rnA United States	AugUSt2016
MKU Environmental Protection
WLJ Agency	EPA 430-F-16"049
What Climate Change
mm	r ¦ ¦ ¦	M ¦
Means
Washington

Washington's climate is changing. Over the past century,
most of the state has warmed one to two degrees (F).
Glaciers are retreating, the snowpack is melting earlier in
the year, and the flow of meltwater into streams during
summer is declining. In the coming decades, coastal
waters wiil become more acidic, streams will be warmer,
populations of several fish species will decline, and
wildfires may be more common.
Our climate is changing because the earth is warming.
People have increased the amount of carbon dioxide in
the air by 40 percent since the late 1700s. Other heat-
trapping greenhouse gases are also increasing. These
gases have warmed the surface and lower atmosphere
of our planet about one degree during the last 50 years.
Evaporation increases as the atmosphere warms, which
increases humidity, average rainfall, and the frequency of
heavy rainstorms in many places—but contributes to
drought in others.
Greenhouse gases are also changing the world's oceans
and ice cover. Carbon dioxide reacts with water to form
carbonic acid, so the oceans are becoming more acidic.
The surface of the ocean has warmed about one degree
during the last 80 years. Warming is causing snow to melt
earlier in spring, and mountain glaciers are retreating.
Even the great ice sheets on Greenland and Antarctica are
shrinking. Thus the sea is rising at an increasing rate.
Temperature change (F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Rising water temperatures, increasing ocean acidity,
and changes in the marine ecosystem will amplify
observed losses in commercially and recreationally
important fish stocks in the region in the 2 f century.
Credit: NOAA.
Marine and Coastal Ecosystems
Washington's coastal
waters are vulnerable to
acidification. The ocean
here is more acidic
than most of the ocean,
because nearby currents
bring relatively acidic
water from the deep ocean
to the surface, especially
during spring and summer.
Increasing acidity impairs
the ability of some types of
shellfish to capture miner-
als in the water to build their shells, which can lead to thinner shells—or
even prevent shells from forming. Oyster hatcheries in Washington are
becoming less productive, because the water they draw from along the
shore has become more acidic and corrosive, partly because of higher
atmospheric carbon dioxide. Acidity also thins the exoskeietons of many
species of plankton, which could reduce the population of those plankton
and the fish that feed on them, and alter the entire marine food web. For
example, young salmon eat some of the types of shellfish and plankton
that are vulnerable to acidification.
Rising ocean temperatures may also harm marine ecosystems. Warming
waters can increase the frequency of toxic algae blooms (such as "red
tide") that cause shellfish poisoning and lead to closures of beaches and
shellfish beds. Warmer waters also allow invasive species from southern
waters to move northward.


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Rising temperatures in the last century The warming in Washington has
been similar to the average warming nationwide. Source: EPA, Climate
Change Indicators in the United States.
Pteropods, or "sea butterflies," are small free-swimming sea snails. They are an
important source of food for North Pacific juvenile salmon, as well as whales and other
marine species. The left panel shows a shell collected from a live pteropod from a region
where acidity is not yet very high. The shell on the right is from a pteropod collected in a
region where waters have acidified. Credit: Nina Bednarsek, NOAA.

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Impacts of Sea Level Rise
Sea level rise will threaten coastal development and ecosystems.
Erosion will threaten homes and public property along the shore.
Increased flooding could threaten wastewater treatment plants,
ferry terminals, highways, and railroads along Puget Sound.
Mudflats, marshes, and other tidal wetlands provide habitat for
birds and fish. As water levels rise, wetlands may be submerged
or squeezed between the rising sea and structures built to protect
coastal development.
Glacial Retreat
Three thousand glaciers cover about 170 square miles of mountains
in Washington, but that area is decreasing in response to warmer
temperatures. For example, South Cascade Glacier has decreased
in size since the 1950s, with an accelerated rate of decline in recent
years.
-•?
Aerial views of South Cascade Glacier in September 1955 (left) and September
2004 (right). Credits: Austin Post, USGS (left); © John Scuriock, used by
permission (right).
Snowpack, Streamflows, and Water Availability
The flows of water in rivers and streams are increasing during late
winter and early spring but decreasing during summer. Warmer
winters have reduced average snowpack in Washington by
20 percent since 1950. The snowpack is now melting a few
weeks earlier than during the 20th century, and, by 2050, it is likely
to melt three to four weeks earlier. Decreasing snowpack means
there will be less water flowing through streams during summer.
Moreover, rising temperatures increase the rate at which water
evaporates (or transpires) into the air from soils and plants. More
evaporation means that less water will drain from the ground into
rivers and streams.
Declining snow and streamflow would harm some economic
sectors and aquatic ecosystems. Less snow means a shorter
season for skiing and other winter recreation. Water temperatures
will rise, which would hurt Chinook and sockeye salmon in the
interior Columbia River Basin. The combination of warmer water
and lower flows would threaten salmon, steelhead, and trout. Lower
flows would also mean less hydroelectric power.
Drought and Wildfires
Changing the climate is likely to more than double the area in the
Northwest burned by forest fires during an average year by the end
of the 21st century. Although drier soils increase the risk of wildfire,
other factors also contribute to fires, and forests in the Western
Cascades may be less vulnerable to climate change than those in
the Eastern Cascades. Higher temperatures and a lack of water can
also make trees more susceptible to pests and disease, and trees
damaged or killed burn more readily than living trees. Changing
climate is likely to increase the area of pine forests in the Northwest
infested with mountain pine beetles over the next few decades. Pine
beetles and wildfires are each likely to decrease timber harvests.
Increasing wildfires also threaten homes and pollute the air.
Agriculture
The changing climate will affect Washington's agricultural sector,
particularly fruits and vegetables, which often require irrigation.
Because streams rather than ground water provide most of
Washington's irrigation water, the expected decline in streamflow
would reduce the water available for irrigation. About two-thirds of
the nation's apples come from Washington, and most are grown
east of the Cascade Mountains where the dry climate requires
irrigation. The Washington Department of Ecology is concerned that
yields of apples and cherries may decline in the Yakima River Basin
as water becomes less available. Alfalfa, potato, and wheat farmers
also require substantial irrigation.
Health and Vulnerable People
Climate change is likely to amplify some threats to health in
Washington. Certain people are especially vulnerable, including
children, the elderly, the sick, and the poor.
The sources of information about climate and the impacts of climate change in this publication are: the national climate assessments by the U.S. Global Change Research Program,
assessment reports by the Intergovernmental Panel on Climate Change, and EPA's Climate Change Indicators in the United States. Mention of a particular season, location, species,
or any other aspect of an impact does not imply anything about the likelihood or importance of aspects that are not mentioned. For more information about climate change science,
impacts, responses, and what you can do, visit EPA's Climate Change website at www.epa.gov/climatechanae.

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