2015 Arctic Ice and Snow Cover Lowest in the Satellite Record
On March 19, the National Snow & Ice Data Center reported this years Arctic sea ice, reached on February 25, 2015, is likely reached likely reached its maximum extent for the year on February 25th, measuring 14.54 million square kilometers (5.61 million square miles). 2015’s maximum ice extent was the lowest in the satellite record, with below-average ice conditions everywhere except in the Labrador Sea and Davis Strait. The maximum extent is 1.10 million square kilometers (425,000 square miles) below the 1981 to 2010 average of 15.64 million square kilometers (6.04 million square miles) and 130,000 square kilometers (50,200 square miles) below the previous lowest maximum that occurred in 2011.
This year’s maximum occurred 15 days earlier than the 1981 to 2010 average date of March 12.
Over the first two weeks of March, temperatures throughout the eastern Arctic at approximately 3,000 feet altitude were several degrees Celsius above average, with temperatures as much as 8 to 10 degrees Celsius (14 to 18 degrees Fahrenheit) above average in the Barents Sea between Svalbard and Franz Josef Land.
Melt extent in Greenland was also well above average in 2014, tying for the 7th highest extent in the 35-year satellite record. Overall, climate patterns favored intense west coast and northwest ice sheet melting, with relatively cool conditions in the southeast. Relative to the 35 years of continuous satellite measurements, 2014 is tied with 2006 for seventh highest, and is well above the 1981 to 2010 average. Melt area total (the sum of daily melt extents for the entire June through August period) was approximately 100,000 square kilometers (38,600 square miles) above the 1981 to 2010 average. The top eight melt extent years have all occurred since 2002.
Greenland’s snow and ice was significantly darker in the summer of 2014 than in 2013, and similar to 2011. This darkening trend is apparent in the comparison of the past 15 years of average summer (June through August), during which Greenland’s snow and ice has been getting dirtier and the geographic extent of the darker Arctic Ocean water (darker than snow and ice) has been growing substantially. This has reduced the ice and snow “albedo” effect. The warmer temperatures in the Arctic have caused more of the Arctic’s ice and snow cover to melt, which has reduced the Arctic’s overall albedo, thus more of the Sun’s energy is absorbed by the earth, rather than reflecting the Sun’s rays back out to space, which causes even more warming, et cetera. This is what scientists call a “positive feedback” climate process.
The darker snow on Greenland is a result of increased soot, dust, and even microbes in the snow, and the general trend of warmer summer conditions. Snow also darkens over time as jagged snowflakes evolve into rounder snow crystals. The larger snow grain size allows more light to be absorbed by the snow.