A	United States
WU^M£l Environmental Protection
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What Climate Change
Means forMgw MeXICO
New Mexico's climate is changing. Most of the
state has warmed at least one degree (F) in the
last century. Throughout the southwestern United
States, heat waves are becoming more common,
and snow is melting earlier in spring. In the coming
decades, our changing climate is likely to decrease
the flow of water in the Colorado, Rio Grande, and
other rivers; threaten the health of livestock; increase
the frequency and intensity of wildfires; and convert
some rangelands to desert.
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 one degree
during the last 80 years. Warming is causing snow to
melt 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. The last decade
was the warmest on record in the Southwest. Source: EPA,
Climate Change Indicators in the United States.
Snowpack
As the climate warms, less precipitation falls as snow, and more snow melts during
the winter. That decreases snowpack—the amount of snow that accumulates over
the winter. Since the 1950s, the snowpack has been decreasing in New Mexico, as
well as in Colorado, Utah, and Wyoming, which matters because the headwaters of
the Rio Grande, San Juan, Colorado, and Navajo rivers are in those states.
Diminishing snowpack in northern New Mexico will 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.
Ski areas like Taos Ski Valley (shown here) depend on seasonal snowpack, which has declined
at all long-term monitoring sites in the Sangre de Crista range. © Chris Lamie; used by
permission.
Water Availability
The changing climate is likely to increase the need for water but reduce the supply.
Warmer temperatures increase the rate at which water evaporates (or transpires)
into the air from soils, plants, and surface waters. Irrigated farmland would thus need
more water. But less water is likely to be available, because precipitation is unlikely
to increase enough to make up for the additional water lost to evaporation. Annual
rainfall is more likely to decrease than increase. So soils are likely to be drier, and
periods without rain are likely to become longer, making droughts more severe.
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 (see map on back page).
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 ecosystems, fish,
water-based recreation, and landowners who draw water directly from a flowing river.

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Snowpack, 1955-2015
Percent Change
Q<-80
Q -80 to-60
O -60 to-40
O -40 to-20
O -5 to-20
o -5 to 5
O 5 to 20
O 20 to 40
O 40 to 60
60 to 80
{ : >80
^^^nColorado River Basin
Trends in April snowpack in New Mexico and Colorado, 1955-2013. The
snowpack has declined at most monitoring sites in both states. Source: EPA.
Agriculture
Increasing droughts and higher temperatures are likely to interfere with
New Mexico's farms and cattle ranches. Hot weather can threaten
cows' health and cause them to eat less, grow more slowly, and
produce less milk. Livestock operations could also be impaired by fire
and changes in the landscape from grassland to woody shrubs more
typical of a desert. Reduced water availability would create challenges
for ranchers, as well as farmers who irrigate fruits, vegetables, pecans,
and other nut trees.
Wildfires and Changing Landscapes
Higher temperatures and drought are likely to increase the severity, fre-
quency, and extent of wildfires, which could harm property, livelihoods,
and human health. On average, more than 2 percent of the land in New
Mexico has burned per decade since 1984. 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 New Mexico's landscape. Many plants
and animals living in arid lands are already near the limits of what they
can tolerate. A warmer and a drier climate would generally extend the
Chihuahuan 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.
In 2012, New Mexico experienced the largest wildfire in the state's recorded
history, the Whitewater-Baldy Complex Fire. Credit: Gila National Forest.
Pests
Warmer, 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 have infested 200,000 acres in
New Mexico. 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.
Extreme Heat
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 dehydration, 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. Warmer air can also increase the formation
of ground-level ozone, a key component of smog. Construction crews
may have to increasingly operate on altered time schedules to avoid the
heat of the day.
Tribal Communities
Climate change threatens natural resources and public health of tribal
communities. Rising temperatures and increasing drought are likely to
decrease the availability of certain fish, game, and wild plants on which
the Navajo and other tribes have relied for generations. Water may be
less available for domestic consumption, especially for those who are
not served by either municipal systems or reliable wells, which
includes about 30 percent of the people on the Navajo Nation, who
must haul water to meet daily needs. Recurring drought and rising
temperatures may also degrade the land itself. On the Arizona portion
of the Navajo Nation, for example, the Great Falls Dune Field has
advanced almost a mile in the last 60 years, threatening roads, homes,
and grazing areas. Extreme heat may also create health problems for
those without electricity, including about 40 percent of the people on
the Navajo reservation.
or ado
New
Mexico
Sources: Esri, DeLorme, USGS, NPS,
Sources: Esri. USGS. NO A A
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. Depiction of trade names does not constitute endorsement of the product. For more information about climate change science,
impacts, responses, and what you can do, visit EPA's Climate Change website at www.epa.aov/climatechanae.

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