Washington — The year 2010 ranked as one of the two warmest years on record, according to an assessment compiled by almost 370 scientists in 45 countries. The National Oceanic and Atmospheric Administration (NOAA) released 2010 State of the Climate, an annual report, on June 27.
The findings present “multiple indicators, same bottom line conclusion,” according to a NOAA briefing paper. “Consistent and unmistakable signal from the top of the atmosphere to the bottom of the oceans: The world continues to warm.”
Compiled by NOAA with the American Meteorological Society, the report tracks 41 different climate indicators, including temperatures (both lower and upper atmospheres), precipitation, greenhouse gases, humidity, sea ice and glaciers.
“We’re continuing to closely track these indicators,” said Thomas R. Karl, director of NOAA’s National Climatic Data Center, “because it is quite clear that the climate of the past cannot be assumed to represent the climate of the future.”
Air temperature was the second-warmest on record, the data show, with the Arctic warming at about twice the rate of the lower latitudes.
Two of the planet’s major climate patterns created conditions for extreme weather events in various places in 2010. The year began with the warm El Niño pattern in the Pacific Ocean, but transitioned to its “cool sister,” La Niña, by July, which created below-normal cyclone activity in the Pacific basin without the ocean heat, which drives the fierce, spinning winds. But La Niña did send record spring rains to Australia, the most severe storms recorded there in more than a century.
The Arctic Oscillation entered what is known as its “negative phase” in 2010. This means that cold Arctic air pushed its way farther south than normal, and as a result some North American cities added new pages to the record books keeping track of their snow and ice. Farther south, cities accustomed to mild winters also saw unusual cold. The same weather pattern gave Britain its coldest winter in more than 30 years and arctic conditions to other parts of Europe.
The 2010 weather conditions also led to Arctic melting, which reduced sea ice at the northernmost point of the world to an unusually low level. Glacial melt in Greenland shrank ice sheets at a rate not seen since 1958, and Alpine glaciers shrank for the 20th consecutive year.
But Antarctica was a different story, with the average sea ice volume reaching a record maximum, as the result of a pattern of unusual atmospheric variability called the Antarctic Oscillation, which kept cold air in the south.