofH20. About one hundred million
water molecules placed side by side would stretch all of
one centimeter.
Imagine that you are a water molecule here on planet Earth. As we have seen,
most of Earths water exists as a liquid, so you are probably part of an ocean. Yon
have more neighbors than you could possibly count. Even one drop contains an
enormous number of water molecules (about 3,000,000,000,000,000,000,000).
S(
meet a water molecule.
100 million water molecules
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Matter Cycles
You are constantly moving at speeds on the order of 50 miles per hour, but you
don't get anywhere. You are so tighdy packed with other water molecules that you
constandy crash into them and bounce away. In any given second you travel
distances thousands of times your size but it's an endless zigzag of bouncing up
and down and back and forth that leaves you very close to where you started. If
you had wanted to get anywhere (which, being a water molecule, you don't), you
would be very frustrated (good thing you are a water molecule with no desires).
Suddenly a bolt of energy that has traveled 93,000,000 miles from the sun
crashes into you. Now you find yourself traveling faster and over much greater
distances. And your neighbors have changed. Whereas before all your neighbors
were other water molecules, now most of the molecules you bump into are
nitrogen or oxygen molecules. Occasionally you smash into other water
molecules and rebound away.
Finally you realize what has happened. You have evaporated. What a gas! In fact,
you have entered the gas state. You absorbed enough solar energy to escape from
the close attraction of all those other water molecules back in your old liquid
neighborhood. Amazingly brave water molecule, you jumped out of the liquid
state into die vast unknown, into thin air.
Here on planet Earth, water molecules behave like this all the time. They
evaporate from the liquid state into the gas state. They also perform the opposite
trick. When a lot of water molecules zooming around in the gas state attract each
other, diey can stay connected as a very, very tiny drop of liquid water. They
connect with other very tiny drops and before they know it, gravity forces them
to fall to the ground in the liquid state. They have precipitated as rain or snow.
Returning now to thinking about water reservoirs on planet Earth, we see that
this evaporation and precipitation causes water to move from one reservoir to
another. A water molecule does not tend to stay trapped in the same old reservoir.
Over the course of time, it changes both its physical state (gas, solid, liquid) and
its physical location (ocean, atmosphere, glacier, river).
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Dr. Art's Guide to Planet Earth
Let's examine a reservoir in the Water Cycle illustration (page 31). For the
ocean, 434 units (each unit is equal to a thousand cubic kilometers of water)
leave per year via evaporation. However, 398 of those units return directly to
the ocean as precipitation (rain on the ocean). The remaining 36 units get
blown over to the land where they are deposited primarily as rain and snow.
If they did not return to the ocean, then the ocean would progressively lose
water. However, that is not what happens. Over the course of a year, 36 units
of water flow as runoff from the land into the ocean. The net result is that
just as much water enters the ocean as leaves it and the total volume of the
ocean does not change. The amount of water in the atmosphere also remains
constant because the amount entering equals the amount leaving.
From a long term global perspective, we see that the same water molecules
are used over and over again. The hydrosphere, planet Earth's water system,
is a closed system. No new water enters the hydrosphere. No used up water
leaves the hydrosphere. The same water keeps moving from one reservoir
to another, going round and round, leading to the name we give this
phenomenon - the Water Cycle. When we explore the system of matter on
planet Earth, the water cycle is another reason that we walk around
muttering "matter cycles, matter cycles, matter cycles."
1,370,000,00 djvifJed
by 434,000
equals 3,160 years
1*370,000,000
'cubic kf(o}fie,ters
cubit kilometers
13,000 divjded
equals a'o2'6jeafs equals
about 9 flays
cubic kilometers
1 cubic kilometers
As we have seen, the different reservoirs of the water cycle can differ greatly
in the amount of water they contain. They also differ in the rate at which it
enters and leaves. The chart above shows .that a water molecule stays in the
30
-------
Matter Cycles
ocean about 3,000 years, while it stays in the atmosphere only 9 days. The
same water cycles over and over through the various reservoirs.
To sum up, Earth's liquid stuff, its hydrosphere, exists in reservoirs that are
connected through the water cycle. These reservoirs differ greatly in their
size and the rate at which material enters and leaves them.
Water leaving atmosphere = 398 +107^505
Water entering the atmosphere=434 + 7* S
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Dr. Art's Guide to Planet Earth
Here is another way to understand the water cycle. Think about one of our
:ancestors who lived in Africa'a million years ago. Or think about a dinosaur
that lived 70 million years ago. Or consider a buffalo that roamed the
American Midwest millions of years before the arrival of humans. No matter
which you choose to bring to mind, that organism drank water throughout
its life. This water was present in every drink and in every grain, fish or flesh
that was consumed. The water molecules became part of that organism's
body and then flowed back into the world as blood, sweat, urine and
exhaled water vapor.
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Matter Cycles
Now, fill a glass with water. This glass that you hold in your
hand today has more than ten million water molecules that
once passed through the body of the buffalo, more than ten
million water molecules that passed through the dinosaur and
more than ten million water molecules that passed through
one of our African ancestors! The water that we drink connects
us intimately with the living beings that inhabited the planet
before us, that inhabit Earth today and that will inhabit it in
the future.
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Dr. Art's Guide to Planet Earth
e a r'_L_h
TufF
Earth's atmosphere is a very thin layer of air that protects
and sustains us. At the top of tall mountains, most of us
experience problems breathing due to the thinning of Earth's
atmosphere. The higher we go, the fewer the gas atoms in the
atmosphere and the more it resembles the emptiness of
outer space.
Compared to the geosphere and the hydrosphere, the atmosphere is
the most sensitive and changeable of Earths "spheres." It can
change quickly because it is comparatively very small. In terms of
mass, the whole Earth system contains a million times more solid
stuff than gas. Therefore, if a small part of Earths solid stuff
changes to gas and enters the air, it can have a major effect on
the atmosphere.
Nitrogen accounts for almost four fifths (78%) of the gas in the
atmosphere. Oxygen at 21% accounts for almost all the rest. The
rest of the gases in the atmosphere are present in much smaller
amounts, with the most important being carbon dioxide at about
0.03%. As we all experience, the atmosphere also has varying
amounts of water vapor, depending on the location and the
weather at any particular time. The same volume of warm air above a
tropical rainforest can contain a hundred times more water than the cold,
dry air over the Antarctic.
-------
Matter Cycles
I hope you will not be surprised that the nitrogen, oxygen and carbon
located in Earth's atmosphere each participate in a matter cycle. By now you
should expect that matter on Earth is used over and over again. Everything
on the planet is made of atoms and these atoms on Earth are neither created
nor destroyed. The same atoms keep combining, separating and
recombining with each other.
We will focus here on one of Earth's most important cycles, the carbon
cycle. Since all Earth's organisms are carbon-based life forms, we should pay
careful attention to the carbon cycle. Plants and animals actively participate
in this cycle by exchanging carbon dioxide out of and into the atmosphere.
Currently humans add 7 billion extra tons of carbon per year into the'
atmosphere by burning fossil fuels and forests.
••aV's??'','^
msi^ffess
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Dr. Art's Guide to Planet Earth
the carbon
cycle
The carbon cycle is harder to understand than the water cycle.
With 'the water cycle, we are talking about the same molecule
(H20). In going through the water cycle, these H20 molecules
change in their physical location and in their physical state
(gas, liquid and solid). In the carbon cycle, the carbon
atoms change not only in their physical condition but also
in their chemistry.
Carbon in the atmosphere is mostly present as the gas carbon
dioxide (CO2; one carbon combined with two oxygens). In living
and decaying matter, carbon is present as carbohydrates and
proteins where it bonds with oxygen, hydrogen and other elements
in a huge number of different chemicals. In the ocean, it is present
mostly as bicarbonate salts (bicarbonate is a combination of carbon,
oxygen and hydrogen that is also commonly found on supermarket
and kitchen shelves in the form of baking soda). With the carbon
cycle, we see the same carbon atoms changing their chemical
partners as well as their physical location and physical state (gas,
liquid and solid) as they flow from one reservoir to another.
-------
The carbon cycle illustration on the next page and chart below show five
major carbon reservoirs on Earth. Each of these reservoirs is an important
location where carbon exists on our planet. They are the Atmosphere,
Biomass, Ocean, Sedimentary Rocks and Fossil Fuels. The numbers next to
the arrows represent the rate (in billions of tons per year) at which carbon
enters and leaves each of those reservoirs. There is some uncertainty in the
exact value of these numbers but the relative amounts are correct.
Matter Cycles
Carbon Djtsdde.
(gas) ',
Not applicable ~ '
Greefl hoaste, gases
Per year; sbouf^yjb
eigatfltis Bowitr each
„ i fat*
direction
Burning forests
taleas-e.iabo.ut-i
gtgaton pfer year
Cafboriates "•
(softd) i
Mostly dis|olved
bicarborlate
the ocean is absorb
ing more*thaa ft *
releases.
Methane {gas),
Petroletflri
Abot*t 6 gigatons
natural background
rate through
(liquid),
Coal (sqlid) n
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Dr. Art's Guide to Planet Earth
It is easiest to understand the carbon cycle by exploring how each of the
different reservoirs interacts with' the atmosphere. We will examine how the
atmosphere interacts with life, rocks, oceans and fossil fuels. As we shall see
in the next chapter, atmospheric carbon dioxide plays an important role in
determining Earth's climate. This crucial role provides another reason to
focus on the atmosphere when we explore the carbon cycle. The atmosphere
contains 760 billion tons of carbon (as measured in the late 1990s), almost
all of it present as carbon dioxide. This CO2 currendy makes up 0.035% of
the atmosphere, a small percentage but essential for life as we know it.
The most well-known part of the carbon cycle involves life on the
continents (Land Biomass). When we think about life, we usually focus
CARBON CYCLE
-------
Matter Cycles
on animals. However, this part of the carbon cycle is really about plants and
trees and how they change carbon dioxide gas into living matter. Eventually
this living matter is used by plants, animals and decomposers to return the
carbon to the atmosphere, again in the form of carbon dioxide gas
(described in more detail in Chapter 4).
During an average seven year period, all the carbon in the atmosphere will
leave it and become part of land-based living organisms. Over the same time
period, an equivalent amount of carbon in these living or decaying
organisms will return to the atmosphere as carbon dioxide. The net result
from these interactions is that the amount of carbon in the atmosphere
remains constant even though carbon atoms constantly leave and enter the
atmosphere as they cycle through living organisms.
The oceans are a very significant reservoir in the carbon cycle,
containing about 20 times more carbon than land biomass and 50
times more carbon than the atmosphere. This ocean carbon is
present mostly as dissolved bicarbonate salt. The annual rate at
which atmospheric carbon enters and leaves the ocean is
similar to the rate of exchange with land biomass. In other
words, about every seven years all the carbon in the
atmosphere will leave it and become part of the ocean.
Similarly, about every seven years approximately the same
amount will leave the ocean and return to the atmosphere.
