
How much sunlight Earth reflects naturally varies a lot. The bigger the range of natural variability, the greater the odds that any evidence of a manmade effort to brighten up the planet would be lost in the “background noise.”
How much sunlight Earth reflects naturally varies a lot. The bigger the range of natural variability, the greater the odds that any evidence of a manmade effort to brighten up the planet would be lost in the “background noise.”
February 18, 2014
Most of the Arctic boundary waters were warmer than average in summer 2013, but a few cool pockets appeared in the western Arctic and the Greenland Sea. Warmer waters are drawing new species from lower latitudes into the Arctic.
In March 1988, thick, multi-year ice comprised 26 percent of the Arctic's ice pack. In 2005, that number dropped to 19 percent. In 2013, it dropped to 7 percent.
Averaged over September 2013, sea ice extent was 2.07 million square miles—larger than last year's record low, but still more than 17 percent below average and the sixth smallest September extent on record.
To be consistent with NOAA's use of 30-year periods for the official "climate normals," the National Snow and Ice Data Center switched its baseline period for sea ice analyses from 1979-2000 to 1981-2010. Compared to the new normal, the low ice conditions of the recent past will appear less abnormal than they used to.
September 17, 2013
August 22, 2013
The extent of snow-covered ground in the Northern Hemisphere at the end of the cold season (June) hit a record low. Annual average snow cover extent has not exceeded the long-term average even once since 2003. Between 1979 and 2011, the snow cover in June is declining even faster than the end-of-summer Arctic sea ice extent.
Glacier mass balance in 2011 (the most recent year for which worldwide analysis is complete) was negative, and preliminary data indicate that 2012 will probably be the 22nd consecutive year of net losses in glacier mass. Between 1980 and 2011, glaciers around the world lost the water equivalent of 15.7 meters. That would be like slicing a roughly 17-meter-thick slab off the top of the average glacier and repeating that exercise worldwide.