Global Warming Reports
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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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