Date: January 22nd 2010

Jan 21, 2010

Steve Cole Headquarters, Washington
202-358-0918 stephen e cole@nasa gov

Leslie McCarthy Goddard Institute for Space Studies, New York 212-678-5507 leslie m mccarthy@nasa gov

RELEASE: 10-017

NASA RESEARCH FINDS LAST DECADE WAS WARMEST ON RECORD, 2009 ONE OF WARMEST YEARS

WASHINGTON -- A new analysis of global surface temperatures by NASA scientists finds the past year was tied for the second warmest since 1880 In the Southern Hemisphere, 2009 was the warmest year on record

Although 2008 was the coolest year of the decade because of a strong La Nina that cooled the tropical Pacific Ocean, 2009 saw a return to a near-record global temperatures as the La Nina diminished, according to the new analysis by NASA's Goddard Institute for Space Studies (GISS) in New York The past year was a small fraction of a degree cooler than 2005, the warmest on record, putting 2009 in a virtual tie with a cluster of other years --1998, 2002, 2003, 2006, and 2007 -- for the second warmest on record

"There's always interest in the annual temperature numbers and a given year's ranking, but the ranking often misses the point," said James Hansen, GISS director "There's substantial year-to-year variability of global temperature caused by the tropical El Nino-La Nina cycle When we average temperature over five or ten years to minimize that variability, we find global warming is continuing unabated "

January 2000 to December 2009 was the warmest decade on record Looking back to 1880, when modern scientific instrumentation became available to monitor temperatures precisely, a clear warming trend is present, although there was a leveling off between the 1940s and 1970s

In the past three decades, the GISS surface temperature record shows an upward trend of about 0 36 degrees F (0 2 degrees C) per decade In total, average global temperatures have increased by about 1 5 degrees F (0 8 degrees C) since 1880

"That's the important number to keep in mind," said GISS climatologist Gavin Schmidt "The difference between the second and sixth warmest years is trivial because the known uncertainty in the temperature measurement is larger than some of the differences between the warmest years "

The near-record global temperatures of 2009 occurred despite an unseasonably cool December in much of North America High air pressures from the Arctic decreased the east-west flow of the jet stream, while increasing its tendency to blow from north to south The result was an unusual effect that caused frigid air from the Arctic to rush into North America and warmer mid-latitude air to shift toward the north This left North America cooler than normal, while the Arctic was warmer than normal

"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," Hansen said

GISS uses publicly available data from three sources to conduct its temperature analysis The sources are weather data from more than a thousand meteorological stations around the world, satellite observations of sea surface temperatures, and Antarctic research station measurements

Other research groups also track global temperature trends but use different analysis techniques The Met Office Hadley Centre in the United Kingdom uses similar input measurements as GISS, for example, but it omits large areas of the Arctic and Antarctic where monitoring stations are sparse

Although the two methods produce slightly differing results in the annual rankings, the decadal trends in the two records are essentially identical

"There's a contradiction between the results shown here and popular perceptions about climate trends," Hansen said "In the last decade, global warming has not stopped "

For more information about GISS's surface temperature record, visit:

http://data giss nasa gov/gistemp/

For video and still images about this story, visit:

http://svs gsfc nasa gov/goto?010557

For more information about NASA and agency programs, visit:

http://www nasa gov

-end-

To subscribe to the list, send a message to: hqnews-subscribe@mediaservices nasa gov To remove your address from the list, send a message to: hqnews-unsubscribe@mediaservices nasa gov

The following information is a reminder of your current mailing list subscription:

You are subscribed to the following list: [list_name]

using the following email: example@example.com

You may automatically unsubscribe from this list at any time by visiting the following URL:

http://www aus-city com/cgi-bin/dada/mail cgi/u/NASA_REPORTS/

If the above URL is inoperable, make sure that you have copied the entire address Some mail readers will wrap a long URL and thus break this automatic unsubscribe mechanism

You may also change your subscription by visiting this list's main screen:

<[program_url]/list/[list]>

If you're still having trouble, please contact the list owner at: