Title: Climate Change Impacts in the United States
1Climate Change Impacts in the United States
This section is mainly from Global Climate
Change Impacts in the United States, U.S. Global
Change Research Program, Cambridge University
Press, 2009.
2General National Impacts
3Key National Climate Impacts
- U.S. average temperature has risen more than 2 F
over the past 50 years and is projected to rise
more in the future how much more depends on the
amount of greenhouse gases emitted globally and
how sensitive the climate is to those emissions. - Precipitation has increased an average of about
5 over the past 50 years. Projections of future
precipitation generally indicate that northern
areas will become wetter, and southern areas,
particularly in the West, will become drier. - The amount of rain falling in the heaviest
downpours has increased about 20 on average in
the past century, and this trend is very likely
to continue, with the largest increases in the
wettest places. - Many types of extreme weather events, such as
heat waves and regional droughts, have become
more frequent and intense during the past 40 to
50 years. - The destructive energy of Atlantic hurricanes has
increased in recent decades. The intensity of
these storms is likely to increase in this
century. - In the eastern Pacific, the strongest hurricanes
have become stronger since the 1980s, even while
the total number of storms has decreased. - Sea level has risen along most of the U.S. coast
over the last 50 years, and will continue to rise
in the future. - Cold-season storms tracks are shifting northward
and the strongest storms are likely to become
stronger and more frequent. - Arctic sea ice is declining rapidly and this will
continue.
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10Temperature Change between 1993-2008 (left), and
projected near term between 2010-2029 (right)
11Projected U.S. Temperature Increase (2040-2060)
12Projected temperature increases between 2040-2059
and 2080-2099 for higher emissions scenario (top)
and lower emissions scenario (bottom)
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15U.S. Rainfall Anomaly Jan.-August 2007
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20Increases in Amounts of Very Heavy Precipitation
(1958-2007)
21Change in Hadley Cell Circulation Could Decrease
Winter and Spring Precipitation in the Southwest
- The Hadley Effect The Hadley Cell circulation
illustrates how rising air in the superheated
tropics descends in the subtropics. This creates
high-pressure zones in subtropical regions,
including the U.S. Southwest. - The area under the Hadley cells descending air
is projected to widen in years to come. As a
result, the jet stream that transports rain and
snow during spring and winter is expected to move
toward the North pole. Thus winter storms could
enter the western United States in a more
northerly position, bypassing the Southwest more
often than it currently does.
2243 of U.S. in Drought Conditions in Oct. 2007
23Fires Are Increasing World-Wide
Wildfires in Western U.S. have increased 4-fold
in 30 years.
Western US area burned
Source Westerling et al. 2006
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25Water Resources
26Key Water Resource Impacts
- Climate change has already altered, and will
continue to alter, the water cycle, affecting
where, when and how much water is available for
all uses. - Floods and droughts are likely to become more
common and more intense as regional and seasonal
precipitation patterns change, and rainfall
becomes more concentrated into heavy events (with
longer, hotter dry periods in between). - Precipitation and runoff are likely to increase
in the Northeast and Midwest in winter and
spring, and decrease in the West especially the
Southwest, in the spring and summer. - In areas where snowpack dominates, the timing of
runoff will continue to shift to earlier in the
spring and flows will be lower in late summer. - Surface water quality and groundwater quantity
will be affected by a changing climate. - Climate change will place additional burdens on
already stressed water systems. - The past century is no longer a reasonable guide
to the future for water management.
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28Observed Water-Related Changes During the Last
Century
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30The Southwest Will Have Less Precipitation
- Using an "ensemble" of 18 global climate models
and the moderate "A1B" emissions scenario,
researchers at the NOAA Earth System Research
Laboratory (ESRL) predict a reduction in
precipitation across the Southwest by the end of
the century. - Credit Map produced by Jeremy Weiss of the
University of Arizona, using data from Hoerling
and Eischeid of NOAA ESRL. http//www.noaa.gov/
31Drought on the Southwest, U.S.
32Increases in Amounts of Very Heavy Precipitation
(1958-2007)
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34Trends in Peak Streamflow Timing
35Potential Water Supply Conflicts by 2025
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37Highlights of Water-related Impacts by Sector
38Energy Supply and Use
39Key Energy Supply and Use Impacts
- Warming will be accompanied decreases in demand
for heating energy and increases in demand for
cooling energy. The later will result in
significant increases in electricity use and
higher peak demand in most regions. - Energy production is likely to be constrained by
rising temperatures and limited water supplies in
many regions. - Energy production and delivery systems are
exposed to disruption by sea level rise and
extreme weather events in vulnerable regions. - Climate change is likely to affect some renewable
energy sources across the nation, such as
hydroelectric power production in regions subject
to changing patterns of precipitation or snowmelt.
40Sources of U.S Greenhouse Gas Emissions (2003)
41Primary Energy Consumption by Major Source
(1949-2007)
42U. S. Electricity Sources (2007)
43Population Change (1970-2008)
44Shifting Energy Demand in the U. S. by 2080-2099.
