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Executive Summary
In the summer of 2006, Americans from coast to coast experienced a
sweltering heat wave that broke more than 2,300 daily temperature records in
July alone. This record warmth, however, was not an anomaly; rather, it is
indicative of a broader trend toward increasing temperatures and extreme
weather resulting from global warming. To examine recent trends in temperature
in cities and towns across the United
States, this report analyzes 2000-2006
temperature data from 255 major weather stations and finds that temperatures
were above normal almost everywhere during the period.
Average temperatures worldwide have risen by 0.8° C (1.44° F) in the past
century and now are increasing at a rate of about 0.2° C (0.36° F) per decade.
The 10 warmest years of the global record have all occurred since 1990, and
2005 was the warmest year to date.
The consensus view of the scientific community is that most of the global
warming that has occurred is due to human activities, particularly the burning
of fossil fuels. Fossil fuel combustion releases carbon dioxide, which traps
radiation emitted from the earth’s surface that normally would escape back to
space. Since 1750, the concentration of carbon dioxide in the atmosphere has
increased by 35%.
The United States
emits far more carbon dioxide than any other nation in the world. Emissions of
carbon dioxide in the United
States – primarily from electric power
plants and passenger vehicles – have nearly doubled since 1960 and are
projected to increase dramatically in the years to come.
In the continental United
States, the first seven months of 2006 were
the warmest January-July of any year on record. The average temperature was
55.3° F, or 3.2° F above the 20th century average. Every state in the
continental United States
experienced warmer-than-average temperatures; in most states, temperatures were
much warmer than the 20th century average. For instance, according to the National Climatic Data
Center:
• Five states experienced their warmest January-July on record (Kansas, Missouri, Oklahoma, South Dakota,
and Texas).
• Eleven states experienced their second warmest January-July on
record (Illinois, Maine, Minnesota, Montana, Nebraska, New Hampshire,
New Jersey, New Mexico,
North Dakota, Vermont,
and Wyoming).
• The average temperature for the first seven months of 2006 ranged between
4.0° F and 6.6° F above the 20th century average in Iowa,
Kansas, Minnesota,
Missouri, Montana,
Nebraska, North Dakota,
Oklahoma, South Dakota,
Wisconsin, and Wyoming.
To examine how recent U.S.
temperature patterns compare with temperatures over the last 30 years, we
analyzed temperature data from “First Order” weather stations for the years
2000-2005 and the first six months of 2006. First Order stations are those
staffed in whole or in part by National Weather Service personnel and therefore
provide the highest quality data. The 255 stations are located in all 50 states
and Washington, DC. We compared this recent data to
historical, or “normal,” data from the stations for the three decades spanning
1971-2000.
Overall, we found that temperatures were above normal across the country,
indicating pervasive warming. Specifically:
Average Temperatures Rising
• Between 2000 and 2005, the average temperature was above normal at 95% of
the locations we studied. Alaska
experienced the most warming on average, with Talkeetna reporting average
temperatures 4.6° F above normal. Outside of Alaska,
weather stations in Colorado, Michigan, Montana, Nevada and Wyoming
reported the highest above-normal temperatures for the period.
• During the first six months of 2006, the average temperature was above
normal at 91% of the locations. The average temperature was at least 3° F above
normal in 43% of the locations and at least 5° F above normal in 12 of the
locations. Temperatures were particularly warm in Texas
and the Great Plains states. The average
temperature was nearly 5.9° F above normal, the highest in the country, in Kansas City, Missouri and
5.6° F above normal in Wichita Falls,
Texas.
Nights Getting Warmer
• Between 2000 and 2005, the average minimum (nighttime low) temperature was
above normal at 92% of the locations. The average minimum temperature in Reno, Nevada was 5.2° F
above normal, the highest in the United States. Albuquerque, New Mexico
recorded average minimum temperatures of more than 3° F above normal.
• During the first six months of 2006, the average minimum (nighttime low)
temperature was above normal at 87% of the stations. The average minimum
temperature was at least 3° F above normal in 28% of the locations and at least
5° F above normal in nine of these locations. Nighttime temperatures were
particularly mild on average in the upper Midwest, with temperatures soaring to
6.7° F above normal in Sioux Falls, South Dakota and almost 6° F above normal in
Minneapolis-St. Paul, Duluth, Rochester,
and St. Cloud, Minnesota.
Days Getting Warmer
• Between 2000 and 2005, the average maximum (daytime high) temperature was
above normal at 80% of the locations. Alaska
experienced the most daytime warming. Locations outside of Alaska
experiencing the highest abovenormal average maximum temperatures include Goodland, Kansas; Alamosa
and Pueblo, Colorado;
Brownsville, Texas;
and Rapid City, South Dakota.
• During the first six months of 2006, the average maximum temperature was
above normal at 87% of the locations. The average maximum temperature was at
least 3° F above normal in 39% of the locations and least 5° F above normal in
28 of these locations. Warmer-thannormal days hit Texas
and the Great Plains the most, averaging more than 6° F above normal in Dodge City, Concordia, and Wichita,
Kansas as well as Grand
Island, Nebraska and Oklahoma City, Oklahoma.
To curb global warming and protect future generations, the United States
should adopt a series of public policies designed to quickly and significantly
reduce emissions of global warming pollutants from power plants, cars and
trucks, and manufacturing facilities.
Cap global warming emissions. The United States should establish
mandatory, sciencebased limits on carbon dioxide and other global warming
pollutants that reduce emissions from today’s levels within 10 years, by 15-20%
by 2020, and by 80% by 2050. Adopt complementary clean energy policies to
reduce global warming emissions. To achieve these reductions, the United States
should adopt strong policies to improve the efficiency with which we use fossil
fuels and increase our use of clean, renewable energy.
Encourage action at the state level. Federal action to reduce global warming
pollution should promote innovative approaches at the state level and not
impede individual states or groups of states from pursuing policies that go
above and beyond the commitments made by the federal government.
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