Arctic report card reports persistent warming trend
The National Oceanic and Atmospheric Administration released the 2016 Arctic Report Card on December 13. The report gives an overall summary of vital Arctic statistics from the period of October 2015 through September 2016. Observations throughout this period showed a continuing trend of Arctic warming, including increased temperatures and thawing permafrost and an overall loss of Arctic sea ice.
One of the highlights from the report states that the average annual surface air temperature for the Arctic, or land north of 60° N latitude, was the highest on record since observations began in 1900, with an overall increase of 3.5° Celsius since the beginning of the twentieth century.
The increase in Arctic surface air temperature is occurring at more than twice the rate of the global increase in surface air temperature. According to the report, this increased rate is referred to as “Arctic Amplification.” The reasons for Arctic Amplification are varied, although the 2016 increases in surface air temperature can mainly be attributed to a supply of warm air originating from mid-latitude regions.
During the winter period, January to March, extremely warm temperature anomalies occurred Arctic-wide, greatly exceeding many previous records. The report states, “several locations showed January anomalies exceeding +8 degrees Celsius.”
According to the Arctic report card, “Arctic air temperature is an indicator of regional and global climate change… the magnitude and Arctic-wide character of the long-term temperature increase is a major indicator of global warming and the influence of increases in Greenhouse gases.”
The overall warming of the Arctic region is causing permafrost to thaw, which exposes large quantities of organic soil carbon to decompose. The permafrost carbon is made up of hundreds to thousands of years of plants, animals and microbes that are accumulated into the frozen soil.
According to the report, “Release of just a fraction of this frozen carbon pool, as the greenhouse gases carbon dioxide and methane, into the atmosphere would dramatically increase the rate of future global climate warming.”
Arctic sea ice extent has been measured by satellite imagery since 1979. September is usually recognized as the month showing the minimum ice extent for the year, while March usually shows the maximum sea ice extent.
The Arctic report card states that the National Snow and Ice Data Center estimated the sea ice cover reached its minimum point on September 10, 2016 with 1.6 million square miles. This ties year 2007 as the second lowest minimum sea ice extent on record.
Although there is year-to-year variability, sea ice has experienced decreasing trends throughout all months and nearly all regions of the Arctic since the start of the record. In 2016, four million square miles of sea ice were lost between March and September. Before the year 2007, loss of over 3.9 million square miles was unusual, but since 2007, seven out of ten years have had this large of a loss.
The Arctic report card also highlighted the age of sea ice, as the Arctic sea ice pack is now comprised of mainly newer, thinner ice. In the 1980’s, the ice pack was made of older, thicker ice and more resilient to melting.
Also highlighted by the 2016 report were the effects of Arctic warming on small species, such as Arctic shrews. Shrews and their parasites, according to the report, “serve as indicators for present and historical environmental variability.” New parasites indicate northward shifts of these sub-Arctic species, which also increases Arctic biodiversity.