Global Warming Reports
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Executive Summary
Executive Summary
Globally, the year 2007 tied for the
second warmest year on record, behind the record warmth of 2005. This
warmth is part of a long-term trend toward rising temperatures and
extreme weather events resulting from global warming.
Global average surface temperatures have increased by more than
1.4°F since the mid-19th century. In 2007, the United Nations’
Intergovernmental Panel on Climate Change concluded that the evidence
of global warming is “unequivocal” and that human activities are
responsible for most of this rise in temperature.
To examine recent temperature patterns in the United States, we
compared temperature data for the years 2000–2007 with the historical
average, or “normal,” temperature for the preceding 30 years,
1971–2000. Our data were collected at 255 weather stations—those with
the highest quality data—in all 50 states and Washington, DC. Overall,
we found that temperatures were above the 30-year average across the
country, indicating pervasive warming.
2007: 10th Warmest Year on Record for the United States
The
2007 average temperature for the continental United States was the 10th
warmest on record, according to the National Climatic Data Center.
Nearly every state in the Lower 48 experienced above normal
temperatures in 2007. Our analysis of 2007 temperature data at the
local level showed:
In 2007, the average temperature was at least 0.5°F above the
30-year average at 84 percent of the weather stations. The Mountain
West and Southeast in particular experienced warmer-than-normal average
temperatures in 2007. In Helena, Montana, the average temperature
during 2007 was 4.6°F above the 30-year average. Average temperatures
soared 4.0°F above the 30-year average in Reno, Nevada and 3.0°F or
more above normal in six cities in Tennessee.
The average maximum temperature—the peak temperature on any given
day—was at least 0.5°F above the 30-year average at 71 percent of the
weather stations. Warmer-than-average days hit the Southeast and parts
of the West the hardest in 2007, with average peak temperatures soaring
4°F or more above normal in Greenville-Spartanburg, South Carolina;
Chattanooga, Knoxville, and Nashville, Tennessee; Rapid City, South
Dakota; Helena, Montana; and Louisville, Kentucky.
Rising temperatures resulted in extremely hot days in 2007 where
temperatures peaked at or above 90°F at locations across the country.
Nearly three-fourths (71 percent) of the locations examined recorded
more frequent days with peak temperatures of at least 90°F compared
with the historical average. Raleigh, North Carolina experienced 45
more 90°F or warmer days than normal in 2007.
The average minimum temperature—the lowest temperature recorded on a
given day, usually at night—was at least 0.5°F above the 30-year
average in 2007 at 79 percent of the stations examined. Minimum
temperatures were particularly mild in the Mountain West, Midwest, and
parts of the East. The average minimum temperature soared 5.5°F above
the 30-year average in Reno, Nevada.
2000–2007: Temperatures Rising
The above-average
temperatures of 2007 are part of a warming trend across the United
States. Our analysis of local temperature data for 2000–2007 showed:
The average temperature from 2000–2007 was at least 0.5°F above the
30-year average at 89 percent of the locations studied. Average
temperatures in Alaska were the most anomalous, with Talkeetna near
Denali National Park averaging nearly 4°F above the 30-year average.
The average maximum temperature from 2000–2007 was at least 0.5°F
above the 30-year average at nearly three-fourths (74 percent) of the
locations studied. Talkeetna, Alaska also experienced the most
above-normal maximum temperature (2.9°F) over the eight-year period.
Between 2000 and 2007, the average minimum temperature was at least
0.5°F above the 30-year average at 82 percent of the locations studied.
In Reno, Nevada, the average minimum temperature was 5.3°F above normal.
The latest climate science tells us that the United States and the
world must break its dependence on fossil fuels and transition rapidly
to 100 percent clean, renewable energy if we hope to avoid the most
catastrophic effects of global warming. The United States should
immediately take the following first steps:
Adopt mandatory, science-based caps on global warming pollution. At
minimum, those caps should reduce total U.S. emissions by 20 percent
below today’s levels by 2020 and by 80 percent below today’s levels by
2050. Revenues from any program that puts a price on global warming
pollution should be used to aid in the transition to a clean energy
economy and to reduce the cost of emission reductions to consumers.
Make energy efficiency improvements and accelerated development of
renewable energy the centerpiece of our environmental and economic
development policies. Advanced building energy codes; strong energy
efficiency standards for buildings, appliances, and vehicles; and
mandatory targets for renewable power generation and energy efficiency
savings are among the policies that can reduce global warming pollution
and put the nation on a clean energy path.
Make global warming and fossil fuel dependence central
considerations in land-use planning and public sector investment
decisions. America should increase its investment in public
transportation and rail transportation to reduce emissions from
transportation. All new public buildings should meet rigorous standards
for energy efficiency and the use of clean energy.
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