Though not as extreme as last year, new report by NOAA and partners finds that the Arctic continues to show evidence of a shift to a new warmer, greener state
- Air temperatures: While Eurasia had spring air temperatures as much as 7 °F above normal, central Alaska experienced its coldest April since 1924 with birch and aspen trees budding the latest (26 May) since observations began in 1972. Summer across a broad swath of the Arctic was cooler than the previous six summers, when there had been pronounced retreat of sea ice. But Fairbanks, just below the Arctic Circle in Alaska, experienced a record 36 days with temperatures at or exceeding 80 °F.
- Snow cover: The snow extent in May and June across the Northern Hemisphere (when snow is mainly located over the Arctic) was below average in 2013. The North American snow cover during this period was the fourth lowest on record. A new record low was reached in May over Eurasia.
- Sea ice: Despite a relatively cool summer over the Arctic Ocean, the extent of sea ice in September 2013 was the sixth lowest since observations began in 1979. The seven lowest recorded sea ice extents have occurred in the last seven years.
- Ocean temperature and salinity: Sea surface temperatures in August were as much as 7 °F higher than the long-term average of 1982-2006 in the Barents and Kara Seas, which can be attributed to an early retreat of sea ice cover and increased solar heating. Twenty-five percent more heat and freshwater is stored in the Beaufort Gyre, a clockwise ocean current circulating north of Alaska and Canada, since the 1970s.
- Greenland ice sheet: During a summer when air temperatures were near the long-term average, melting occurred across as much as 44% of the surface of the Greenland ice sheet, close to the long-term average but much smaller than the record 97% in 2012.
- Vegetation: The Arctic is greening as vegetation responds to warmer conditions and a longer growing season. Since observations began in 1982, Arctic-wide tundra vegetation productivity (greenness) has increased, with the growing season length increasing by 9 days each decade.
- Wildlife: Large land mammal populations continued trends seen over the last several decades. Muskox numbers have increased since the 1970s, in part due to conservation and introduction efforts, while caribou and reindeer herds continue to have unusually low numbers.
- Marine fishes: The long-term warming trend, including the loss of sea ice and warming of waters, is believed to be contributing to the northward migration into the Arctic of some fish such as Atlantic mackerel, Atlantic cod, capelin, eelpout, sculpin and salmonids.
- Black carbon: While black carbon (soot) originating from outside the Arctic has decreased by 55% since the early 1990s, primarily due to economic collapse in the former Soviet Union, increasing numbers of wildfires fueled by greater amounts of vegetation in a warmer, drier climate, have the potential to increase atmospheric black carbon in the high latitudes.
Sea surface temperatures in August 2013 compared to the 1982-2006 average and sea ice extent (areas with 15% or more ice cover, solid white). Arctic boundary waters warmer than average in summer 2013; the Arctic Ocean and adjacent waters are becoming more hospitable to species from lower latitudes. Map by NOAA Climate.gov, based on data provided by Wendy Ermold and Mike Steele, University of Washington. Download here / Full gallery (Credit: NOAA)
Maximum melt extent on the Greenland Ice Sheet on July 26, 2013 (left), and July 11, 2012 (right), the summer peaks for each respective year. Melt area was 44% at the peak melt in 2013, compared to 97% in 2012. The surface melt on the ice sheet is back near average for 2013. Maps by NOAA Climate.gov, based on data provided by Thomas Mote, University of Georgia. Download here / Full gallery (Credit:NOAA)
The winter ranges of many reindeer and caribou herds are smaller than they used to be and many populations have unusually low numbers. This map depicts the annual range of 24 migratory reindeer and caribou herds and their population status. Map by NOAA Climate.gov, based on data provided by Don Russell and Kim Poole, CARMA project. Download here / Full gallery (Credit: NOAA)