People around the world can agree on one thing: 2011 was a year of wild weather, from severe heat to historic droughts to fierce cyclones. Yet a new study from the National Oceanic Atmospheric Administration (NOAA) shows that 2011 was the coolest year on record since 2008, even though temperatures
The peer-reviewed report—the 2001 State of the Climate—was issued in coordination with the American Meteorological Society (AMS). It includes data from 378 scientists from 48 countries globally collected by environmental monitoring stations and instruments on land, sea, sky and ice. The report used 43 climate indicators to track changes and trends to the global climate system, including greenhouse gases, temperatures, cloud cover, sea surface temperature, ocean salinity, sea-level rise, sea ice and snow cover.
Two years of La Niña conditions, cooler-than-average waters in parts of the Pacific,affected regional climates and contributed to many significant weather events during 2011. Scientists generally conclude that the research shows that many of these weather extremes are consistent with a warming planet. Other extreme weather events that occurred last year include the worst flooding in Thailand in almost a century, drought and tornadoes in the U.S., deadly floods in Brazil, and the most intense heat wave in central and southern Europe since 2003.
Highlights from the report include:
- The Arctic is warming at twice the rate as compared with lower latitudes, and the South Pole station recorded its highest temperature ever of 9.9 Fº on December 25th, breaking the previous record by more than two degrees.
- Greenhouse gasses including carbon dioxide, methane and nitrous oxide continued to rise steadily.
- The amount of Arctic sea ice was not only below average for 2011, but has been since June 2001.
- Temperatures were higher in the tropical stratosphere while they dropped in thepolar stratosphere during the early winter of 2011, leading to lower than usual ozone levels in the Arctic.
- Both the global sea surface temperature and ocean heat content rose to record heights despite La Niña conditions.
- Following a trend that began in 2004, oceans were saltier in the western and central tropical Pacific but fresher than average in areas of high precipitation, demonstrating that rainfall may be increasing in already rainy areas, and evaporation is getting worse in drier areas.
A complementary article by the AMS and NOAA, entitled Explaining Extreme Events of 2001 from a Climate Perspective, was also published. The report examines the links between climate change and weather events in 2011.