State of the Climate in 2012 Report Released
The American Meteorological Society (AMS) released their State of the Climate in 2012 report earlier this month. The peer-reviewed report uses climate indicators to track and identify changes and overall trends to the global climate system. Some indicators include greenhouse gas concentrations, cloud cover, sea surface temperature, sea-level rise, and snow cover. Scientists from National Oceanic and Atmospheric Association (NOAA)’s National Climatic Data Center serve as lead editors.
The data collected indicated that 2012 was one of the 10 warmest years on record, but the major story was conditions in the Arctic. The region experienced unprecedented change and broke several records including a record breaking sea ice shrinkage and more than 97% of the ice sheet in Greenland showing some form of melting.
Other highlights include:
- Warm temperature trends continue near Earth’s surface: Four major independent datasets show 2012 was among the 10 warmest years on record, ranking either 8th or 9th, depending upon the dataset used. The United States and Argentina had their warmest year on record.
- La Niña dissipates into neutral conditions: A weak La Niña dissipated during spring 2012 and, for the first time in several years, neither El Niño nor La Niña, which can dominate regional weather and climate conditions around the globe, prevailed for the majority of the year.
- The Arctic continues to warm; sea ice extent reaches record low: The Arctic continued to warm at about twice the rate compared with lower latitudes. Minimum Arctic sea ice extent in September and Northern Hemisphere snow cover extent in June each reached new record lows. Arctic sea ice minimum extent (1.32 million square miles, September 16) was the lowest of the satellite era. This is 18 percent lower than the previous record low extent of 1.61 million square miles that occurred in 2007 and 54 percent lower than the record high minimum ice extent of 2.90 million square miles that occurred in 1980.
- Sea surface temperatures increase: Four independent datasets indicate that the globally averaged sea surface temperature for 2012 was among the 11 warmest on record. After a 30-year period from 1970 to 1999 of rising global sea surface temperatures, the period 2000–2012 exhibited little trend. Part of this difference is linked to the prevalence of La Niña-like conditions during the 21st century, which typically lead to lower global sea surface temperatures.
- Sea level reaches record high: Following sharp decreases in global sea level in the first half of 2011 that were linked to the effects of La Niña, sea levels rebounded to reach record highs in 2012. Globally, sea level has been increasing at an average rate of 3.2 ± 0.4 mm per year over the past two decades.
- Greenhouse gases climb: Major greenhouse gas concentrations, including carbon dioxide, methane, and nitrous oxide, continued to rise during 2012. Following a slight decline in manmade emissions associated with the global economic downturn, global CO2 emissions from fossil fuel combustion and cement production reached a record high in 2011 of 9.5 ± 0.5 petagrams (1,000,000,000,000,000 grams) of carbon, and a new record of 9.7 ± 0.5 petagrams of carbon is estimated for 2012. Atmospheric CO2 concentrations increased by 2.1 ppm in 2012, reaching a global average of 392.6 ppm for the year. In spring 2012, for the first time, the atmospheric CO2 concentration exceeded 400 ppm at several Arctic observational sites.