Climate change is happening and its almost certainly man made, that's the conclusion of the latest IPCC report on global warming.
But the report also looked at where climate change is happening now and few places, the authors concluded, are being as dramatically affected as the Arctic.
“The report presents a robust picture of a progressively warming world," said Dr Tim Jones from the Met Office Handley Centre.
See also
What did we learn from the IPCC report
"Reducing Arctic sea ice extent, melting ice sheets and glaciers, rising sea level, ocean acidification, and large-scale hydrological cycle changes under the influence of anthropogenic [man made] emissions of greenhouse gases."
Few deny that the Arctic sea ice has been shrinking for some time (see chart) but the report suggested this was both part of a long-term trend, and largely caused by man-made climate change.
Between 1979 and 2012 "Annual mean Arctic sea ice extent decreased... with a rate that was very likely in the range 3.5 to 4.1% per decade."
The summer ice decreased even more - between 9.4% and 13.6% in each decade according to the study which adds "Anthropogenic influences have very likely contributed to Arctic sea ice loss since 1979."
“The rate of loss of Arctic sea Ice, melting of mountain glaciers and the Greenland Ice sheet are unprecedented," said Professor Bob Watson, Tyndall Centre for Climate Change Research and the University of East Anglia.
In the future the authors warned the melting will continue.
"It is very likely that the Arctic sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises," said the study.
Indeed, the report authors warn, if climate change policies are not implemented and emissions continue to rise as forecast in their 'worse case' scenario (RCP 8.5) then the Arctic Ocean could be nearly ice free in September within forty years (a prediction made with a medium level of confidence).
The reduction in late-summer sea ice in the Arctic appears to be unprecedented over the last 1500 years - Professor Bamber.
The authors noted that a projection for when the arctic may be nearly ice free in the 21st century cannot be made with confidence for the other scenarios.
And the impact goes beyond the Arctic.
“The evidence of persistent and continued changes to all frozen parts of the planet is clearer than ever, " said Prof Jonathan Bamber, Director of the Bristol Glaciology Centre at the University of Bristol.
"Glaciers around the world have been declining over at least the last 5 decades, mass loss from the great ice sheets covering Antarctica and Greenland has been increasing over the last two decades and the reduction in late-summer sea ice in the Arctic appears to be unprecedented over the last 1500 years."
IPCC links
Headline statements from the summary for policymakers
