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What Climate Change
Means for (%hir\
August 2016
EPA 430-F-16-037
Ohio's climate is changing. Most of the state has
warmed by about one degree (F) in the last century.
Floods are becoming more frequent, and ice cover on
the Great Lakes is forming later or melting sooner. In
the coming decades, 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 temperatures 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
Temperature change (°F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Rising temperatures in the last century. All regions of Ohio
have warmed. 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 Ohio. 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, and the amount of water flowing in most streams
during the worst flood of the year has increased by more than
20 percent. During the next century, spring rainfall and average
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.
Ohio River
Flooding occasionally
threatens both navigation
and riverfront communities,
and greater river flows could
make flooding worse. In
2011, a combination of
heavy rainfall and melting
snow caused a flood that
closed the lower Ohio River
to navigation. Heavy rains
and melting snow in March
2015 caused the Ohio
River and its tributaries to flood parts of Cincinnati and Anderson
Although springtime in Ohio is likely to be wetter, summer droughts
are likely to be more severe. Higher evaporation and lower summer
rainfall are likely to reduce river flows. The drought of 2005
caused portions of the lower Ohio River to be closed to commercial
navigation, which delayed shipments of crops and other products
to and from upstream states like Ohio. In 2012, a drought caused
navigation restrictions on the lower Mississippi River, which cost
the region more than $275 million.
One advantage of climate change is that warmer winters reduce
the number of days that ice prevents navigation.

Five inches of rain over 48 hours
flooded Marietta in September 2004.
Credit: National Weather Sen/ice.

Great Lakes
The ice-free season along the Great Lakes is also becoming
longer. Between 1994 and 2011, reduced ice cover lengthened
the shipping season on the 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.
In Lake Erie, the changing climate is likely to harm water quality.
Warmer water tends to cause more algal blooms, which can be
unsightly, harm fish, and degrade water quality. During August
2014, an algal bloom in Lake Erie prompted the City of Toledo to
ban drinking and cooking with tap water. Severe storms also
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 rainstorms could also
cause sewers to overflow into the Great Lakes more often,
threatening beach safety and drinking water supplies.
A satellite view shows ice forming on Lake Erie, particularly at the
western end. In a typical year, nearly the entire surface of the lake
freezes. Credit NOAA CoastWatch.
Changing the climate will have both beneficial and harmful
effects on farming. Longer frost-free growing seasons and
higher concentrations of atmospheric carbon dioxide would
increase yields for some crops during an average year. But
increasingly hot summers are likely to reduce yields of corn
and possibly soybeans. Seventy years from now, Ohio 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
Rising temperatures can harm air quality and amplify existing
threats to human health. Warmer weather can increase the
production of ground-level ozone, a pollutant that causes lung
and heart problems. Ozone also harms plants. In rural Ohio,
ozone levels are high enough to significantly reduce yields of
soybeans and winter wheat. U.S. EPA and the Ohio EPA have
been working to reduce ozone concentrations. As the climate
changes, continued progress toward clean air will become
more difficult.
Hot days can be unhealthy—even dangerous. High air tem-
peratures can cause heat stroke and dehydration, and affect
people's cardiovascular and nervous systems. Northern cities
like Cleveland 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.
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