Rocks contain the vast majority of Earth's surface carbon,
more than 50,000 times as much as the atmosphere.
However, this huge store of carbon interacts with the
atmosphere at a much slower rate. In one direction, a
process called weathering removes carbon from the
atmosphere. In the other direction, hot springs,
volcanoes and other upheavals return carbon to the
atmosphere from Earth's interior. We met
this part of the carbon cycle before when we
explored our old friend the rock cycle.
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Dr. Art's Guide to Planet Earth
tnday'V rarbon
cycle
When we examined the water cycle, we noted how the
amount of water in each reservoir currently remains constant
The same amount of water evaporates from the ocean as
eventually returns to it in the form of rain or runoff from the
land. The same amount of water enters the atmosphere
through evaporation as leaves it through precipitation.
Cycles, such as the water.and carbon cycle, have changed during Earths
history. For example, during an ice age, a large amount of water leaves the
ocean and remains on land in the form of glaciers. As a result, the oceans
dramatically decrease in size. Islands may become part of the mainland and
land bridges may connect previously separated continents.
Todays carbon cycle is changing, but this time as the result of human
actions. The carbon cycle illustration on the previous pages shows that
humans are adding extra carbon to the atmosphere by burning forests and
fossil fuels.
Math:
K =
.
-------
Matter Cycles
The burning of fossil fuels (oil, coal and natural gas) accounts for the
greatest amount of carbon that humans are adding to the atmosphere.
Approximately 6 billion tons of carbon in the form of carbon dioxide enters
the atmosphere due .to the burning of fossil fuels for transportation, heating,
cooking, electricity and manufacturing. The carbon in fossil fuels comes
from living organisms that were buried millions of years ago. This fossil fuel
carbon had been stored deep underground in oil, coal and gas deposits, and
had therefore been locked out of the current atmospheric carbon cycle.
The global carbon cycle is currently not in balance. By burning
forests (1 billion tons) and fossil fuels (6 billion tons), humans
add more than 7 billion tons of carbon per year to the
atmosphere. What happens to all that carbon? Currently about
3 billion tons remain in the atmosphere with the result that the
concentration of carbon in the atmosphere has increased 25%
in the last century.
What happens to the rest? Since Earth is essentially a closed
system for matter, the extra carbon added to the atmosphere
has to end up somewhere. As you can imagine, it is difficult
to measure all the carbon in the ocean, trees or rocks. While
nobody can prove the location of this Missing Carbon,
scientists have some evidence that the oceans are absorbing
about half of this extra carbon and that growing forests may be
absorbing the other half.
At current rates of burning fossil fuels, the carbon in the atmosphere may
double in amount sometime around the year 2050. If the ocean and
growing forests do not continue to absorb more than half of the extra
carbon, this amount could increase even faster. The next chapter gives us a
very strong reason for caring whether and how fast atmospheric carbon
increases in amount.
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Dr. Art's Guide to Planet Earth
lore Chapter 2 on the web
1 ^,--.if.!'.i...;,?,.,: '..'>. "•*'*/!. iJ/^-i" ^'f^'iV*.-^'..*'^
' ^^ .V-*rU'^ jr»Wi*»'«rtr_ '*!
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Dr. Art's Guide to Planet Earth
part of a
larger system
Back in Chapter i, we introduced systems thinking as a way to
understand any system, especially a complicated one like
planet Earth. We said that three systems questions often help
us analyze the system that we are exploring. When we looked
at Earth's matter, we mostly used the first systems question:
"What are the parts of the system ?"
We examined Earth's solid, liquid and gas parts and discovered that they all
participated in cycles. We concluded that matter on planet Earth cycles, that
Earth is essentially a closed system for matter.
What if we asked the same system question about Earths energy? Looking
for Earth's energy "parts," we might run around measuring the wind, hot
springs, volcanoes, waterfalls and humans making fires. Then if we take a
break and relax on the beach, we would realize that we had ignored Earths
most important source of energy.
It's way out there. It's not one of Earth's parts. It provides our planet with
15,000 times more energy than all our societies consume. Of course, it's the
sun. To understand energy in the Earth system, we need to focus on a diEerent
systems question. Instead of looking at the parts of the Earth system, we need
to ask the third system question: how is Earth itself part of larger systems?
And the answer is as simple as the question — Earth is part of the solar
system. The sun provides virtually all the energy to keep our planet warm
and sustain life.
-------
Energy Flows
Since our solar system has many other planets, we also discover how
important it is to be close to the sun but not too close. "When the planets
first formed, the areas closer to the sun were too hot for anything but rocky
materials to solidify. So these inner planets (Mercury, Venus, Earth and
Mars) are mostly rock. In contrast, the outer planets (Saturn, Jupiter,
Uranus and Neptune) were cool enough to keep materials such as methane
and ammonia and they became very large, consisting mostly of atmospheres
containing these and other gases.
Some people have called the third planet from the sun the Goldilocks
planet. In the children's story of Goldilocks and the three bears, she found
the chair that was not too big or not too small and she ate the porridge that
was not too hot or not too cold. Earth is not too close to the sun, not too
far, not too hot, and not too cold. Earth is just right.
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Dr. Art's Guide to Planet Earth
e n "e r g y fro m
The
sun
Since energy never changes in amount, you might think that it
does not live up to its name, that it is pretty dull. Well, you
would be wrong. Energy is, well, energetic. While it does not
change in amount, it changes forms very readily.
Check out what happens to the solar energy that reaches Earth. About 30%
is immediately reflected back as light to outer space. Most of this light
bounces off the clouds and never reaches the surface. Some of it reaches the
16% heat 24% evaporates 5% winds
water
-------
Energy Flows
surface but bounces off snow and water, also leaving the Earth system in the
form of light. This reflected light makes Earth visible from space.
The remaining 70% of the sunlight that reaches Earth is absorbed. As
shown in the illustration, this absorption occurs in a number of ways. Most
of it is absorbed by solid materials and water and is immediately converted
to heat. We all experience this phenomenon when sunlight warms our
bodies. What we don't usually consciously experience is that this heat energy
radiates from our bodies. Any material that is heated by the sun will then
radiate heat outwards. Sometimes we see this heat as in the shimmering
waves of air above a hot pavement. Eventually that heat radiates duough
the atmosphere and leaves planet Earth by flowing to outer space.
A large amount of the solar energy evaporates water, thereby powering the
water cycle. Water absorbs this energy as it changes from die liquid state to
the gas state. Water vapor then leaves the oceans and enters the atmosphere.
However, when this water vapor condenses back to the liquid state (rain),
the same amount of energy is released in this condensation process as the
amount that was absorbed in the evaporation. This energy is now released as
heat that escapes to the atmosphere and eventually to outer space. So even
the incoming sunlight that powers the water cycle also eventually leaves
Earth in the form of heat.
The same fate awaits the solar inflow that is initially converted to the
moving energy of wind, waves and currents. The same fate awaits the tiny
but crucial amount (0.08%) that plants capture and convert to chemical
energy. The wind rubs against a cliff and some of its energy changes to heat.
A cow eats grass and converts the plant chemical energy to body heat which
radiates to outer space.
No matter how the energy is absorbed or changes its form, it never increases
or decreases in amount. That is one key characteristic of energy - it is never
created or destroyed. Another key characteristic is that energy changes form,
eventually changing to heat energy. All the solar energy that is absorbed on
Earth in one form or another eventually changes to heat energy that radiates
to outer space.
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Dr. Art's Guide to Planet Earth
t
h e
g r f
€$•••"• *
^ e
n
h o
use i
el
/ /7ai/e used #?e word "radiate" as if everyone knows what it
means. In the last section, you might even have become
annoyed with me repeating that "heat energy radiates to
outer space." Whoops, I just said it again. What do we mean
by that phrase?
You may also have noticed that I have avoided using scary
sounding scientific words in this book. Well, don't freak out, but to
explain solar energy and heat radiating, I need to use one — the
electromagnetic spectrum. Many very familiar forms of energy are
electromagnetic in nature. Examples include green light, red light,
microwaves, radio waves, ultraviolet light and X-rays.
We call them electromagnetic because, guess what, they have
electrical and magnetic properties. More importantly, they all travel
at the speed of light (in other words, as fast as anything can go), do
not lose energy as they travel (even over huge distances, such as
from the sun to Earth) and travel like waves.
Some of these forms of energy even have wave or ray right in
their name. All of them travel as waves and the feature that
makes them different from each other is their wavelength. Each
of these different forms of electromagnetic energy possesses its own
characteristic wavelength.
-------
Energy Flows
The wavelength is what makes green light different from a radio wave and
different from an x-ray. The wavelength of x-rays is about a thousand tunes
shorter than green light, while the wavelength of radio waves is about a
thousand times longer than green light. This spectrum (meaning a broad
range going from one end to the other) includes electromagnetic waves that
differ by more than a billion times in the size of their wavelengths.
"Which brings us to our sun. The sun is not boring. It doesn't give off just
one wavelength. It radiates energy across a fairly broad range of wavelengths.
You know this because you have seen rainbows, natural examples where
some of the sun's light separates into its different wavelengths. The longer
waves (which we see as red) appear at the top, and the shorter waves (blue)
at the bottom.
The sun radiates about half of its energy in the visible part of the
electromagnetic spectrum. We have evolved so we can see half of the sun's
radiant energy ranging from short wavelengths that we see as violet to
wavelengths about twice as long that we see as red. The sun emits 40% of its
energy in the infrared (IR) region (longer than red wavelengths, which some
animals such as rattlesnakes can see). It also emits about 10% of its radiation
as ultraviolet (UV) rays (shorter than violet, which some animals such as
bees can see).
A radio wave can have a wavelength a billion times longer than an X-ray.
Radar &
'Microwaves
Infrared
UV
X-Rays
Visible
light
Gamma
rays
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Dr. Art's Guide to Planet Earth
earth's
energy budget
We can think about Earth's energy in terms of a budget Just
like a family budget or a government budget, in any particular
time period, a certain amount comes in and a certain amount
goes out A family or a company or a government can borrow
money so they can send out more than they take in. Earth is
different Earth has a balanced energy budget
The amount of energy that flows out as heat from Earth's surface and
atmosphere to outer space is exactly equal to the amount of energy that
reaches the surface and atmosphere. As we have seen, solar radiation
accounts for the vast majority of that energy. A much smaller, but very
important, amount comes from the interior. Of course, at any given
moment more energy could be flowing in than is flowing out. But over the
course of a year or longer, this balances and the amount of energy flowing
out equals the amount of energy flowing in.
Earths "matter budget" would look very different. Essentially nothing comes
in and nothing goes out. The same stuff keeps getting used over and over.
In comparing matter and energy, we say that Earth is a closed system for
matter and an open system for energy.
The greenhouse effect adds an important feature to Earth's energy budget.
Certain gases in the atmosphere (most importantly, water vapor and carbon
dioxide) slow down the rate at which heat escapes from the Earth system. In
effect, these gases make the heat stay longer within the Earth system.
