United States
Environmental Protection
kAgency
August 2016
EPA 430-F-16-025
What Climate Change
Meansfor Minnesota
Minnesota's climate is changing. The state has warmed
one to three degrees (F) in the last century. Floods are
becoming more frequent, and ice cover on lakes is forming
later and melting sooner. In the coming decades, these
trends are likely to continue. Rising temperatures may
interfere with winter recreation, extend the growing season,
change the composition of trees in the North Woods, and
increase water pollution problems in lakes and rivers. The
state will have more extremely hot days, which may harm
public health in urban areas and corn harvests in rural
areas.
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 also warmed about one
degree during the last 80 years. Although warmer tempera-
tures cause sea level to rise, the impact on water levels in
the Great Lakes is not yet known. Warmer air also melts ice
and snow earlier in spring.
Temperature change (°F):
-1 -0.5 0 0.5 1 1.5 2 2,5 3 3.5
Rising temperatures in the last century. Northern Minnesota
has warmed more than twice as much as southern Minnesota.
Source: EPA, Climate Change Indicators in the United States.
Heavy Precipitation and Flooding
Changing the climate is likely to increase the frequency of floods in Minnesota.
Over the last half century, average annual precipitation in most of the Midwest
has increased by 5 to 10 percent. But rainfall during the four wettest days of
the year has increased about 35 percent. During the next century, spring
rainfall and annual precipitation are likely to increase, and severe rainstorms
are likely to intensify. Each of these factors will tend to further increase the risk
of flooding.
Lakes and Rivers
Flooding is occasionally
a problem for both
navigation and riverfront
communities, and greater
river flows could make
these problems worse. In
the Red River watershed,
river flows during the
worst flood of the year
have been increasing
about 10 percent per
decade since the 1920s.
Floods are also becoming
more severe in the upper
Mississippi watershed. In
June 2014, a flood forced two port facilities in St. Paul to stop operating, and
barges waiting to unload had to be temporarily parked in Pigs Eye Lake until
the river receded. Increasingly severe droughts elsewhere in the Mississippi
River Basin could also pose problems for navigation in Minnesota. For
example, a drought in 2012 led the U.S. Army Corps of Engineers to restrict
navigation on the lower Mississippi River, which affected shipping upstream.
One advantage of climate change is that warmer winters reduce the number
of days that ice prevents navigation. Between 1994 and 2011, the decline in
ice cover lengthened the shipping season on the Great Lakes by eight days.
The Great Lakes are likely to warm another 3° to 7°F in the next 70 years,
which will further extend the shipping season.
Higher temperatures and heavier storms could harm water quality in
Minnesota's lakes and rivers. Warmer water tends to cause more algal
blooms, which can be unsightly, harm fish, and degrade water quality. Severe
storms increase the amount of pollutants that run off from land to water, so
the risk of algal blooms will be greater if storms become more severe.
Increasingly severe storms could also cause sewers to overflow into lakes or
rivers more often, threatening beach safety and drinking water supplies.
-i'
Flooding of the Red River in East Grand Forks in
1997. Credit: Dave Saville, FEMA.

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Ecosystems
The ranges of plants and animals are likely to shift as the climate
changes. For example, warmer weather could change the composition
of Minnesota's forests. As the climate warms, the populations of paper
birch, quaking aspen, balsam fir, and black spruce trees may decline in
the North Woods, while oak, hickory, and pine trees may become more
numerous. Climate change will also transform fish habitat. Rising water
temperatures will increase the available habitat for warmwater fish
such as bass, while shrinking the available habitat for coldwater fish
such as trout. Declining ice cover and increasingly severe storms
would harm both types offish habitat through erosion and flooding.
Warming could also harm ecosystems by changing the timing of natural
processes such as migration, reproduction, and flower blooming.
Migratory birds are arriving in Minnesota earlier in spring today than
40 years ago. Along with range shifts, changes in timing can disrupt
the intricate web of relationships between animals and their food
sources and between plants and pollinators. Because not all species
adjust to climate change in the same way, the food that one species
eats may no longer be available when that species needs it (for
example, when migrating birds arrive). Some types of animals may no
longer be able to find enough food.
Winter Recreation
Warmer winters are likely to shorten the season for recreational activ-
ities like ice fishing, snowmobiling, skiing, and snowboarding, which
could harm the local economies that depend on them. Small lakes are
freezing later and thawing earlier than a century ago, which shortens
the season for ice fishing and ice skating. Since the early 1970s,
winter ice coverage in the Great Lakes has decreased by 63 percent.
Warmer temperatures are likely to shorten the season when the ground
is covered by snow, and thereby shorten the season for activities that
take place on snow. Nevertheless, annual snowfall has increased in
much of the Great Lakes region, which could benefit winter recreation
at certain times and locations.
Agriculture
Changing the climate is likely to have both positive and negative effects
on agriculture in Minnesota. Warmer weather has extended the growing
season by about 15 days since the beginning of the 20th century.
Longer frost-free growing seasons and higher concentrations of
atmospheric carbon dioxide would increase yields of soybeans and
wheat during an average year. But increasingly hot summers may
reduce yields of corn. In seventy years, southern Minnesota is likely to
have 5 to 15 more days per year with temperatures above 95°F than it
has today. More severe droughts or floods would also hurt crop yields.
Air Pollution and Human Health
Changing the climate can harm air quality and amplify existing threats
to human health. Higher temperatures increase the formation of
ground-level ozone, a pollutant that causes lung and heart problems.
Ozone also harms plants. In some rural parts of Minnesota, ozone
levels are high enough to reduce yields of soybeans and winter
wheat. EPA and the Minnesota Pollution Control Agency have been
working to reduce ozone concentrations. As the climate changes,
continued progress toward clean air will become more difficult.
Climate change may also increase the length and severity of the pollen
season for allergy sufferers. For example, the ragweed season in Min-
neapolis is 21 days longer than in 1995, because the first frost in fall is
later. The risk of some diseases carried by insects may also increase.
The ticks that transmit Lyme disease are active when temperatures
are above 45°F, so warmer winters could lengthen the season during
which ticks can become infected or people can be exposed to the ticks.
Hot days can be unhealthy, even dangerous. High air temperatures can
cause heat stroke and dehydration, and affect people's cardiovascular
and nervous systems. Northern cities like Minneapolis and St. Paul
are vulnerable to heat waves, because many houses and apartments
lack air conditioning, and urban areas are typically warmer than their
rural surroundings. In recent decades, severe heat waves have killed
hundreds of people across the Midwest. Heat stress is expected to
increase as climate change brings hotter summer temperatures and
more humidity. Certain people are especially vulnerable, including
children, the elderly, the sick, and the poor.
A photo of a ragweed plant, a common source of allergens in
Minnesota. Like many crops and pollen sources, ragweed will have a
longer growing season as temperatures rise. Stock photo.
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, synthesis and assessment products by the U.S. Climate Change Science 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 atwww.epa.gov/climatechanae.

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