Temperature changes 2000-2009 relative to the 1951-1980 mean. Warmer areas in red, cooler blue. The largest increases occurred in the Arctic and part of the Antarctic. Image courtesy NASA. Click to Enlarge
Temperature changes 2000-2009 relative to the 1951-1980 mean. Warmer areas in red, cooler blue. The largest increases occurred in the Arctic and part of the Antarctic. Image courtesy NASA. Click to Enlarge.
The decade 2000-2009 was the warmest since modern recordkeeping began, and 2009 was tied for the second warmest single year, a new analysis of global surface temperature shows. The analysis, conducted each year by the NASA Goddard Institute for Space Studies (GISS), an affiliate of the Earth Institute, also shows that in half the world--the Southern Hemisphere--2009 was the warmest year yet recorded.
"There's always an interest in the annual temperature numbers and on a given year's ranking, but usually that misses the point," said James Hansen, the director of GISS, which conducts a similar analysis each year. "There's substantial year-to-year variability of global temperature. But when we average temperature over five or ten years to minimize that variability, we find that global warming is continuing unabated."
2008 was the coolest year of the decade, due to strong cooling of the tropical Pacific Ocean, but 2009 saw a return to near-record global temperatures. The past year’s temperatures were only barely surpassed by 2005, the warmest recorded year, and tied with a cluster of others — 1998, 2002, 2003, 2006 and 2007 — as second warmest. Through the last three decades, the GISS surface temperature record shows an upward trend of about 0.2°C (0.36°F) per decade. The greatest increases in 2000-2009 came in the Arctic and part of Antarctica. Except for a leveling off between the 1940s and 1970s, Earth’s surface temperatures have increased steadily since 1880, when modern scientific instrumentation became available to monitor temperatures precisely. In total, average global temperatures have increased by about 0.8°C (1.5°F) since 1880.
At least in the United States, the near-record temperature of 2009 would seem to be all the more striking