Increased Arctic Temperatures and Diminishing Sea Ice Cover

This post switches back to the Arctic and is based on a recent video on the BBC about the sea ice extent in 2015. The video explains that 2015 had the fourth lowest ice cover since records began. NASA satellites have calculated that 300 billion tonnes of ice is being lost from the Greenland ice cap every year, mainly due to the fact that the Polar Regions (Greenland and Antarctica) are warming faster than any location on the planet.

Figure 1: This map shows that over the last decade compared with 20/50 years ago the Arctic region has warmed by up to 5 degrees centigrade, more than anywhere else on Earth (source). Melting ice can have implications for wildlife that relies on sea ice to hunt such as polar bears and the albedo effect of ice which reflects solar energy back into space. The albedo effect was mentioned in an earlier post (see post 3).

The National Snow & Ice Data Centre gave a 2015 summary review concerning the melt of 2015. The summer months of 2015 revealed a high pressure static over Greenland which lasted several weeks. This gave a temperature contrast to different regions of Greenland; the north of the island was warmer than usual by up to 2⁰C which accelerated ice melt while the central and south eastern regions experienced a cooling of 1⁰C which decreased the ice melt. Thule in northwest Greenland experienced a 4⁰C rise in July due to southerly winds bringing in warm air. Maslanik et al’s 2007 paper on a younger thinner Arctic ice cover agrees with these findings that as years go by, the Arctic sea ice is becoming younger and consequently thinner as it has less time to form. Their study found that 58% of the ice was between 2 and 3 years old compared to 35% in the 1980s, a reduced percentage because most of the ice was older. It also found that in 2007, the sea ice extent had decreased by 42% compared to the 1980s. At the time in 2007, Maslanik et al speculated that the decreased ice cover could become the norm. As the ice cover in 2012 shows, which was the lowest ice cover ever recorded, Maslanik could be correct that a smaller ice extent will continue as years go on.

Global warming with increased Arctic temperatures is therefore almost certainly the cause of this decreased ice cover. Despite the reduced short term temperatures in central Greenland, the overall trend illustrates an increase in Arctic temperatures.