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Energy Flows
People often mistakenly think that the greenhouse effect is a bad thing, that
it is something that humans cause. Earths greenhouse effect has helped
make temperatures on the planet comfortable for life for billions of years. It
started long before anything resembling humans appeared on the scene.
However, you can always have too much of a good thing. As we learned
with the carbon cycle, we are currently causing the amount of carbon
dioxide in the atmosphere to increase. By adding greenhouse gases to the
atmosphere, we are changing Earths energy budget. We are making the heat
energy stay in the Earth system even longer than it would have. This is the
issue of global climate change that we will investigate in Chapter 5-
The main reason we care about Earth's energy budget and the planets
climate is that we and many other creatures live here. The next chapter
explores the system of life on planet Earth, including us.
The amount of energy
in equals the amount of
energy out. The greenhouse
effect and Earth's temperature
seem to be Increasing.
Year
1880
1999
Energy
in
1 00 units
1 00 units
Energy
out
1 00 units
1 00 units
Greenhouse
effect
32.5°C7?
33'C??
1
Average
Earth
temperature
about 14.5°C
abouflS'CJ
few m
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Dr. Art's Guide to Planet Earth
Exolore Chapter 3 on the web.
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Dr. Art's Guide to Planet Earth
1 i v
anet
Back in the 19605, NASA hired British scientist James
Lovelock to design space flight instruments to test whether
Mars has life. NASA chose Lovelock because he had already
invented sensitive instruments that could detect tiny amounts
of chemicals in our atmosphere. Lovelock thought about the
problem and told NASA that he already knew the answer.
Basically, he compared what we already knew about the
atmospheres of different planets such as Earth, Mars and Venus.
In the other planets except Earth, the atmosphere is exactly what
you would predict from the lifeless laws of chemistry and physics.
Earths atmosphere stands out like a green thumb.
Our atmosphere has way too much oxygen. That oxygen should
combine with iron and other chemicals in the Earths surface and
disappear from the atmosphere. In addition, our atmosphere has
traces of methane, another chemical that readily reacts with oxygen
(methane combines with oxygen to form carbon dioxide and
water). The only way our atmosphere could have so much oxygen
and also have significant amounts of methane is if something
beyond lifeless chemistry and physics were making both oxygen
and methane.That something is the network of life on this planet.
Looking at the substances in Mars' atmosphere, Lovelock saw no evidence
for life. Organisms living on the surface of a planet will use that planets
60
-------
life Webs
atmosphere as a source of the chemicals that it needs and as a place
to release chemicals that it produces. The boring chemistry of Mars'
atmosphere told Lovelock that Mars is essentially lifeless today.
As far as we know, Earth is unique in the solar system in being a planet of
life. Living creatures have dwelled here for almost four billion years. Life
has integrated itself so deeply within the operating system of our planet
that Earth without life simply would not be Earth.
When we investigated Earths matter, we asked the first systems question:
"What are the parts of the system?" In looking at Earths energy, we focused
on the third systems question: "How is the system itself part of larger
systems?" In exploring the system of life on Earth, we are going to focus on
the second system question: "How does the system function as a whole?"
What is this web of life and how does it work?
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Dr. Art's Guide to Planet Earth
watching e a
rfhbreathe
Earth's atmosphere did not always have this unusual
chemistry. For its first three billion years, it scarcely had any
oxygen. Where did the oxygen come from?
During the first three billion years, bacteria were the only organisms that
inhabited the planet. Fairly early in their history, they had already invented a
way to capture energy from sunlight and package that energy in chemical
form as sugars. As far as living creatures are concerned, this is probably the
single most important chemical reaction. We call it photosynthesis, meaning
"putting together with light."
In photosynthesis, carbon dioxide combines with water
to form sugar and oxygen. The oxygen comes from
splitting water (H2O) and is a by-product of the
reaction. Organisms that perform photosynthesis,
ranging from single celled bacteria to giant redwood
trees, capture the energy from sunlight, package it in
chemical form as sugars and release oxygen into the
atmosphere. They take carbon dioxide from the
atmosphere and pump oxygen into it.
So, doesn't that mean all the carbon dioxide should
disappear from the atmosphere and the oxygen should
keep increasing? No way. Animals and decomposers
help get the carbon from the plant material back into
the atmosphere. To get energy, organisms (plants,
bacteria, animals and fungi) internally burn sugars
-------
Life Webs
back into carbon dioxide gas. This reaction, the opposite of photosynthesis,
is called respiration. Organisms release the stored chemical energy by
combining sugars with oxygen to form carbon dioxide and water.
Although we did not use the words, we have already encountered
photosynthesis and respiration. One part of the carbon cycle illustration
from Chapter 2, reproduced here, shows two arrows connecting Land
Biomass with the Atmosphere. The arrow pointing downwards in the
drawing on page 62 represents photosynthesis — plants and trees taking
more than 100 billion tons of carbon out of the atmosphere each year and
converting it into sugars. The solid arrow pointing upwards represents
respiration — these plants, decomposers and animals internally burning that
sugar carbon and converting it back into carbon dioxide.
Water Carbon dioxide
Sugar
Oxygen
Respiration
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Dr. Art's Guide to Planet Earth
Of course you remember the other parts of the carbon cycle illustration,
especially how we are adding carbon to the atmosphere by burning fossil
fuels and forests. Back in the 1950s, scientists and government officials
realized that we needed to accurately measure the amount of CO2 in the
atmosphere to discover if it was changing. The most famous measuring
station, established on the highest mountain of Hawaii's Big Island, has
recorded data since 1958.
2000
First, notice that the amount of CO2 in the atmosphere has increased from
316 ppm (parts per million) in 1959 to 364 ppm in 1997. Even way back
in the 1950s, we had already been destroying forests and burning significant
amounts of coal and oil for more than a hundred years. To have a better
idea of human impacts, we would like to know the CO2 level before the
industrial revolution.
Scientists can actually measure CO2 levels in Earths atmosphere hundreds
and thousands of years ago. No, they don't physically travel back in time.
They analyze air bubbles trapped in ice below Earths surface. The deeper
below the surface, the further back in time they can measure. Using this
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Life Webs
technique, we have data showing that the atmospheric concentration of CO2
was about. 280 ppm in the year 1750 and had stayed fairly constant for the
previous 10,000 years. The 1997 concentration of 365 ppm provides strong
evidence that human activities have already caused more than a 25%
increase in atmospheric CO2.
What causes the squiggles, the repeating up and down lines, in the graph?
Scientists chose the mountain in Hawaii in the middle of the Pacific Ocean
so the measurements would be isolated from any major local pollution.
They were puzzled by the squiggles, tested various hypotheses and finally
concluded that these lines provide a picture of Earth "breathing."
The Hawaii station measures air from the Northern Hemisphere. In the
summer of each year, plants strongly increase their rate of photosynthesis
absorbing CO2 from the atmosphere and converting it into sugars. As a
result, CO2 levels go down. "When winter comes, photosynthesis decreases
while respiration continues releasing CO2. As a result, CO2 levels increase
during the winter above the summer level. Each year, the CO2 level starts
going down in the spring, reaches a low in late summer or early fall, rises
with the beginning of cold weather and reaches a high point before the
following spring/summer begins again. The graph shows us Earth's web of
life breathing in CO2 and exhaling it over the course of a year.
Each of us is part of that web of life, converting plant sugars and starch
back into atmospheric CO2. On a sunny day, I like to walk in a park,
meadow or forest and become aware that I am breathing with the plant life
around me. I inhale the oxygen that plants are releasing at that very moment
through photosynthesis. I exhale the carbon dioxide that they inhale at that
very moment through their leaves and use in photosynthesis.
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Dr. Art's Guide to Planet Earth
who is
i n . § a o
the webr
Earth has four kinds of stuff: solid, liquid, gas and living. In
comparison with Earth's living matter, there is four thousand
times more gas, one million times more liquid and four billion
times more solid Earth material. Yet, despite its small amount,
life plays very important roles on our planet
With respect to mass, almost all of Earths living stuff is in the form
of plant matter. All animal life adds up to only 1% of Earths
biomass. Trees and decaying plant matter account for almost all the
mass of Earth's living stuff.
The closer you get to the equator, the more trees there are. In
addition to having a warmer climate, there is a lot more land near
the equator than near the poles. As a result, tropical forests account
for about 40% of Earths total biomass. This is one reason why many
people are concerned about the high rate at which tropical forests are
being destroyed. If we burned all of Earths trees, that would double
the amount of carbon in the atmosphere.
Another important way to understand Earth's life is in term of the
kinds of organisms that exist rather than their mass. The word
"biodiversity" refers ito the number and kinds of different organisms.
We know very litde about Earths biodiversity. We have a more
accurate scientific estimate of the number of atoms in the universe than we do
of the number of different species on our planet.
66
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Life Webs
Scientists have currently named and catalogued about
1,500,000 different species of organisms. The estimates of the total
number range from 5 million to 30 million or even more. Of
die 1.5 million that have been described, all that we know
about the vast majority of these is what they look like and
where a few specimens were obtained.
Where is this biodiversity located? Here, too, the tropical forests play a
prominent role. Biologist E. O. Wilson once found as much diversity of ants
on one tree in Peru as exists in all the British Isles. A naturalist in 1875
described 700 species of butterflies within an hour walk of an Amazon river
town while all of Europe has only 321 different butterfly species. An area in
Indonesia totaling approximately 25 acres contained as many different tree
species as are native to all of Norm America. This wealth of biodiversity may
disappear hi smoke before we even know what we have lost forever.
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Dr. Art's Guide to Planet Earth
.ecosystem, and
Having discussed how much living matter there is and how
many different kinds there may be, we are still missing a
very important part of understanding life on Earth. How is
it organized?
The millions of species occupy specific places. The scientific term
ecosystem refers to the organisms that live in a particular place,
their relationships with each other and their interactions with the
physical and chemical parts of their environment. You may have
experienced different ecosystems such as a lake, meadow, creek,
forest, coastal tide-pool, coral reef or desert.
Ecosystems, like other systems, can be described or investigated at
many different levels. There are ecosystems within ecosystems
within ecosystems. A meadow ecosystem includes plants, insects,
gophers, snakes, deer, fungi and bacteria. The forest in which the
meadow is located is another ecosystem. An even larger ecosystem
would be a mountain containing the forest, meadow and perhaps a
lake. Earths web of life is the sum total of all Earth's ecosystems.
All the different ecosystems have a similar pattern of organization. They all
require a source of energy and a group of organisms that can capture that
energy and store it in chemical form. For the vast majority of ecosystems, the
sun provides the energy. Plant life, ranging from microscopic algae to towering
redwood trees, capture the energy in sunlight and store it as chemical energy
in sugar molecules.
68
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Life Webs
The organisms in an ecosystem that capture the energy are called producers
(labeled P in the illustration below). All the other organisms in the
ecosystem depend either direcdy or indirecdy on the producers for their food.
Animals are consumers, either eating plants (H, herbivores) or other animals
(C, carnivores). Another group of consuming organisms breaks down dead
plants and animals (D, decomposers).
