The past decade was the warmest ever on record, showing that global warming is "continuing unabated," according to a new report from NASA.

New surface temperature figures released by the US space agency on Thursday show average global temperatures have increased by 0.2°C (0.36°F) per decade throughout the past three decades.

According to NASA, 2005 was the warmest year on record since modern temperature measurements began in 1880. NASA's study indicates that despite 2008 being the coolest year of the decade, 2009 shares the title for second-warmest year ever, along with 1998, 2002, 2003, 2006, and 2007. (Apparently global warming has more #2's than Al Qaeda).

But the agency warns not to hold yearly temperatures as terribly important in the greater scheme of tracking a global warming trend.

"There's substantial year-to-year variability of global temperature caused by the tropical El Niño-La Niña cycle," commented the outspoken thermageddon prophet James Hansen, director of NASA's Goddard Institute for Space Studies, in a statement. "But when we average temperature over five or ten years to minimize that variability, we find that global warming is continuing unabated."

NASA said the figures show a "clear warming trend" on record, though there was a "leveling off" between the 1940s and 1970s. In total, average global temperatures have increased by about 0.8°C (1.5°F) since 1880, it claims.

"That's the important number to keep in mind," stated Gavin Schmidt, a GISS climatologist. "In contrast, the difference between, say, the second and sixth warmest years is trivial since the known uncertainty — or noise — in the temperature measurements is larger than some of the differences between the warmest years."

The increased temperature in 2009 came despite an unusually nippy December in North America. According to NASA, high air pressures from the Arctic decreased the east-west flow of the jet stream while increasing the north to south flow from the Arctic, causing cool air to flood down across the continent.

"Of course, the contiguous 48 states cover only 1.5 per cent of the world area, so the U.S. temperature does not affect the global temperature much," said Hansen.

Unlike the UK Met Office Hadley Centre's measurements, NASA said it uses only publicly available data for its sources. The data comes from over a thousand meteorological stations around the world, satellite observations of sea surface temperature, and Antarctic research station measurements, the space agency said. It also provides information on how to repeat its analysis for armchair climatologists and skeptics playing along at home. ®