The report State of the Climate surveys the changing state and the behavior of the physical climate system. The 22nd annual issue reported that in 2011
• For the first time, globally averaged carbon dioxide concentrations in the atmosphere surpassed 390 parts per million
• Globally averaged heat stored in the top 2,300 feet of the oceans was the highest since records began in 1993.
• According to four different data sets, global surface temperatures continue to rise, increasing at a rate of about 0.31ºF per decade since 1980.
• Because of La Niña, global surface temperatures were cooler than the record highs of 2010, but were above the past-30-year average
• Oceans were saltier in areas that were already drier and fresher in areas already rainy, indicating an increase in the global water cycle
• Average temperature in the Arctic has increased by about 3.6ºF since the mid‐1960s, more than 2 times faster than at lower latitudes
• Record high temperatures were recorded at 20 meters below the surface at all permafrost observatories on Alaska’s North Slope
• Sea ice extent in September was the second least since the satellite era began
• Ice four years old or more was 81% below average, a record low
• Above‐average air temperatures and declining albedo (reflectivity) caused extreme melting and mass loss of the Greenland ice sheet
• Sea surface temperatures in five of the Arctic seas were the second warmest in on record
• Since 1982, tundra greenness has increased by 15.5% in the North American Arctic and by 8.2% in the Eurasian Arctic
The report reaches these conclusions:
• Long-term trends
- Temperatures at the Earth’s surface and lower atmosphere continue to warm, while the stratosphere continues to cool
- The climate indicators expected to increase in a warming world are continuing to increase and those expected to decrease are continuing to decrease
• Although cooler than in 2010, the annual global temperature was nonetheless one of the 15 warmest years on record. The Arctic continues to warm faster than the rest of the globe.
• La Niña contributed to many, but not all, of the year’s numerous extreme weather and climate events.
The report was written by 378 authors from 48 countries and issued as a special supplement to the Bulletin of the American Meteorological Society.