SCIENCE: The Earth climbs to new heights on heat charts -- NOAA (07/29/2010)
Lauren Morello, E&E reporter
The last decade was the warmest since modern weather record-keeping began in the 1880s, according to a new report from the National Oceanic and Atmospheric Administration.
Furthermore, each year between 2000 and 2009 was hotter than average conditions in the 1990s, which were in turn hotter than average conditions in the 1980s, said co-editor Deke Arndt, chief of the climate monitoring branch of NOAA's National Climatic Data Center.
He led a team of 303 researchers from 48 countries that compiled the agency's 20th annual "State of the Climate" report, which Arndt likened to a medical checkup -- this time, for a planet instead of a person.
The report evaluates 10 aspects of Earth's climate that it says are "clearly and directly related to surface temperatures, [and] all tell the same story: global warming is undeniable."
Those indicators include warming surface air and sea temperatures, rising seas, declining sea ice, and shrinking ice and snow cover on land.
Some of the biggest changes occurred at the poles. The area covered by Arctic sea ice reached a new record summer low three times in the last decade.
Dramatic shrinkage of Arctic ice since 1979
The total area covered by sea ice at the end of each summer was roughly equal to that of the lower 48 United States when satellite monitoring of the Arctic began in 1979, said Walt Meier of the National Snow and Ice Data Center.
"Today, when we reach the [summer] minimum, the typical area is equivalent to states west of the Mississippi, sometimes considerably less than that," he said.
Down south, the Antarctic Peninsula is warming five times faster than the global average, the report says, and "significant ice loss" has been observed along the peninsula and Antarctica's western coast.
Climate graphs
Rising CO2 levels in the atmosphere (middle chart) are driving Arctic Sea ice areas down and the planet's temperatures up. Photo courtesy of National Oceanic and Atmospheric Administration.
"What this data is doing is screaming that the world is warming," said Peter Thorne, a senior researcher at the Cooperative Institute for Climate and Satellites.
Thorne said the fact that so many disparate aspects of the climate system indicated warming showed such conclusions "can't be driven by a single individual or even several small groups -- the evidence is there to see."
Small changes with glacier-sized impacts
Overall, the 2000s were 0.96 degree Fahrenheit hotter than the 20th-century average, the report says. And what seems like a small change in global average temperature can produce noticeable climate effects.
The observed temperature rise of about 1 degree Fahrenheit during the past half-century has "already altered the planet," the report says, citing melting of glaciers and sea ice, more intense rains and more common -- and hotter -- heat waves.
"People have spent thousands of years building society for one climate and now a new one is being created," the analysis said. "One that's warmer and more extreme."
Still, the report only evaluates the state of the climate and does assign a cause for the observed warming, said Tom Karl, the transitional director of NOAA's climate service.
"This report does not speak to trying to make the link between the cause and what we observed," he said, "but this is the basis for that next step."
The NOAA report will be published as a special edition of the Bulletin of the American Meteorological Society.