45Significant Weather-related U.S. Electric Grid
Disturbances
46Transportation
47Key Transportation Impacts
- Sea level rise and storm surge will increase the
risk of major coastal impacts, including both
temporary and permanent flooding of airports,
roads, rail lines, and tunnels. - Flooding from increasingly intense downpours will
increase the risk of disruptions and delays in
air, rail and road transportation, and damage
from mudslides in some areas. - The increase in extreme heat will limit some
transportation operations and cause pavement and
track damage. Decreased extreme cold will provide
some benefits such as reduced snow and ice
removal costs in some areas. - Increased intensity of strong hurricanes would
lead to more evacuations, infrastructure damage
and failure, and transportations disruptions. - Arctic warming will continue to reduce sea ice,
lengthening the ocean transport season, but also
resulting in greater coastal erosion due to
waves. Permafrost thaw in Alaska will damage
infrastructure. The ice road season will become
shorter.
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49Agriculture
50Key Agriculture Impacts
- Many crops show positive responses to elevated
CO2 and low levels of warming, but higher levels
of warming often negatively affect growth and
yields. - Extreme events such as heavy downpours and
droughts are likely to reduce crop yields because
excesses or deficits of water have negative
impacts on plant growth. - Weeds, diseases, and insect pests benefit from
warming, and weeds also benefit from a higher CO2
concentrations, increasing stress on crop plants
and requiring more attention to pest and weed
control. - Forage quality in pastures and rangelands
generally declines with increasing CO2
concentration because of the effects on plant
nitrogen and protein content, reducing the lands
ability to supply adequate livestock feed. - Increased heat, disease, and weather extremes are
likely to reduce livestock and agricultural
productivity.
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58Ecosystems
59Key Ecosystem Impacts
- Ecosystem processes, such as those that control
growth and decomposition, have been affected by
climate change. - Large-scale shifts have occurred in the ranges of
species and the timing of the seasons and animal
migration, and are very likely to continue. - Fires, insect pests, disease pathogens, and
invasive weed species have increased, and these
trends are likely to continue. - Deserts and drylands are likely to become hotter
and drier, feeding a self-reinforcing cycle of
invasive plants, fire, and erosion. - Coastal and near-shore ecosystems are already
under multiple stresses. Climate change and ocean
acidification will exacerbate these stresses. - Arctic sea ice ecosystems are already being
adversely affected by the loss of summer sea ice
and further changes are expected. - The habitats of some mountain species and
coldwater fish, such as salmon and trout, are
very likely to contract in response to warming. - Some of the benefits ecosystems provide to
society will be threatened by climate change,
while others will be enhanced.
60Butterfly Range Shifts Northward
- As the climate warms, many species in the United
States are shifting their ranges northward and to
higher elevations. The map show the response of
Ediths Checkerspot butterfly populations to a
warming climate over the past 136 years in the
American West. Over 70 of the southernmost
populations (shown in yellow) have gone extinct.
The northernmost populations and those above
8,000 feet elevation in the cooler climate of
Californias Sierra Nevada (shown in green) are
still thriving. These differences in numbers of
population extinctions across the geographic
range of the butterfly have resulted in the
average location shifting northward and to higher
elevations over the past century, illustrating
how climate change is altering the ranges of many
species. Because their change in range is slow,
most species are not expected to be able to keep
up with the rapid climate change projected in the
coming decades.
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65Human Health
66Key Health Impacts
- Increases in the risk of illness and death
related to extreme heat and heat waves are very
likely. Some reduction in the risk of death
related to extreme cold is expected. - Warming is likely to make it more challenging to
meet air quality standards necessary to protect
public health. - Extreme weather events cause physical and mental
health problems. Some of these events are
projected to increase. - Some diseases transmitted by food, water, and
insects are likely to increase. - Rising temperature and CO2 concentrations
increase pollen production and prolong the pollen
season in a number of plants with highly
allergenic pollen, presenting a health risk. - Certain groups, including children, the elderly,
and the poor, are most vulnerable to a range of
climate-related health effects.
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68Number of Days Over 100 F
- The number of days in which the temperature
exceeds 100 F by late this century, compared to
the 1960s and 1970s, is projected to increase
strongly across the United States. For example,
parts of Texas that recently experienced about 10
to 20 days per year over 100 F are expected to
experience more than 100 days per year in which
the temperature exceeds 100 F by the end of the
century under the higher emissions scenario.
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75Occurrence of the Dengue Fever Vector Mosquito
and Number of Suspected Cases in Each State
76Society
77Key Society Impacts
- Population shifts and development choices are
making more Americans vulnerable to the expected
impacts of climate change. - Vulnerability is greater for those who have few
resources and few choices. - City residents and city infrastructure have
unique vulnerabilities to climate change. - Climate change affects communities through
changes in climate-sensitive resources that occur
both locally and at great distances. - Insurance is one of the industries particularly
vulnerable to increasing extreme weather events
such as severe storms, but it can also help
society mange the risks. - The United States is connected to a world that is
unevenly vulnerable to climate change and thus
will be affected by impacts in other parts of the
world.
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