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Dr. Art's Guide to Planet Earth
In any ecosystem, the producers, consumers and decomposers establish, a
network of feeding relationships called a food web. The same material keeps
getting used over and over again as one organism eats another and they all
decompose. Recycling is the ecosystem way of life.
Analyzing the energy flow through the ecosystem provides another
perspective on its organization. The organisms that have the highest total
energy flowing through them are the producers. All the biological energy
that flows through the ecosystem's organisms must first be captured
by these producers. In the course of living and reproducing,
some of that energy escapes as heat to the atmosphere. The
herbivores (cows, sheep, squirrels, etc.) that eat the
producers spend a lot of energy in maintaining their body
temperature, mating, eating and protecting themselves.
This energy eventually escapes to the atmosphere as
heat. Therefore there is less biological energy
available to support the carnivores (snakes, owls,
mountain lions, people) that eat the herbivores.
One result is that a typical terrestrial
ecosystem will have five to ten times as
much biomass in plant life than it will in
herbivores. It will also support five to ten
times as much biomass in herbivores as
it will in carnivores. This feature is
often portrayed as a pyramid
showing the producers as the
broad ecosystem base with a
narrower middle representing the
herbivores and a very narrow top
representing the carnivores.
70
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Think about the forest/meadow ecosystem shown on the
previous pages. Imagine that a new disease kills all the mice.
How might that affect the rabbit population?
The rabbits might increase since there may be more plant food
for them to eat. On the other hand, the owls and foxes might
eat more rabbits to replace the missing mice. This could cause a
decrease in the rabbit population.
This type of question often occurs when we study a system.
What happens when one of the parts changes? How do the
parts connect with and influence each other?
In general, the parts of a system connect with and
influence each other in two different ways. We call these
balancing feedback loops and reinforcing feedback loops.
A balancing feedback loop — surprise! — tends to keep things in
balance. Predators and prey exist in a balancing feedback loop. If a mouse
population increases, the hawks tend to increase since they have more mice
to eat. The increase in hawks then reduces the mouse population, serving to
balance the initial increase in mice.
Balancing feedback loops are very common. A thermostat is an example of a
balancing feedback loop. A room gets too cold, triggering the thermostat to
turn on the heater. When the room reaches the set temperature, the
thermostat turns the heater off. The room temperature stays in balance,
moving just a few degrees above and below the set temperature.
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Dr. Art's Guide to Planet Earth
Balancing Feedback Loops
Time
With a reinforcing feedback loop, a change in one direction causes more
change in the same direction. The high pitch squeal of a microphone is one
example of reinforcing feedback*. As another example, think about ten
rabbits being brought to a new continent where they have abundant food
and no natural predators. Each rabbit on average causes ten new babies so
the population quickly becomes 110. Each of these results in ten new
rabbits, a population of 110 + 1,100 = 1,210. This reinforcing feedback
loop (more rabbits causes more babies causes more rabbits causes more
babies) quickly results in a population explosion with millions of rabbits
reproducing like rabbits all over Australia.
Complicated systems such as ecosystems or the planet's web of life have
many parts that all direcdy or indirecdy connect with each other. A change
in one part will cause changes in other parts. Some of the changes get
balanced while others are reinforced. All these influences feed into each
other causing the whole system to change, often in unexpected ways.
You have probably experienced situations where simple actions cause
unexpected results.
* The microphone picks up some electronic noise, feeds it into the amplifier which makes the sound louder
and then broadcasts it via the speakers. The microphone picks up the louder noise, feeds it back into the
amplifier and this loop repeats making the sound louder and louder.
-------
Life Webs
Reinforcing Feedback Loops
Time
"Parachuting Cats Into Borneo" is a famous example. The World Health
Organization (WHO) sprayed the insecticide DDT in Borneo in the 1950s
in order to fight malaria, a disease spread by mosquitoes. The people lived in
homes with thatched roofs. Suddenly, their roofs collapsed.
In addition to killing mosquitoes, the DDT had killed parasitic wasps
that preyed on caterpillars that ate the roof materials. Without the
wasps, the caterpillars multiplied out of control and destroyed the
roofs. The local gecko lizards also died from eating DDT-poisoned
insects. The dying geckos were caught and eaten by house cats that
then died from the DDT. The death of the cats caused an increase in
rats which threatened to cause an outbreak of bubonic plague (a
terrible disease which is spread by rats). WHO then parachuted cats
into Borneo to try to control the rat population. They clearly did not
have this in mind when they began spraying DDT.
We keep learning this lesson about the web of life. All the parts are
connected via feedback loops. When we change the web of life, it is
hard to predict the consequences.
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Dr. Art's Guide to Planet Earth
s h r e d d i n g
The web
From our earliest beginnings, humans have affected the web
of life. Since everything is connected, we could say the same
thing about any organism. The difference is that we now have
a large human population and powerful technologies that
have far-reaching effects. Scientists estimate that we currently
take about one-third of the photosynthesis energy captured
and stored by Earth's land plants.
We are harming ecosystems locally and globally in at least six
different ways (see next page). As a result of all these actions, we
are beginning to shred the existing web of life. Should we care?
Can we do anything about it? In the next chapter, we will analyze
three global environmental issues, beginning with our effects on
Earth's biodiversity. The three Earth Systems principles (Matter
Cycles, Energy Flows, Life Webs) will help us understand these
global environmental issues as well as the local environmental
issues that we will explore in the final chapter.
74
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Life Webs
Isolating patches of natural habitat
HABMT DJESTHUCHON
Physically destroying natural habitat
POLLUTION
Adding chemicals to natural habitat
HARVESTING
Logging, fishing and hunting at faster rates
than nature can replace
EXOTIC SPECIES
Introducing plants and animals into new
ecosystems where they grow out of control
CLIMATE CHANGE
Increasing the amount of greenhouse gases in
the atmosphere resulting in changes to
Earth's climate
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Dr. Art's Guide to Planet Earth
Explore Chapter 4 on the web
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Dr. Art's Guide to Planet Earth
save the
planet?
You probably have seen the phrase, "Save the Planet."
My advice? Don't worry about saving planet Earth.
Our planet has lasted more than four billion years and
survived far greater calamities than anything we can do. We
cannot destroy planet Earth, Fortunately, we cannot even
destroy life on our planet.
About 65 million years ago, a large asteroid or comet probably crashed into
Earth. The evidence indicates that the force of the impact was equal to
exploding 7,000 times the amount of all the world's nuclear weapons. Even
that extreme catastrophe did not destroy all of Earth's life. It
probably caused the extinction of the dinosaurs and 75% of all
species living at that time.
Does that mean we don't have to worry how our actions can affect
the environment? I don't think so. Even though we cannot destroy
life on Earth,, we can cause changes that would be very harmful to
many of Earths current inhabitants, including ourselves.
-------
Think Globally
I would bet that on any day you could find something in the newspaper, TV
or radio that talks about one or more environmental issues. In general, there
are two different types of environmental issues — local and global. The
local issues concern the area close to where we live and the things in our
environment that affect us every day (food, air, water, garbage). In contrast,
the global environmental issues can change conditions throughout
the planet.
This chapter explores three issues that can change conditions on a planetary
scale. These global environmental issues are:
EXTINCTION
high rates of species
extinction and damage
to ecosystems
OZONE
destruction of the ozone in
the upper atmosphere that
protects organisms from the
sun's ultraviolet (UV) radiation
CLIMATE:
increase in greenhouse gases
in the atmosphere resulting in
climate changes throughout
the planet
Even without human influences, Earth goes through major changes over
time. As we explore these three global environmental issues, we will examine
how Earth has changed in the past. How fast did those changes occur?
How long does it take for Earth to recover from a major, global catastrophe?
How do changes that humans may be causing today compare with
previous changes?
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Dr. Art's Guide to Planet Earth
extinction
Life on Earth began
-------
Think Globally
01
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Biodiversity vs. Time
65 million years ago
the end of the dinosaurs
240 million years ago
95% of marine species extinct
500
400
300 200
Millions of Years Ago
100
Today
Note that biodiversity has suffered some major setbacks in its long history;
During the past 5.00 million years, there have been five major disruptions
that we call mass extinctions. The most extreme occurred, about 240 million
years ago when about 95% of the then-living marine species disappeared.
The most famous mass extinction occurred about 65 million years ago,
marked the end of the dinosaurs, and was probably caused by
the meteorite collision described earlier.
After each mass extinction, Earths biodiversity eventually
recovered. However, the process takes time, lasting millions of
years. Further, it is not the old organisms somehow coming
back. Recovery involves new species evplving and replacing the
old ones. Extinction is forever.
Extinction occurs even in "normal" times. Biologists estimate
that this background level of extinction averages about 10 to
25 species per year. What about today? Many ecologists are
concerned that we are already in the midst of mass extinction,
this time caused, not by a meteorite from outer space, but by
Earth-born creatures that walk on two legs.
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Dr. Art's Guide to Planet Earth
Of course you remember "Shredding the Web," the last part of Chapter 4
(p. 74-75). Humans engage in six different .types of activities that harm the
existing web of life. These include destroying habitat, polluting, and
harvesting (hunting, fishing, logging) at faster rates than nature can replace.
In many ecosystems, we do all these things at the same time. When people
move into or economically develop a new area, they build roads that
fragment the habitat, cut down the forests, spill chemicals on the ground
and in the rivers, bring in domestic animals, and kill the local animals.
Now we are threatening to change the climate as well. A
plant or animal species that has already decreased in
numbers due to loss of habitat and exposure to pollutants
may not be able to survive a change in climate. If the new
climate makes its current habitat unsuitable, it may not
simply pack up and move to a new area whose new
climate could be satisfactory. First, highways, suburbs and
cities may block the way. Second, species depend on each
other. The climate in an area may be perfect, but an
organism will not be able to live there if diat area does
not have the plants and animals that it needs for food
and shelter.
What is happening to the web of life today? Many respected biologists
believe that we are already beginning to experience a mass extinction that is
as severe as the mass extinctions that occurred in the past. The normal
background extinction rate is about 10 to 25 species per year; the current
rate is probably at least several thousands of species per year and may be ten
times that high.
How can we continue our normal lives without even being aware of a mass
extinction? Well, most of us live in or near cities, far from the areas where
most of Earths biodiversity exists. We live far from the areas that are
currently experiencing major habitat destruction, the main cause of
extinction today. Tropical rain forests that are home to about hah7 of Earth's
biodiversity are being destroyed every day.
82
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Think Globally
Should we care about all these species disappearing? Most of them are
insects and even smaller organisms that none of us would ever see.
Many people want to prevent extinctions because they believe that it is
morally wrong to destroy ecosystems and cause other organisms to
disappear forever. Many people also believe that the natural world should
be protected simply because it is beautiful. Both of these arguments say that
we should protect ecosystems even if they do not have any practical,
economic importance.
