The Arctic experienced record air temperatures and a new low in peak ice extent during 2015, with scientists warning that climate change is having “profound effects” on the entire marine ecosystem and the indigenous communities that rely upon it.
The latest report card on the state of the Arctic from National Oceanic and Atmospheric Administration (Noaa), a US Department of Commerce scientific agency, revealed the annual average air temperature was 1.3 degrees above the long-term average – the highest since modern records began in 1900. In some parts of the frigid expanse, the temperature exceeded 3 degrees above the average, taken from 1981 to 2010.
This record heat has been accompanied by diminishing ice. The Arctic Ocean reached its peak ice cover on February 25th – a full 15 days earlier than the long-term average and the lowest extent recorded since records began in 1979. The minimum ice cover, which occurred on September 11th, was the fourth smallest in area on record.
More than 50 per cent of Greenland’s huge ice sheet experienced melting in 2015, with 22 of the 45 widest and fastest-flowing glaciers shrinking in comparison to their 2014 extent.
Not only is the amount of ice decreasing, it is becoming younger – Noaa’s analysis of satellite data shows that 70 per cent of the ice pack in March was composed of first-year ice, with just 3 per cent of the ice older than four years. This means the amount of new, thinner ice has doubled since the 1980s and is more vulnerable to melting.
The report card – compiled by 72 scientists from 11 countries – noted sharp variations in conditions in the northern part of the Arctic compared to its southern portion. The melting season was 30-40 days longer than the long-term average in the north but slightly below average in the south, suggesting that changes to the jet stream, causing colder air to whip across the southern part of the Arctic, are having an impact.
Noaa said warming in the Arctic is occurring at twice the rate of anywhere else in the world –a 2.9 degree average increase over the past century – and that it is certain climate change, driven by the release of greenhouse gases, is the cause.
"There is a close association between air temperature and the amount of sea ice we see, so if we reduce the temperature globally it looks like it will stabilise the Arctic," said Dr James Overland, an oceanographer.
“The next generation may see an ice-free summer but hopefully their decedents will see more ice layering later on in the century.”
Dr Overland said if the world hits the 2 degrees warming limit agreed by nations in the recent Paris climate talks, the Arctic will experience anything from a 4 degree to 5 degree increase in temperature by 2050. The Chukchi Sea, by Alaska, is warming the fastest of any of the Arctic waters while the overall minimum ice extent has slumped by 13.4 per cent a decade, on average.
– (Guardian service)