365 Days of Climate Awareness 103 – State of the Climate 2011

 

Continuing with the joint annual AMS/NOAA worldwide climate report, 2011, while above the 1981-2010 surface temperature average, was not among the very warmest. The year began and ended in La Niña phases, which correlates with rainfall in Australia and cooler-than-usual temperatures across the northern Pacific. Air temperatures across North America, northern Europe and northern Asia featured several hot spells.

Despite the  La Niña events, sea surface temperatures globally were above average, but hurricane activity, outside of the North Atlantic, was not. Rain and snowfall were above average in the southern hemisphere, while droughts occurred throughout the northern. In November, a large cyclone moved north into the Bering Sea between Alaska and Russia,bringing with it a massive pulse of warm water and winds which broke up a large swath of sea ice nearly two months into the ice-gain season.

Top: Ocean heat content change, to 700 m, from 1993 to 2010. Bottom: with 95% confidence scale applied (color intensity displays statistical significance).  

The oceans continued their trend of becoming saltier in evaporative regions (such as the eastern Mediterranean and northern Indian Ocean and Red Sea), and fresher in rainy regions such as the northern Pacific. This indicates that the rate of the global water cycle is increasing. Though tropical sea surface temperatures were cooler than usual, in both north and south mid latitudes, the sea surface was significantly warmer than average.

Arctic annual max/min sea ice extents, 1978-2011.

The record of ocean heat content, measured via satellite and drift buoys down to roughly 700 m, is not nearly as complete as air and sea surface measures. For that reason only longer-term trends across portions of the entire ocean can be identified with much confidence. Cooling occurred primarily in the eastern Pacific and southwestern Atlantic, with warming trends, very strong especially in the northern Atlantic and western Pacific, happening nearly everywhere else.

Arctic sea ice cover continued its progressive disappearance, with both the annual maximum in March and the September minimum below the longer-term trend. Ice melt in Antarctica increased, happening over a larger area, mostly along the coasts, with little melting in the interior. Sea ice extent began the year at roughly an average level.A great deal of sea ice was lost in the southern Indian Ocean area,but was largely balanced by ice gain in the southern Pacific, both thought to be due to ocean current activity.

Tomorrow: introduction to climate indicators. (Because, it’s becoming clear: these year-by-year accounts will mean much more if I describe some of the major indicators discussed in the reports. Vivent les détours!)

Be brave, and be well.