By Renee Schoof
WASHINGTON — The year 2008 was the ninth warmest year since instrumental temperature measurements began in 1880, and all of the nine warmest years have occurred in the past 11 years, NASA reported on Tuesday.
The new data from NASA's Goddard Institute for Space Studies and other government agencies on Tuesday adds to the evidence scientists have been observing about a warming Earth as fossil fuel burning emits heat-trapping gases into the atmosphere.
NASA also reported that the January to November global temperature was 0.76 degrees Fahrenheit above the average for the 20th Century.
NASA also noted that the past year was cooler than any since 2000. Scientists note that global warming is a steady trend, but within it there are natural variations.
The NASA report noted that "Eurasia, the Arctic and the Antarctic Peninsula were exceptionally warm, while much of the Pacific Ocean was cooler than the long-term average." It said the relatively cooler temperature in the tropical Pacific was due to a La Nina, the cool phase of a natural temperature variation.
Britain's Met Office on Tuesday also said that La Nina was part of the reason 2008 was slightly cooler than earlier years this decade. By Britain's accounting, 2008 was the 10th warmest year on record dating back to 1850, and all 10 of the warmest years occurred since 1997.
"Human influence, particularly emission of greenhouse gases, has greatly increased the chance of having such warm years," said Peter Stott of the Met Office in a statement Tuesday.
The Met Office also reported that global temperatures from 2000 to 2008 are nearly 0.36 degrees Fahrenheit higher than the average for 1990 to 1999.
The National Oceanic and Atmospheric Administration on Tuesday summarized these and other trends, including:
- The 2008 Atlantic hurricane season was the third costliest, after 2005 and 2004.
- The U.S. had nearly 1,700 tornadoes from January through November, which ranks second behind 2004 for the most tornadoes in a year since records began in 1953.
- Arctic sea ice in 2008 reached its second lowest level at the end of the melting season in September, following a record low in 2007. In 2008, the ice shrank to 1.74 million square miles, which was 0.86 million square miles below the average annual minimum from 1979 to 2000.
Sea ice loss is important because ice reflects most of the sun's radiation, but open ocean water absorbs most of it, adding to the warming trend both in the ocean and on land.