The 2010 meteorological year, which ended on 30 November, was the warmest in NASA's 130-year record, data posted by the agency today shows. Over the oceans as well as on land, the average global temperature for the 12-month period that began last December was 14.65˚C. That's 0.65˚C warmer than the average global temperature between 1951 and 1980, a period scientists use as a basis for comparison.
The 2010 meteorological year was slightly warmer than the previous warmest year, the 2005 calendar year, when the average temperature was 14.53˚C.
In 2010, temperatures measured over land alone were also the warmest ever, with instruments showing a December-November average of 14.85˚C. Combining this warming with above-average ocean temperatures led to the global average of 14.65˚C.
November brought frigid temperatures to certain areas of Europe. But the data, compiled by the NASA Goddard Institute for Space Studies in New York City, show that, globally, last month was the warmest November ever recorded, nearly 0.96˚C warmer than the 1951 to 1980 average for the month.
According to NASA climatologist and Goddard director James Hansen, the main driver for the increased warmth was the Arctic, where temperatures in Hudson Bay were "10˚C above normal" for November. That month, Hansen says, "sea ice was absent while normally that [body of water] is covered by sea ice." Water devoid of ice absorbs much more solar radiation than water covered with ice, which reflects much of the radiation back toward space.
The record temperatures occurred despite a moderate occurrence of La Niña, a phenomenon over the Pacific Ocean that tends to lead to cooler temperatures at the surface, affecting the global mean.