When the industrial revolution began in the early 18th century humans started to poor CO2 into the atmosphere. First from burning coal, later from oil and gas. Since then this anthropogenic climate change has led to a global warming of about 1°C. Unfortunately, warming of the Arctic turn out to be 2-3 times faster than the global average, and in November temperatures in parts of the Arctic rose to 20°C (36°F) above normal. In the not too distant future scientists predict the Arctic Ocean will be largely sea ice free in the summer. Observations also show that the Greenland ice sheet is melting and raises sea levels.
Sea ice extent declining rapidly
Arctic sea ice normally varies throughout the year from covering an area of 15,000 Km2 (1.5 times Canada) in March to 6000 Km2 in September. In recent years, however, the ice cover in September has almost been halved compared with normal. The picture shows the ice in September 2012 compared to normal observed by NASA. With the current the Arctic Ocean might be ice free in summer before the middle of this century.
Albedo is the fraction of solar energy reflected from the Earth back into space. While ice and snow reflect 85% of the energy, land and water absorb 85%. Due to the reduced albedo, the Arctic is currently about to transform itself from a thermal shield to an accelerator of global warming (positive feedback).
Data available for everyone
The figure below shows the status 8. December 2016, by far the lowest on record for this time of the year.
Credit: National Snow and Ice Data Centre
Sea ice volume declining faster than the extent
The sea ice is normally 1-4 meters thick and the volume has been even more reduced than the area compared with normal over the last decades. Since 1979, the minimum volume shrank by 80%
Even difficult to pinpoint a date, with the current trend, the Arctic Ocean might be ice free in summer before the middle of this century. The Greenland ice sheet is also melting. Greenland ice covers an area three times the size of Texas and is at the top more than three kilometers thick. The rapid warming of the Arctic is also leading to the melting of the Greenland ice sheet. In recent years in average 270 Gt has been melting per year. In comparison, this would be enough to fill 110 million Olympic swimming pools with water. As melting seems to accelerate, projections for sea level rise must be altered accordingly. The newest climate models project that by 2100, Greenland’s ice sheet could contribute 4 to 9 cm sea level rise. If the global warming continues there is a risk of passing the so called a “tipping point” where melting cannot be stopped. Melting of the entire Greenland ice sheet will provide a global sea level rise of 7,4 meters. The image (NASA) shows melting ice on Greenland in July 2012. On July 12, 97% of the ice surface was melting
Cosequences of the ice melting
The melting ice in the Arctic will have a number of consequences. Global climate change will accelerate and sea level will increase. Freshwater runoff into the ocean might also change ocean circulations. New shipping routes might be unlocked and more fossil fuel reserves exposed. Major impact will occur on ecosystems. Arctic Indigenous peoples’ livelihoods might disappear, and a third of the world’s polar bears might disappear within 40 years, according to a new study.