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S&faiMl'r»jOk Environmental Protection
L Agency
August 2016
EPA 430-F-16-046
What Climate Change
Means for (Jtall
Utah's climate is changing. The state has warmed
about two degrees (F) in the last century. Throughout
the western United States, heat waves are becoming
more common, and snow is melting earlier in spring.
In the coming decades, the changing climate is
likely to decrease the flow of water in Utah's rivers,
increase the frequency and intensity of wildfires, and
decrease the productivity of ranches and farms.
Our climate is changing because 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, aver-
age 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.
As the climate warms, less precipitation falls as snow, and more snow melts
during the winter. That decreases snowpack—the amount of snow that accu-
mulates over the winter. Since the 1950s, the snowpack has been decreasing
in Utah, as well as Wyoming and Colorado, which contribute snowmelt to the
Green and Colorado rivers.
Diminishing snowpack can shorten the season for skiing and other forms of
winter tourism and recreation. The tree line may shift, as subalpine fir and other
high-altitude trees become able to grow at higher elevations. A higher tree line
would decrease the extent of alpine tundra ecosystems, which could threaten
some species.
A surveyor measures the depth of the snowpack at Mi Baldy on the Wasatch Plateau in
April 2015. The map below shows the results of many years of this type of measurement.
Credit: Jordan Clayton, USDA Natural Resources Conservation Service.
Temperature change (F):
-1 -0 5 6 0.5 1 1.5 2 2 5 3 7.5
Rising temperatures in the last century. The last decade was the
warmest on record throughout the West. Source; EPA, Climate
Change Indicators in the United States.
Nell is Air ,
orce Range
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Snowpack, 1955-2015
COI O R A n Famujigton
Sources: Esri, DeLorme, USGS, NPS,
Sources: Esri. USGS. NOAA
-80 to -60
-60 to -40
-40 to -20
-5 to -20
-5 to 5
5 to 20
20 to 40
40 to 60
60 to 80
Trends in April snowpack, 1955-2013. Snowpack has declined at most monitoring sites in Utah
and the Upper Colorado River Basin. Source: EPA.

Water Availability
The changing climate is likely to increase the need for water but
reduce the supply. Rising temperatures increase the rate at which
water evaporates (or transpires) into the air from soils, plants, and
surface waters. Soils are likely to be drier in most of the state, so
irrigated farmland would need more water. But less water is likely
to be available, because precipitation is unlikely to increase as
much as evaporation.
The decline in snowpack could further limit the supply of water for
some purposes. Mountain snowpacks are natural reservoirs. They
collect the snow that falls during winter and release water when
the snow melts during spring and summer. Over the past 50 years,
snowpack has been melting earlier in the year. Dams capture most
meltwater and retain it for use later in the year. But upstream of
these reservoirs, less water is available during droughts for eco-
systems, fish, water-based recreation, and landowners who draw
water directly from a flowing river.
Increasing droughts and higher temperatures are likely to interfere
with Utah's farms and cattle ranches. Hot temperatures threaten
cows' health and cause them to eat less, grow more slowly, and
produce less milk. Fire may also impair livestock operations.
Reduced water availability would create challenges for ranches and
irrigated farms, which account for 80 percent of the water used in
the state.
Wildfires and Changing Landscapes
Higher temperatures and drought are likely to increase the severity,
frequency, and extent of wildfires, which could harm property,
livelihoods, and human health. The Milford Flat Fire in 2007 was the
largest wildfire ever recorded in Utah. Wildfire smoke can reduce
air quality and increase medical visits for chest pains, respiratory
problems, and heart problems.
The combination of more fires and drier conditions may expand
deserts and otherwise change parts of Utah's landscape. Many
plants and animals living in arid lands are already near the limits of
what they can tolerate. Higher temperatures and a drier climate
would generally extend the Great Basin desert to higher elevations
and expand its geographic range. In some cases, native vegetation
may persist and delay or prevent expansion of the desert. In other
cases, fires or livestock grazing may accelerate the conversion of
grassland to desert in response to the changing climate. For
similar reasons, some forests may change to desert or grassland.
Warmer and drier conditions make forests more susceptible to
pests. Drought reduces the ability of trees to mount a defense
against attacks from pests such as bark beetles, which infested
50,000 acres of Utah's forests in 2012. Temperature controls the
life cycle and winter mortality rates of many pests. With higher
winter temperatures, some pests can persist year-round, and new
pests and diseases may become established.
In Utah's Uinta-Wasatch-Cache National Forest, bark beetles have killed more
than 90 percent of the trees in some areas. Credit: Brendan Waterman, USDA
Forest Service.
Human Health
Hot days can be unhealthy—even dangerous. Certain people are
especially vulnerable, including children, the elderly, the sick, and
the poor. High air temperatures can cause heat stroke and dehy-
dration, and affect people's cardiovascular, respiratory, and nervous
systems. Higher temperatures are amplified in urban settings where
paved and other surfaces tend to store heat. Construction crews
may have to alter their work schedules to avoid the heat of the day.
Rising temperatures can also increase the formation of ground-
level ozone, a key component of smog. Ozone has a variety of
health effects, aggravates lung diseases such as asthma, and
increases the risk of premature death from heart or lung disease.
EPA and the Utah Department of Environmental Quality have been
working to reduce ozone concentrations. As the climate changes,
continued progress toward clean air will be more difficult.
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
at vmw.epa.aov/climatechanae.