November 21, 2013
The Arctic Report Card (www.arctic.noaa.gov/reportcard/) considers a wide range of environmental observations throughout the Arctic, and is updated annually. The 2013 update to the Report Card illustrates the significant effects of year-to-year and regional variability, which overlie the impacts of the persistent warming trend that began over 30 years ago. For instance, after a record-setting year in 2012, relatively cool air temperatures in summer 2013 across the central Arctic Ocean, Greenland and northern Canada facilitated an increase in the summer sea ice extent and a decrease in the extent and duration of melting at the surface of the Greenland ice sheet. In contrast, summer 2013 was one of the warmest on record in Alaska, where new record high temperatures were set at some permafrost observatories, and Fairbanks, in the center of the state, experienced a record 36 days with temperatures of 27°C or higher.
A second key point in Report Card 2013 is that the longer-term impacts of the warming climate on the physical environment are influencing the Arctic terrestrial and marine ecosystems. Evidence is seen from the foundations through the upper levels of the food web. The ability to more effectively measure, monitor, document and attribute these changes depends on a continued increase in the number of comprehensive research surveys and sustained long-term observing programs.
In early 2013, the Northern Hemisphere-wide spring snow cover extent (SCE) was lower than the observed average for the period 1967-2013. In May, a new record low SCE occurred in Eurasia and in June the North American SCE was the fourth lowest on record. These conditions were driven by rapid snow melt, rather than anomalously low snow accumulation prior to melt onset, and can be linked to the regional distribution of surface air temperature and circulation patterns. New record high permafrost temperatures at a depth of 20 meters below the surface were also set in summer 2013 at permafrost observatories on the North Slope of Alaska, in the Brooks Range, Alaska, and in the High Canadian Arctic, where measurements began in the late 1970s.
While fewer new record-setting events occurred in 2013 compared to 2012, the impacts of the persistent warming trend of over 30 years remain clearly evident. For instance, while the minimum summer extent of the Arctic sea ice cover in September 2013 exceeded the record low of 2012, it still ranked as the sixth lowest summer minimum extent since observations began in 1979, and the seven lowest ice extents since 1979 have occurred in the last seven years (2007-2013). In the upper Arctic Ocean, relatively high freshwater and heat contents continued to be observed in 2013 in the Beaufort Gyre region of the Canada Basin. Immediately adjacent to the Arctic Ocean, in regions where there are large areas of summer open water and widespread above-average sea surface temperatures, tundra vegetation greenness (a measure of productivity) and growing season length have continued to increase since observations began in 1982. Also on land, lake ice break-up in spring 2013 was earlier than average throughout much of the Arctic, and ice duration was shorter than average in many regions. In Greenland, further extensive melting occurred at the surface of the ice sheet, where the maximum melt extent and average melt extent were at or above the average over the 30-year period of record.
The response of the physical environment system to the persistent warming temperatures is having an impact on the marine ecosystem. Responses of Arctic benthic communities to climate and anthropogenic factors are being observed as shifts in species distribution patterns and in the appearance of new (to the Arctic) species. Some of the changes in the characteristics of the Arctic benthic and community structure are likely related to recent changes in food supplied via primary production, which can be linked to the rapid and dramatic loss of the sea ice cover. New fish species have also been reported in several areas, especially the Canadian Beaufort Sea, which likely represents both altered distributions resulting from climate change and previously occurring but undetected species.
As with the marine environment, the assessment of climate change impacts on arctic wildlife is complicated because these land-based communities respond to a host of other factors, including disease, hunting rates and changes to management regimes. Consequently, studies of large land mammals convey a mixed message. Regional surveys of muskoxen indicate that their numbers have mostly stabilized or increased since the 1970s, following strategic introductions and conservation efforts. In contrast, many caribou and reindeer herds are currently at relatively low numbers. Recovery of these herds is difficult to predict, given the cyclic nature of the abundance of these herds and their complex interactions in a warming climate.
The Arctic Report Card is supported by the Arctic Research Program in the NOAA Climate Program Office. The preparation of Arctic Report Card 2013 was directed by a U.S. inter-agency editorial team of representatives from NOAA, the Cold Regions Research and Engineering Laboratory and the U.S. Arctic Research Commission. The 18 essays in Report Card 2013, representing the collective effort of an international team of 147 researchers in 14 countries, are based on published and ongoing scientific research. Independent, peer-review of the scientific content of the Report Card was facilitated by the Arctic Monitoring and Assessment (AMAP) Program of the Arctic Council. The Circumpolar Biodiversity Monitoring Program (CBMP), the cornerstone program of the Conservation of Arctic Flora and Fauna (CAFF) Working Group of the Arctic Council, provides leadership on the ecosystem elements of the Report Card.