Another kind of argument states that Earth's biodiversity has
tremendous economic and practical value, and that we are already
destroying irreplaceable wealth. About one quarter of the medical
drugs produced in the United States contain ingredients that were
first discovered in plants. Aspirin, the most commonly used
medical drug, is one example. The rosy periwinkle, a plant which
grows only in Madagascar, gave us a drug that cures almost all
cases of childhood leukemia, a disease that previously killed
almost all its victims.
Plants have developed an incredible variety of chemicals over
millions of years. When a new disease or insect attacks a plant
crop, scientists search the natural world for varieties that are
resistant to that disease or insect. They can then protect
important crops such as rice and wheat by breeding in the
resistance from the wild varieties. When a plant species become
extinct, we may have lost forever a cure for AIDS, cancer, or diseases that
attack our food crops.
The natural world also provides free services that we tend to take for
granted, including clean air, clean water and food. Organisms play
important roles in Earths cycles of matter such as the carbon, nitrogen and
sulfur cycles.
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Dr. Art's Guide to Planet Earth
How many species can disappear before todays web of live unravels?
The answer is - we do not know. We don't know the details of how most
ecosystems work. We don't know how ecosystems interact with each other.
We don't know how different ecosystems or combinations of ecosystems
support the larger global system. We don't know how many species
there are today, how many are going extinct right now, and what
will happen if we continue our present activities. We don't know.
There is one thing that we probably do know. Humans like to
protect cute, exciting, powerful and/or cuddly creatures. We want
to save the whales, cheetahs, and pandas. We also like to protect
ourselves. However, we and other carnivores sit at the top
of ecosystem pyramids. That makes us more vulnerable to
ecosystem changes.
Damage to top-
base remains
Damage to base...
top collapses
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Think Globally
The producers, who capture the sun's energy, and the decomposers, who
help recycle matter, play crucial roles in ecosystems. These very important
parts of Earths biodiversity are the plants (including plankton, microscopic
organisms diat support ocean ecosystems), and the ugly, the invisible, and
the smelly (including fungi, bacteria and insects). These are
creatures that we usually do not see on TV, refrigerator magnets,
the zoo, or newspaper articles.
Many scientists and government officials now try to protect
ecosystems rather than focusing on an individual species. When
a species is endangered, we can take that as a warning sign that
we need to protect the ecosystems to which it belongs. That way,
we can protect the producers, the smelly, the invisible, and the
ugly, and maybe ourselves in the long run as well.
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Dr. Art's Guide to Planet Earth
the ozone
ayer
The second global environmental issue involves the thin but
vital layer of ozone in the upper atmosphere. This ozone
protects Earth's organisms from the sun's ultraviolet (UV)
radiation. Chemicals that humans have produced are
destroying this ozone and causing an increase in the amount
of UV radiation that reaches the Earth's surface.
Ozone is a form of. oxygen. While the familiar form of oxygen contains two
oxygen atoms bonded together (Ch), ozone has three oxygen atoms connected
with each other (Oa). This change in chemical structure causes these two
different forms of oxygen to have different properties. We breathe the two-
atom form in order to live. The three-atom form is actually quite toxic to us.
Oxygen (02)
Ozone (OJ
86
-------
Think Globally
Watarat result of *
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Fortunately, most of Earth's ozone is in the upper atmosphere, 15 to 50
kilometers (about 9 to 30 miles) above our heads. Up there, it absorbs the
suns UV radiation and protects us. Actually, some ozone occurs in the lower
atmosphere that we breathe. This ozone is part of the city smog caused by
pollution, and it is a local environmental issue because it harms our lungs.
Some people call them good ozone and bad ozone.
We care about the good ozone because it protects life from the sun's UV
radiation. Even small increases in UV exposure can cause increases in skin
cancer and eye cataracts, and perhaps damage to the immune system. We
don't know how much different levels of UV radiation will damage Earth's
incredible variety of interlinked organisms and ecosystems. At the least, it
would be more stress on the web of life.
If we traveled back in time, we would discover that Earths atmosphere did not
always contain ozone. In fact, up until about 2 billion years ago, Earths
atmosphere had essentially no oxygen. Remember that for the first two billion
years of life, the only organisms were microbes living in the ocean who were
busy inventing swimming, behavior, sex, and .... photosynthesis.
Well, litde did they know it, but the oxygen that they kept making through
photosynthesis eventually built up to the point where it changed the
atmosphere and the history of life on Earth. As soon as there was oxygen in
the atmosphere, it reacted with incoming UV rays and formed ozone. This
ozone absorbs UV radiation and prevents it from reaching the lower
atmosphere and the Earth's surface. The stage was set for life to eventually
move out of the protective ocean and onto the land.
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Dr. Art's Guide to Planet Earth
Using the fast-forward button on our time machine, we return to the present
and discover a newspaper headline saying something about the ozone hole.
"Why would people make chemicals that destroy the protective ozone in our
upper atmosphere?
They were trying to do a good thing. In the early 1900s, chemists
were trying to create the ideal chemicals to be used in refrigerators.
These substances had to be stable so they did not break down right
away. They also needed to be chemically inert, meaning that they
would not interact with other substances. That way they would not
corrode the refrigerators or cause health problems for humans.
The chemists succeeded, resulting in a huge new industry for
refrigerators and air conditioners. Most people in the industrial
world now take it for granted that we can have safe, cold food as
well as comfortable indoor temperatures during the summer. The
chemicals that made it possible are small carbon-based molecules
that also contain chlorine and fluorine atoms. They are called
chlorofluorocarbons, CFCs for short.
Carbon
Chlorine
Fluorine
Meet a
chloroflurocarbon (CFC)
88
-------
Think Globally
Well, guess what happens to a chemical that is very stable and that does not
interact with other substances? Nothing. It keeps accumulating. It does not
participate in Earth's cycles of matter. As we find more uses for it and make
more of it, the more the chemical eventually finds its way into the atmosphere
and just hangs around.
It hangs around outside the cycles of matter . . . until it drifts miles above the
Earth and reaches the upper atmosphere, where ozone molecules and UV
radiation interact. There it finally meets something that can tear it apart —
high energy UV radiation. "When a UV ray breaks up a CFC molecule, it
releases chlorine. Unfortunately, chlorine atoms destroy ozone. Each of these
CFC chlorine atoms that is released in the upper atmosphere can destroy
100,000 ozone molecules.
Scientists and environmentalists had been
concerned about the ozone layer, but
businesses and governments generally opposed
making changes until there was more proof.
After the discovery of the ozone hole,
scientific research provided very strong
evidence that CFCs cause the hole. "With that
information, the world community organized
and took action.
Environmental ministers from 24 nations,
representing most of the industrialized world,
met in Montreal in 1987 and agreed to limit
the production of substances that damage the
ozone layer. A stronger agreement in 1990
provided bigger and quicker reductions in the
use of these chemicals. The graph shows how much these chemicals have
already increased in the atmosphere and the predictions of what will happen
in the future.
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1950
2100
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Dr. Art's Guide to Planet Earth
We know that damage to the ozone layer increases the amounts of UV light
that reaches the surface. Since the ozone levels naturally change over time due
to weather conditions, volcanic activity and other causes, we do not have
accurate information about how much extra UV radiation is happening right
now because of CFCs and other manufactured chemicals. We do know that
the protecting ozone layer has decreased over populated areas, resulting in
increased UV radiation at some times of the year. We currendy expect the
ozone layer to slowly recover and return to its pre-industrial level between the
years 2050 and 2100.
This ozone story tells us that very unpleasant surprises can happen
if we ignore Earths cycles of matter. We manufactured large amounts
of a new kind of chemical. Since they could not be naturally
recycled, they accumulated in the atmosphere. Eventually, they
harmed Earths ozone layer. We are beginning to realize diat
comparatively small amounts of man-made chemicals can
dramatically change important features of the Earth system.
Fortunately, we probably have caught this problem before it could
become a global disaster.
-------
Think Globally
The Ozone Hole Surprise
Scientists knew that we had to be concerned about the ozone layer in the
upper atmosphere. After all, it is pretty thin. If all the ozone up there were
concentrated and brought to ground level, it would form a shell around the
Earth that is only 0.3 cm wide. In reality, the ozone is spread very thinly in
the stratosphere from 15 to 50 kilometers above die ground.
So scientists were measuring ozone levels all around the globe. A British
group in the early 1980s measured that the ozone dramatically fell during
the Antarctic Spring mondis (Fall in the Northern Hemisphere). At first
they were very reluctant to publish their results. After all, they were using
old equipment. The Americans using sophisticated equipment on a NASA
satellite were reporting normal ozone levels. Finally, they published their
results in a major scientific journal.
Suddenly lots of people were talking about the "ozone hole." Actually, it is
not a hole. It is a very large area over die South Pole where die ozone
concentrations drop 60% or more during the Spring months. The area
affected is as large as die United States plus half of Canada.
How did the NASA scientists miss the
ozone hole? Their data showed the same
hole. Unfortunately, they had
programmed their computer to ignore
any data which was too far outside die
range that they had expected. One of
the important lessons to learn in science
(and in life) is to be prepared for
surprises, both pleasant and unpleasant.
Antarctic Ozone Readings
ile
1957
1977
198S
Year
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Dr. Art's Guide to Planet Earth
r I i m a t e
cfhange
We have already met the third global environmental issue:
climate change. Our time Earth systems principles help us
understand this issuei We are disturbing the cycles of matter
by putting greenhouse gases into the atmosphere. These
gases interfere with the planet's flows of energy. The resulting
climate change can damage the web of life.
Climate is different than weather. "When we talk about weather, we
care if it is raining, sunny, hot or cold in some particular place
today or next we ;k. With climate, we care about the pattern of
weather over a longer period of time and usually over a broader
area. Global climate refers to the pattern of temperatures and
precipitation for the planet as a whole.
The Major Co
d and Warm Periods During Earth's History
Simple
bacteria
Complex single-celled
organism
Today
1 cm = 200 million years
I = warm
! = cold
-------
Think Globally
In Earth's fiery beginnings, it was so hot that it
completely melted. Once it settled down about 4
billion years ago, Earth has never been so hot that
the oceans boiled or so cold that the oceans
completely froze. During those 4 billion years,
Earth has been mosdy warm with occasional cold
periods. Over the past 2,500,000,000 years Earth
has been warm 75% of the time and cold about
25% of the time.
When it is warm, Earth has litde or no
permanent ice covering its land. That may be a
surprise to most of us who are used to thinking
of Earth with permanent ice at both poles.
During its cold periods, Earth has lots of ice that
covers land throughout the year. Today about
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10% of Earth's land surface is covered with ice.
20,000 years ago, ice covered about 30% of
Earth's land surface.
Earth is actually considered to still be in a cold
period that has lasted about two and a half
million years. Right now, we are in what is called
an interglacial, a warm part of that cold period.
We came out of a deeper Ice Age only about
10,000 years ago.
The highest
skyscfaper
is;'about
500 meters.
