State of the Climate 2012: Warmish
Late last week, the American Meteorological Society released its “State of the Climate” report for 2012, which provides a comprehensive, peer-reviewed look at, well, the state of the world’s climate. In what was no surprise to anyone but the most hardened science-denier, 2012 was one of the 10 warmest years on record.
According to new NOAA Administrator and former astronaut Kathryn Sullivan, “Many of the events that made 2012 such an interesting year are part of the long-term trends we see in a changing and varying climate—carbon levels are climbing, sea levels are rising, Arctic sea ice is melting, and our planet as a whole is becoming a warmer place.”
According to the report, some of the more dramatic evidence of a warming world can be found in the northern latitudes.
Conditions in the Arctic were a major story of 2012, with the region experiencing unprecedented change and breaking several records. Sea ice shrink to its smallest “summer minimum” extent since satellite records began 34 years ago. In addition, more than 97 percent of the Greenland ice sheet showed some form of melt during the summer, four times greater than the 1981–2010 average melt extent.
The report tracks dozens of climate indicators, using thousands of measurements, from multiple sets of independent data. The report is published annually and the 2012 report is the 23rd edition. Some highlights:
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.
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.
The temperature of permafrost, or permanently frozen land, reached record-high values in northernmost Alaska. A new melt extent record occurred July 11–12 on the Greenland ice sheet when 97 percent of the ice sheet showed some form of melt, four times greater than the average melt this time of year.
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.
Ocean heat content remains near record levels: Heat content in the upper 2,300 feet, or a little less than one-half mile, of the ocean remained near record high levels in 2012. Overall increases from 2011 to 2012 occurred between depths of 2,300 to 6,600 feet and even in the deep ocean.
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.
Not everything was hotter. Tropical cyclones were about average, temperatures in the lower stratosphere (six to ten miles above the Earth’s surface), and Antarctic sea ice expanded.
Unfortunately, charts and graphs alone won’t solve the problem. Expect more of the same in next year’s report.