An international team of scientists estimate that up to half of the recent global warming in Greenland is caused by natural climate variations.
The research, published in the journal Nature, sheds new light on the rapid melting of Greenland’s glaciers. Crucially it indicates that global warming caused by carbon dioxide emissions may not be the only factor responsible.
Dr Ailie Gallant from Monash University said these natural variations stem from an unusually warm tropical Pacific Ocean, east of Papua New Guinea. This “sweet spot” is partly responsible for Arctic warming.
“A lot of the time, major climate changes are attributed to global warming caused by carbon emissions. But we can’t forget that natural climate variations can also have a significant part to play.
“Carbon dioxide emissions remain the key cause of global warming. But if we can learn more about how and why natural climate variations occur, we can better understand what we might expect from future climate changes and put plans in place to minimise or potentially reduce impacts,” Dr Gallant said.
The team focused on the Arctic region, which has warmed more rapidly than the Earth as a whole. Greenland and parts of eastern Canada have experienced some of the most extreme warming since 1979, at a rate of 1 degree Celsius per decade – twice the global average.
Examining atmospheric temperature and pressure data from 1979 to 2012, the scientists discovered evidence that natural climate variations are impacting on this area of the Arctic at the same time as human-induced climate change.
Professor David Battisti from the University of Washington said that the data indicates that roughly half of the recent warming in Greenland is due to natural climate variations. The other half is caused by carbon emissions from humans.
“Nothing we have found challenges the idea that globally, glaciers are retreating. We looked at this place because the warming there is really remarkable. Our findings help us to understand on a regional scale how much of what you see is human induced by the build up of CO2 and how much of it is natural variability,” Professor Battisti said.