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Dr. Art's Guide to Planet Earth
"What causes these changes in Earths climate? Three factors determine
whether Earth has a cold or warm climate:
• How much solar energy enters the Earth system;
• How solar energy circulates within the Earth system;
• How heat energy leaves the Earth system
Solar Energy Into the Earth System
The sun provides the vast majority of Earth's energy. Earths orbit around
the sun changes in a number of ways. For example, the tilt of Earths axis
changes from 21.5 degrees to 24.5 degrees in a 41,000 year cycle. A
different 100,000 year cycle involves a change from a nearly circular orbit to
a more elliptical one. During the past several million years, these changes
appear to cause a repeating pattern of long cold periods with briefer warm
periods (the interglacials) that last ten to twenty thousand years.
Earth's Orbit
100,000 years
94
41,000 years
21.5°
24.5°
Earth's Axis
21.5°
24.5°
21.5°
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Think Globally
How Solar Energy Circulates Within the Earth System
Tropical areas near the equator receive much more sunlight than the
polar regions. The result: places like Hawaii, Ecuador and Egypt are
much warmer than Iceland and Antarctica. Actually, based on the
amount of solar energy they receive, we would predict that the places
closer to the pole (especially in the Northern Hemisphere where most
of the land is) would be much colder than they are. However, the
atmosphere and the oceans carry heat from the tropics toward the
poles. Without this circulation, cities such as London, Paris, Moscow
and Berlin would be much colder than they are today.
How Heat Energy Leaves the Earth System
The greenhouse effect (see pages 50-53) plays the key role here. Heat
radiating from Earth's surface does not immediately leave the Earth
system. Greenhouse gases in the atmosphere absorb the heat rays and
send them back to Earth. As a result, the energy remains longer in the
Earth system and Earth is 33 degrees C (60 degrees F) warmer than it would
be without the greenhouse effect.
Water vapor and carbon dioxide are the two main natural greenhouse gases.
Scientists have analyzed air
Ocean Circulation
bubbles trapped in the
Antarctic ice sheet.
The data indicate that the level
of carbon dioxide in the
atmosphere is strongly
connected with Earth's climate.
Periods of higher amounts
of CO2 correspond with
warmer climates and times
with lower CO2 correspond
with colder climates.
300-
CC>2 vs Global Temperature
200,000
150,000 100,000
Years before today
50,000
Today
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Dr. Art's Guide to Planet Earth
i c e
age orhot house?
We would like to know the answer to what sounds like a
simple question. Can we expect the climate to remain the
same, become colder or become hotter?
Based on the pattern for the past 160,000 years, we would predict that
Earth will go deeper into an Ice Age within the next ten thousand years.
However, human activities are adding at least six different greenhouse gases
to the atmosphere. We might therefore predict that Earth will experience
global warming. In fact, the evidence seems to indicate that this global
warming has already begun. The last two decades of the twentieth century
were the warmest in recorded human history.
Computer models predict that global temperatures will increase 1 to 4
degrees C within the next 100 years. That may not sound like much, but
consider that the coldest and warmest periods in the past several million
years involved changes of just 5 to 10 degrees C. Further, we are making
our changes at an extremely rapid rate. The previous warming averaged
about 1 degree C per thousand years. We may be causing temperatures to
change 10 to 40 times faster.
We don't know how the Earth system will respond to these changes. Earths
climate results from a truly awesome combination of interlinked feedback
loops (see pages 72-73). Some examples include:
Temp.t
REINFORCING FEEDBACK
Mi
TGreenhouse
lethanet
effect
enhc
Greenhouse!
effect
Temi
Methane!
As the northern polar regions warms, frozen methane
(a greenhouse gas) could evaporate and cause even
more warming.
Temperature keeps getting higher.
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Think Globally
-Clouds
-Temp.T-
BAL.ANC1NE FEEDBACK
A warmer world will have more clouds. These could make the
climate colder by blocking sunlight.
Temperature stays balanced.
, Temp.t
CO2 in T fe
mosphere \
tGreenhouse.—.. \ Green
Temp.t
ousel
effect
REINFORCING FEEDBACK
As the ocean warms, it may absorb less C02, thereby
increasing the amount in the atmosphere.
Temperature keeps getting higher.
SURPRISE!!
Higher temperatures could cause changes that stop the
ocean currents that carry the heat from the Equator
toward the North Pole. Cooling of northern land areas could
trigger a severe Ice Age.
Warm temperature causes an Ice Age!!
The take-home message is that we are conducting an uncontrolled
experiment with Earths cycles of matter, flows of energy and web of life. A
warming climate could cause sea levels to rise; increases in severe weather
events (tornadoes, hurricanes, floods); massive changes to agriculture;
movement of diseases such as malaria into new areas; and added stress on
the web of life. The social and economic costs could be enormous. Should
we change? What choices do we have? Does the last chapter have
any answers?
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Dr. Art's Guide to Planet Earth
lore Chapter 5 on the web
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Dr. Art's Guide to Planet Earth
healthy alty water
How would you feel if you saw the following signs in your
neighborhood? "PUBLIC HEALTH WARNING. Don't drink the
water. Don't breathe the air. Don't eat the food."
Most of us get very concerned when we hear that our air, water, or
food could make us sick rather than keep us healthy. We may hear
warnings on the radio to stay indoors on certain days because the
local air has high smog levels. Jn 1997, the United States
Environmental Protection Agency reported that 107 million
Americans experienced unhealthy air, mainly ozone caused by
using fossil fuels.
How safe is our air, water and food? In many parts of the world,
people still get very sick and even die because their water has
organisms that cause diseases such as cholera. In comparison, those
of us who live in the developed world generally do not have
to worry that we will get very sick from germs or worms
contaminating our water, air or food. Our local environmental
health issues relate to chemicals that may be in our air, water, and food.
You would probably be surprised if you made a list of all the chemicals in
the products we use, the fuels we consume, and the food we eat. We make
and use thousands of different substances that either previously did not even
exist in nature or were present in local environments in very limited
amounts. These include simple elements such as lead in paints as well as
complicated substances whose names are so long that we only call them by
their initials.
too
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Remember "matter cycles," one of our three Earth systems principles?
Nothing simply disappears. "When we put chemicals in our air, water, and
land, we should not be surprised if they increase in amount. They may not
fit into the existing, natural cycles of matter. Each chemical will have its
own pattern of where it accumulates, how it breaks down, and how it
interacts with other substances and with organisms such as humans.
Concerns in the developed world about healthy air, water, and food
generally arise because we have not paid enough attention to the principle
that matter cycles.
lOi
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Dr. Art's Guide to Planet Earth
the three
R's
Healthy air, water and food is one local environmental issue.
A second local issue concerns the vast majority of substances
that we encounter that are not toxic. Even the safest things
that we use create a local environmental issue that most of us
deal with every day: garbage. After we have finished using
something, we have to figure out where to put it.
Both of these local environmental issues (environmental health and
garbage) result from not paying enough attention to the cycles of
matter. To maintain a healthy environment, we care about the
quality of the substances that we use. "We want to make sure that we
are not exposed to toxic chemicals as a result of how they are made,
used and thrown away. In the case of garbage, we care about the
quantity of stuff that we use, where it came from, and where it goes.
Try the following experiment. Carry a garbage bag with you for
an entire day. Instead of throwing anything away, put it in the
garbage bag. At the end of the day, weigh your garbage bag. Add 5
pounds for every gallon of gasoline that you burned during the day
(calculated by dividing the miles you traveled by the fuel efficiency
of miles per gallon per person). Now, multiply that weight by 40
to calculate how much solid waste you produced that day.
* Natural Capitalism by Paul Hawken, Amory Lovins and L. Hunter Lovins.
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The gasoline helps account for the waste produced in meeting all our energy
needs. But why multiply by 40? Because we do not see almost all the solid
waste that we produce. Industry created about 40 pounds of solid waste in
order to make each pound of stuff that we threw away. As one extreme
example, it takes about 20,000 pounds of stuff to make a five-pound
laptop computer.
Three Rs can drastically reduce these awesome amounts of garbage that
we produce.
REDUCE:
use less stuff. Examples include deciding you don't
really need another pair of new shoes, buying
products that use less packaging and that last
longer, and saving energy.
REUSE
use the same stuff over and over again. Examples
include canvas shopping bags, buying previously
worn clothes, and fixing something rather than
throwing it away.
RECYCLE
make new stuff from old stuff. Examples include
composting, aluminum cans, and recycled paper.
Consumers can reduce garbage by practicing the Three Rs and by
supporting businesses that pay more attention to Earth's cycles of matter.
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Dr. Art's Guide to Planet Earth
1O6
what
about
energy?
So far in this chapter,
does energy connect
we have discussed matter and life. How
with local environmental issues?
Obviously, energy plays a very important role in our daily lives. We use
energy when we go from place to place; heat, cool, and light our homes and
businesses; grow, distribute! preserve and cook our food; and clean ourselves
and our clothes. In: everyth ng that we do, we use a source of energy such as
gasoline for the car, natural
sunlight to heat the water.
gas for the stove, electricity for the refrigerator, or
Currently, most of that enejrgy comes from'fossil fuels. Coal, oil and natural
gas account for about 80%
and worldwide. Whenever
thereby increase the greenh
of the commercial energy consumed in the U.S.
we burn a fossil fuel, we release carbon dioxide and
ouse effect. Use of fossil fuels also causes pollution
from the combustion, mining, transporting and refining processes.
These pollution and greenhouse issues all take us back to the principle that
Matter Cycles. Whenever we use stuff to get energy, we have to pay attention
to where that stuff came frm and where it goes.
None of us wants to burn oil, coal or natural gas for its own sake. We want
services such as transportation, heat, light, entertainment, etc. Can we use
energy sources to get these
ind reduce our impacts on the cycles of matter?
Amory Lovins, a physicist j
The Rocky Mountain
we can save huge amounts
technologies in our cars,
£ nd energy consultant, answers with a definite yes.
Insti ute, led by Amory and Hunter Lovins, claims that
jf energy by using the latest energy efficiency
hqmes, businesses and industries. Their home/office
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Act Locally
The gasoline helps account for the waste produced in meeting all our energy
needs. But why multiply by 40? Because we do not see almost all the solid
waste that we produce. Industry created about 40 pounds of solid waste in
order to make each pound of stuff that we threw away. As one extreme
example, it takes about 20,000 pounds of stuff to make a five-pound
laptop computer.
Three R's can drastically reduce these awesome amounts of garbage that
we produce.
REDUCE
use less stuff. Examples include deciding you don't
really need another pair of new shoes, buying
products that use less packaging and that last
longer, and saving energy.
use the same stuff over and over again. Examples
include canvas shopping bags, buying previously
worn clothes, and fixing something rather than
throwing it away.
RECYCLE
make new stuff from old stuff. Examples include
composting, aluminum cans, and recycled paper.
Consumers can reduce garbage by practicing the Three Rs and by
supporting businesses that pay more attention to Earths cycles of matter.
