WASHINGTON — A new analysis of NASA temperature data collected from more than 1,000 weather stations around the globe, from satellites monitoring ocean temperatures and from Antarctic research stations shows that 2000 to 2009 was the warmest decade on record.
The analysis, from NASA's Goddard Institute for Space Studies in New York, also showed that 2009 was virtually tied with five other years — 1998, 2002, 2003, 2006 and 2007 — as the second warmest year on record for global average surface temperature. In the Southern Hemisphere, it was the warmest year on record.
The global temperatures were high even though North America had some cool periods, particularly the unseasonably cold weather in December.
"The contiguous 48 states cover only 1.5 percent of the world area, so the United States' temperature does not affect the global temperature much," James Hansen, the institute's director, said in a statement Thursday about the new analysis."
The NASA space studies institute has reported that since 1880, when good record keeping began, the average global temperature has increased by about 1.5 degrees Fahrenheit. The increase over each of the past three decades has been about one-third of a degree Fahrenheit.
Hansen noted that there's substantial year-to-year variability in global temperatures caused by El Nino and La Nina, periodic climate patterns in the tropical Pacific Ocean. "When we average temperature over five or 10 years to minimize that variability, we find global warming is continuing unabated."
Climate scientists say that heat-trapping gases, mainly from the use of fossil fuels, are the dominant reason for the temperature increase. Blogs that deny climate change or claim it isn't a serious problem for the future challenge NASA's temperature-gathering methods and analysis.
The data that the space studies institute uses are publicly available on its Web site, along with charts, animations and videos about global temperatures.
The Met Office Hadley Center in the United Kingdom also studies global temperatures. Unlike NASA, it omits large areas of the Arctic and Antarctic. NASA said in a news release Thursday: "Although the two methods produce slightly differing results in the annual rankings, the decadal trends in the two records are essentially identical."
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Watch a video and animation from NASA in Quick Time about global temperatures
Background about NASA's temperature record collection and links to the datasets