r-r~U\ United States
Environmental Protection
% W i-=s Agency
August 2016 ^
EPA 430-F-16-029
What Climate Change

Meansfor Nebraska

Nebraska's climate is changing. In the past
century, most of the state has warmed by
at least one degree (F). The soil is becoming
drier, and rainstorms are becoming more
intense. In the coming decades, flooding is
likely to increase, yet summers are likely to
become increasingly hot and dry, which would
reduce yields of some crops, require farmers
to use more water, and amplify some risks to
human health.
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.
Temperature change ( F):
-1 -0.5 0 0.5 1 1.5 2 2.5 3 3.5
Rising temperatures in the last century. The
Panhandle has wanned more than the rest of
Nebraska. Source: EPA, Climate Change Indicators in
the United States.
Precipitation and Water Resources
Changing the climate is likely to increase the demand for water but make
it less available. Soils will probably continue to become drier, because
warmer temperatures increase evaporation and water use by plants, and
average rainfall during summer is likely to decrease. More evaporation
and less rainfall would reduce the average flow of rivers and streams.
Decreased river flows can create problems for navigation, recreation,
public water supplies, and electric power generation. Commercial
navigation can be suspended during droughts (or floods) when there is
too little water to keep channels deep enough for barge traffic. Decreased
river flows can also lower the water level in lakes and reservoirs, which
may limit municipal water supplies and impair swimming, fishing, and
other recreational activities. Lower flows during a summer drought can
reduce hydroelectric power generation at a time of year when warmer
temperatures increase the demand for electricity for air conditioning.
Conventional power plants also need adequate water for cooling.
Higher temperatures
and drier soils are likely
to increase the use of
water by more than
25 percent during the
next 50 years, mostly
because of increased
irrigation. Approximately
one-third of the farmland
in Nebraska is irrigated
with ground water, most
of which comes from
the High Plains Aquifer
System, and municipal
water supplies also reply primarily on ground water. In Nebraska, the
aquifer is only being depleted in a few western areas. But water levels are
declining throughout much of Kansas, where the average temperature
today is similar to what the average temperature of Nebraska is likely to
be 70 to 100 years from now.
The severe drought of 2012 led to low flow in
rivers across Nebraska. This photo shows the
nearly dry riverbed of the Big Nemaha River
near Falls City. Credit: Mike Andersen, USGS.

Rising temperatures and changes in rainfall are likely to have
both negative and positive effects on Nebraska's farms and
ranches. Hot weather causes cows to eat less and grow more
slowly, and it can threaten their health. Increased winter and
spring precipitation could leave some fields too wet to plant,
and warmer winters may promote the growth of weeds and
pests. Hotter summers and drier soils would cause droughts to
become more intense. Over the next 70 years, the number of
days per year above 100°F is likely to double. Increased
drought, along with a greater number of extremely hot days,
could cause crop failures. Even where ample water is
available, higher temperatures would reduce yields of corn.
Increased concentrations of carbon dioxide, however, may
increase yields of wheat and soybean enough to offset the
impact of higher temperatures. Warmer and shorter winters
may allow for a longer growing season, which could allow two
crops per year instead of one in some instances. Increased
precipitation at the beginning of the growing season could also
be beneficial to some crops.
Rainstorms and Tornadoes
Although summer droughts are likely to become more severe,
floods may also intensify. During the last 50 years, the amount
of rain falling during the wettest four days of the year has
increased about 15 percent in the Great Plains. River levels
during floods have become higher in eastern Nebraska. Over
the next several decades, heavy downpours will account for an
increasing fraction of all precipitation, and average precipita-
tion during winter and spring is likely to increase. Both of these
factors would further increase flooding.
Scientists do not know how the frequency and severity of
tornadoes will change. Rising concentrations of greenhouse
gases tend to increase humidity, and thus atmospheric
instability, which would encourage tornadoes. But wind shear
is likely to decrease, which would discourage tornadoes.
The Foil Calhoun Nuclear Power Plant in eastern Nebraska was
surrounded by a Missouri River flood in June 2011, Credit: U.S. Army
Corps of Engineers.
Research is ongoing to learn whether tornadoes will be more
or less frequent in the future. Because Nebraska experiences
more than 50 tornadoes a year, such research is closely
followed by meteorologists in the state.
Human Health
Hot days can be unhealthy—even dangerous. Certain people
are especially vulnerable, including children, the elderly, the
sick, and the poor. The elderly may be particularly prone to
heat stress and other heat-related health problems, including
dehydration, cardiovascular strain, and respiratory problems.
Those with low incomes may be particularly vulnerable due
to a lack of air conditioning. Power failures due to severe
weather can also present risks, especially in lightly populated
areas where access to the necessary support services may
be limited. Climate change may also increase the length and
severity of the pollen season for allergy sufferers. For example,
the ragweed season near Omaha has grown 10 days longer
since 1995, because the first frost in fall is later.
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.