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Dr. Art's Guide to Planet Earth
local
ecosystems
/ grew up in New York City. My environment was tall
apartment buildings standing side by side with no space in
between, and city streets with double-parked cars. As a child,
I thought my local park was a place where they had dumped
dirt on top of the concrete so grass, trees and squirrels could
live there.
Just 500 years ago, people's local environments looked very different.
With less than one-tenth the number of people and a much higher
percentage living on the land by hunting and farming, people
connected much more direcdy with the natural world. Their local
ecosystems resembled, or even were, what we call wilderness today.
We cannot change today's urban environments back into wilderness.
We have permanendy changed habitats; killed the local animals and
vegetation; brought in our favorite animals and plants; and polluted
the land, air and water. However, if we want, we can reduce the
amount of new damage that we cause, and we can even begin
to improve the biological health of our local environments.
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Act Locally
Chicago's UrbanWatch shows how an urban community can investigate
and help restore its local environment. Thousands of Chicago residents
participate under the leadership of the Field Museum of Natural History to
scientifically investigate natural areas in their local environments. Research
scientists at the Held Museum and the Illinois Department of Natural
Resources help decide which organisms people should observe, provide
information and skills, and analyze the data gathered by the participating
families, students and community groups. .; , . -;
People investigate city green spaces such as backyards, vacant lots, parks and
golf courses. And guess what? The scientists want them to look for those
"invisible," smelly and ugly organisms that we highlighted in the last chapter
as playing important roles in ecosystems. UrbanWatch participants use the
web (www.fmim.org/UrbanWatch) to learn about Chicago organisms and to
share the data they gather. The project aims to use this information to help
scientists, policy makers and local residents to protect and nurture their local
urban ecosystems.
Chicago's Urban Watch helps city dwellers identify
organisms in their local ecosystems.
What kind of
beetle am I?
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Dr. Art's Guide to Planet Earth
what about
energy?
So far in this chapter, we have discussed matter and life. How
does energy connect with local environmental issues?
Obviously, energy plays a very important role in our daily lives. We use
energy when we go from place to place; heat, cool, and light our homes and
businesses; grow, distribute, preserve and cook our food; and clean ourselves
and our clothes. In everything that we do, we use a source of energy such as
gasoline for the car, natural gas for the stove, electricity for the refrigerator, or
sunlight to heat the water.
Currently, most of that energy comes from fossil fuels. Coal, oil and natural
gas account for about 80% of the commercial energy consumed in the U.S.
and worldwide. Whenever we burn a fossil fuel, we release carbon dioxide and
thereby increase the greenhouse effect. Use of fossil fuels also causes pollution
from the combustion, mining, transporting and refining processes.
These pollution and greenhouse issues all take us back to the principle that
Matter Cycles. Whenever we use stuff to get energy, we have to pay attention
to where that stuff came from and where it goes.
None of us wants to burn oil, coal or natural gas for its own sake. We want
services such as transportation, heat, light, entertainment, etc. Can we use
energy sources to get these and reduce our impacts on the cycles of matter?
Amory Lovins, a physicist and energy consultant, answers with a definite yes.
The Rocky Mountain Institute, led by Amory and Hunter Lovins, claims diat
we can save huge amounts of energy by using the latest energy efficiency
technologies in our cars, homes, businesses and industries. Their home/office
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in Snowmass, Colorado (where winter temperatures can reach
minus 40 degrees) is so well designed that the sun provides 99%
of its space and water heating. Located at over 7,000 feet
elevation, the Lovins harvest bananas in December that grow
inside their home/office! i
Their approach is to radically reduce the amount of energy that
is needed for services such as heating or cooling. For example,
they use superinsulating windows that provide lots of natural
light. Unlike the usual windows, these act as a barrier preventing
energy from flowing into or out of the house. In contrast, a
typical home or office needs to consume fuel to make up for the
heat lost through the windows in winter and for the heat
brought in through the windows during the summer.
People and groups who push for strongly improving energy
efficiency also often argue that society can and should meet its
remaining energy needs using renewable energy sources such as
solar, wind and hydropower. When we studied energy in Chapter
3, we discovered that the sun provides 15,000 times as much
energy as human societies consume today. These renewable
energy sources tend to cause less pollution than fossil fuels, and
they generally do not increase the greenhouse effect. On the
down side, renewable energy sources tend to be less convenient.
Other people and groups argue that we do not need to be as
concerned with the greenhouse effect, that fossil fuels can be
used more cleanly, and that switching to renewable sources will
cost too much and hurt the economy. Almost everyone agrees
that improving efficiency makes sense, but there is disagreement
over how much energy can be saved this way. I agree with the
Rocky Mountain Institute that a combination of energy
efficiency and renewable energy sources can enable people in
both the developed and developing nations to have a high quality
of life with fewer environmental impacts than today.
LigHt etiteirs^ ^ ;;-
window
Heat escapes
from house
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Dr. Art's Guide to Planet.Earth
what can
How MUCH Do You GET
EACH DAY?
Imagine that today is your lucky day. A very rich person says
she will give you a million dollars a day for thirty days OR a
quarter today, 50 cents tomorrow, a dollar on Day 3, and will
continue doubling the amount for 30 days. Which would
you choose?
In the first choice you would get 30 million dollars total. In the second
choice, even though you start at just 25 cents on Day 1, you would get 134
million dollars on the 30th day! Do the math yourself to see how this works.
We use the term "exponential growth" for this kind of explosive increase in
amount. Humans today can change the way our planet operates because
exponential growth has vastly increased both our population and the
amount of materials that we use. Modern humans originated about 200,000
years ago. It took all our pre-history until the year 1800 before the
population reached 1 billion. Then it took 130 years for that number to
increase by another billion. Nowadays Earth's human population increases
by 1 billion people about every 12 years.
i billion (1800)
2 billion (1930)
§R(BBQ^.£^f^S^8^^i^
200,000 years
130 years
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Most of that population lives in developing nations, places such as China,
South America, India, Africa and Indonesia. About 15% of the world
population lives in the developed world in places like the U.S.A., Western
Europe, and Japan. Even though the7 are a minority, the citizens of these
countries tend to have a greater impact on the environment because of their
high consumption levels and technology-based societies, A typical American
uses 106 times as much commercial energy as a citizen of Bangladesh.
If everybody lived the way Americans do, the environmental
impacts would be much larger than they are today. Many of us
who live in the developed world understand this situation and
care about the environment. Nine out often Americans agree
that protecting the environment will require most of us to
make major changes in the way we live.
But what can we do? We hear about recycling, choosing paper
or plastic at the supermarket, turning off lights, carpooling,
and selecting reusable or disposable diapers. Which of the
many things that we could do would actually make the
biggest difference?
A book from the Union of Concerned Scientists shows
one way that we can decide. Called The Consumer's Guide to
Effective Environmental Choices, this book analyzes American
society and explains how the different things that we do in our daily lives
affect the environment. I include their conclusions in Dr. Art's Guide to
Planet Earth because the authors, Dr. Michael Brower and Dr. Warren Leon,
use science-based, systems thinking. They use the systems approach that we
described back in Chapter 1. Brower and Leon analyze the different parts of
our consumption system, study how these parts connect with each other,
and include how they are part of the larger environment.
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Dr. Art's Guide to Planet Earth
The bar graph summarizes their conclusions. First, they decided to focus
on four major kinds of environmental impacts. Two of these are global
environmental issues that we discussed in the previous chapter (global
warming = global climate change; habitat alteration = extinction/loss of
biodiversity). The other two environmental impacts are major local
environmental issues (air pollution and water pollution). They did not include
our third global environmental issues (ozone layer). Since CFCs are no longer
manufactured, our actions as consumers cannot affect this issue as much.
Environmental Impacts per Household
Habitat Alteration
100
90
80
70
60
SO
40
30
20
10
0
Global Air Water
warming pollution pollution
Water Land
i^^-i
iffii|
Bfesf
D Other
^Transportation
g Food
r-i Household
LLJ operations
Adapted from Grower and Leon
According to this study, three
different kinds of activities account
for most of our environmental
impacts as consumers. These are
transportation, food, and household
operations. In other words, we
should pay the most attention to how
we go from place to place, what we
eat, and how we keep our homes
operating (especially heating, cooling,
and lighting). These three kinds of
activities account for about 75% of
our consumer impacts on global
warming, air pollution, water
pollution, and alteration of habitat.
Transportation accounts for 32% of our consumer impacts on global
warming and 51% of our impacts on toxic air pollution. Most of this comes
from our favorite tool and toy, the personal car/light truck. A big part of the
solution is to drive less, and use vehicles that get more miles to the gallon
and release the least pollutants. If we drive a gas guzzler to pick up a gallon
of milk at the market, it does not matter whether we use paper, plastic or no
bag. We created much bigger environmental impacts driving there and back.
Food has enormous environmental impacts, particularly in the areas of water
pollution and habitat alteration. Growing food and grazing livestock occupy
60% of the U.S. land area. Fertilizers, pesticides, animal wastes and erosion
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ActLocaUy
all affect water quality. Brower and Leon recommend that we reduce the
amount of red meat diat we eat. Red meat has much greater environmental
impacts than poultry or grain. Compared to pasta, red meat causes 18 times
as much water pollution and 20 times as much impact on land use. They
also recommend that we eat organic grains, vegetables and fruit. Organic
farming produces less water pollution because it does not use synthetic
fertilizers and pesticides.
Household operations is the third large category of consumer impacts on the
environment. In many of our homes, we burn fossil fuels to heat our living
space and water. We use electricity for these purposes as well as for lighting,
refrigeration and appliances such as the TV, computer and stereo. More
than half die electricity in most countries, including the U.S., comes from
burning fossil fuels, especially coal. And most of our homes use these energy
sources very inefficiently.
Brower and Leon summarize Eleven Priority Actions for American Consumers:
Each of us has to decide how important we think these global and local
environmental issues are, and what we are willing to do about them. I have
shared the study and conclusions from the Union of Concerned Scientists
as one systems-based approach that can help a person choose which actions
can have the most beneficial effects. The next section features two groups
that use systems drinking to make an environmental difference in
their communities.
Ill
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Dr. Art's Guide to Planet Earth
m a k in g a.
difference
Back in 1994, Ray Anderson prepared a speech that changed
his life. More than twenty years earlier, he had founded
Interface, Inc., a company that is the world's largest
producer of commercial floor coverings, making and selling
more than 40% of all the carpet tiles used on Earth. Ray's
speech helped make Interface become much more exciting
than a company that makes rugs for businesses.
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Ray had been asked to talk about his company's environmental vision. In
preparing his speech, he realized that they did not have one. As he read
and explored, he decided to change Interface from a company that was
damaging die environment into one that is restoring it. And to keep making
carpets while increasing sales and profits.
Since then, Interface has used systems thinking to eliminate waste and
pollution. They calculated how much stuff they were taking from the Earth
in order to make their products, and discovered that they were using 1.2
billion pounds of Earth materials, mostly fossil fuels. Ray Anderson says it
made him want to throw up.
Five years later, Interface had reduced waste by about 50% and saved a lot
of money in the process. The company uses at least 5 R's, beginning with
reduce, reuse, and recycle, and adding redesign and renewable energy. Their
newest product will create zero waste and will be produced using solar
power rather than fossil fuels.
A SUSTAINABLE COMPANY
"j , -• ••>."*-••; 3*^.v'.'v'*V^r ••, *.Hs
. .^8£-£s». -vim
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Dr. Art's Guide to Planet Earth
Another redesign feature is that a customer can purchase rug services rather
than rugs. In the old way, a customer buys a rug, and then throws it out
when it needs replacing. In Rays scheme, the customer buys a lease that
provides constant, high quality floor covering. When a rug section needs
replacing, Interface takes out the worn section, replaces it, and completely
recycles it. Zero waste and a better deal for the customer. To quote Ray
Anderson, Interface does well by doing good.
TreePeople in Los Angeles provides another example of a group
that does well by doing good. Founded in 1973, this non-profit
organization supports Los Angeles residents in improving the
neighborhoods in which they live, work and play. Started by a group
of teenagers, Treepeople now has planted over a million and a half
trees in Los Angeles and has one of California's largest environmental
educational programs.
State and federal laws require the Los Angeles county government
to meet a variety of environmental standards (such as clean water,
reduced trash and clean air). TreePeople developed a program for
the L.A. County Department of Public Works to educate and
support teens in improving their local environments. In this
Generation Earth program, they have involved 800,000 high
school students in just two years.
Looking at the urban system, TreePeople selected teens as a target
audience because they can strongly influence their families and
friends, and because the choices they routinely make every day add up to large
environmental impacts. Generation Earth helps teens understand the
environmental systems in which they live and what they can do to protect .them.
The campus water project is one example. Generation Eardi teaches the
water cycle from the points of view of the planet and of Los Angeles.
Students learn where their water comes from and where it goes. Most of
us would think about the water that flows in our faucet's and out of our
homes into the public sanitary sewer system. But another important flow of
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Act Locally
city water occurs outside this system. This is the water that comes from
clouds or garden hoses, and ends up running down our streets, into the
storm drain system and flowing into the ocean.
This urban runoff picks up pollution from car oil, cigarette butts and other
city trash. Unlike the sanitary sewer system, urban runoff is not treated
before it flows into the ocean where it can pollute water and beaches.
Generation Earth students learn these water issues and discover how they
can prevent stormwater pollution. They analyze how their school fits within
this water system and then engage in action projects to minimize the
school's harmful environmental impacts. Projects such as Generation Earth
not only solve problems today, but they also help create future citizens who
have environmental understanding and the skills to make a difference.
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Dr. Art's Guide to Planet Earth
not the
Each of us has strong beliefs and values that guide our
actions. With respect to Earth, one of my values is to leave our
planet in at least as good a condition as I have enjoyed. What
are your values?
I hope this book has given you a simple framework for understanding how
our planet works. .It should also have shown you how complicated the Earth
system is, how much we don't know about such basic issues as the number
of different species or what the climate will be in the next fifty years. If I
don't understand something and my life depends on it, I tend to be cautious
about messing with it. That makes me conclude that we should:
Maintain the current balance
in matter cycles
Avoid interfering with
Earth's energy flows
Preserve the web of life
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You could have a very different value system and reach different conclusions.
I simply ask two things. First, diat you try to understand planet Earth as a
system. Second, if you decide that you want to help protect the Earth
system, then use systems thinking to choose what you do. Every choice we
make has boda good and bad features. Systems thinking can help you
balance those risks and benefits. It can also help you identify the places in
the system where you can have die most effect.
"We can do many things in our daily lives that make a huge difference.
Brower and Leon identified eleven priority actions in die areas of
transportation, food and household operations. I also think that we need
to help make changes in our society diat make it easier for people and
businesses to act in environmentally responsible ways. As one example, it is
usually much more convenient for people to drive their cars than to use
public transportation. Our society has chosen to put more money into
expanding highways than into developing attractive and efficient mass
transit. To have the most effect, we need to combine how we vote in our
daily actions with how we vote in our annual elections.
I hope this book has given you a sense of hope rather than despair. We
cannot destroy life on Earth. Our human ingenuity has brought us to this
unique moment in our development as a species where we can change the
way our planet works. Each of us in our daily lives influences this global
system and our local environment. We do not know what will happen.
I believe that the more we preserve Earth's cycles of matter, flows of energy
and web of life, the more likely are our chances of preserving a hospitable
planet for ourselves, our descendants and all Earth's creatures.
NOT THE END
1*7
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Dr. Art's Guide to Planet Earth
GLJNDEX,
(glossary + index)
Biodiversity - the number and kinds of Earths organisms. We don't know how many
species there are, how many are going extinct today or the consequences for Earth's
web of life p. 66-67, 74-75, 80-85.
Cycles - a repeating pattern such as the seasons of the year. See Chapter 2 for the
rock cycle (p. 20-25), the water cycle (p. 26-33) and the carbon cycle (p. 34-41).
Earth. - a recycling planet powered by the flow of solar energy that supports a networked
web of life. Introduced in Chapter 1 p. 2-17.
Ecosystem - the organisms that live in a particular place, and how they interact with
each other and with their local environment. All ecosystems have a similar pattern
of organization p. 68-75, 83-85, 104-105.
Electromagnetic Spectrum - the very wide range from radio waves (long wavelengths) to
visible light to X-rays and cosmic rays (short wavelength); an important scientific concept
that explains colors and the greenhouse effect p. 50-53.
Energy - a simple word whose scientific definition sounds like a riddle (p. 44). Energy
flows into, through and out of the Earth system p. 12-13, 43-58.
Energy Efficiency - how much value we get from each amount of fuel that we consume.
Today's societies tend to use energy very inefficiently. We can consume much less energy
and still obtain the same services and comfort p. 106-107, 110-111.
Feedback Loops - one way that parts of a system influence each other. Balanced
feedback loops keep systems stable. Reinforcing feedback loops can cause radical change
hi ecosystems p. 71-73, 96-97.
Fossil Fuels - coal, oil and natural gas. Formed from ancient living organisms,
they are a carbon reservoir. Our reliance on fossil fuels as an energy source is increasing the
amount of carbon dioxide in die atmosphere p. 37-41, 106-107, 111, 113.
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Glindex
Global Climate - Earths pattern of temperature and precipitation. Earth's climate has
changed throughout its history. We don't know how much or how fast our activities will
change the global climate p. 57, 79, 82, 92-97.
Greenhouse Effect - specific gases in the atmosphere (especially water and carbon dioxide)
absorb the heat that is leaving the planet and thereby keeps Earth warmer. By burning fossil
fuels and forests, we may have too much of a good thing p. 50-53, 56-57, 95-97? 107,110.
Matter - the stuff that is in our world. On Earth, we encounter it in solid, liquid and gas
forms. Don't be surprised if you walk around muttering "matter cycles, matter cycles,
matter cycles" after reading p. 10-11 and Chapter 2 p. 19-42.
Molecule - matter is made of atoms. A molecule is two or more atoms joined together. The
smallest piece of water is a water molecule, which consists of two hydrogen atoms joined to
one oxygen atom p. 28.
Ozone - a form of oxygen containing three instead of two atoms joined together. Ozone
in the upper atmosphere protects life from the sun's ultraviolet radiation. CFCs and
other chemicals can damage this ozone layer. In the lower atmosphere, ozone is a
pollutant p. 79, 86-91, 100.
Photosynthesis - how Earth's plant life captures solar energy and packages it in sugars; a
part of Earth's carbon cycle that removes carbon dioxide from the atmosphere p. 62-65.
Renewable - sources of energy and materials that can be naturally re-supplied so humans
can take advantage of them without using them up. Examples are sunlight, wind power
and wood p. 107, 113.
Respiration - how organisms release chemical energy from sugars by combining
them with oxygen; a part of Earth's carbon cycle that releases carbon dioxide into
the atmosphere p. 62-65.
System - a whole that is more than the sum of its parts. You, a car and a sandwich are all
examples of systems p. 4-7-
Systems Thinking - a way to understand our world by investigating its systems. Dr. Art
recommends asking three systems questions p. 4-9.
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Dr. Art's Guide to Planet Earth
You're holding the book.
On the web site you can...
• find animations and experiments
• ask questions and get answers
• learn about Dr. Art's show and
when it is happening.
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CHELSEA GREEN
Sustainable living has many facets. Chelsea Greens celebration of the sustainable arts has led us to
publish trend-setting books about organic gardening, solar electricity and renewable energy,
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For more information about Chelsea Green's books on environmental education, or
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Chelsea Green's titles include:
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Believing Cassandra
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Solar Gardening
Straight-Ahead Organic
The Contrary Farmer
The Contrary Farmer's
Invitation to Gardening
Whole Foods Companion
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THE MAN WHO.
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A STORY BY IEAN GIONO
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Dr. Art's Guide to Planet Earth
A El PUT THE AUTHOR
Dr. Art Sussman received his Ph.D. in Biochemistry from Princeton
University. He performed scientific research at Oxford University, Harvard
Medical School and the University of California at San Francisco. For the
past 25 years, he has helped the general public, teachers and students
understand science, especially as it affects them in their daily lives. Dr. Art
works at WestEd (one often regional educational laboratories created by
Congress) to improve science and environmental education at the local,
state and national levels. He uses innovative ways to show that science is
understandable, interesting, relevant and fun.
Special Offer for
Group Purchases
We want to encourage groups to use
Dr. Art's Guide to Planet Earth as part of
their work in improving their communities,
educating teachers, teaching students and
using sustainable business practices.
Examples include:
• Universities or projects that educate
future teachers
• Businesses that want to inform their employees, clients
and/or customers
• Students or community groups involved in
environmental projects
• Schools that teach Earth systems science
Please send an e-mail to planetguide@wested.org. Tell us
how many copies of the book you want and provide a brief
description of your situation/project.. We will offer a group
purchase discount.
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Canada $19.95
"THIS IS AN OlHSmNBl NGiBOQK, Vividly; clearly and concisely
Art Sussman explains how our planet works and what can happen when
the balance of nature is upset;. St will capture the imagination of readers of
all ages and invoice asen^e of wonder. I absolutely-reeoMmend B^Art's
GuidmtofPlanetEarth-It eJeseryes a place not only in every classroom but
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"1 recommend this highly readable book for people of aHages who
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interconnected,"/--' -":•'<•' :•'/••; .' }-• . ; '* - •" -'- --. -•-.--.-"..' - •-''.". -
-. - , - - ' ",' -. , - "-'"-- i - : - - . ' - ' - " -'-'..- , - *• - •' -
AKR^BRUiESfttBERlS^Presidenti National Academy of Sciences
ISBN 1-890132-73-X
•PRl-MfEDON- RECYCLED PAPER
US8NG SOY-BASED JNK
Published by Chelsea Ereeri
/8QO-63S»-4095;
www.chelseagreen.com
9«781890"132736"
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