The future of human kind faces dire consequences due to arguably the first signs of dangerous climate change in the Arctic, says a leading international scientist from The University of Western Australia.
The Director of UWA's Oceans Institute, Winthrop Professor Carlos Duarte, says the Arctic region is fast approaching a series of imminent "tipping points" that could trigger an abrupt domino effect of large-scale climate change across the entire planet.
As lead author in a paper published in the Royal Swedish Academy of Sciences' journal AMBIO and in a parallel commentary in Nature Climate Change, Professor Duarte said the Arctic region contained arguably the greatest concentration of potential tipping elements for global climate change.
"If set in motion, they can generate profound climate change which places the Arctic not at the periphery but at the core of the Earth system," Professor Duarte said. "There is evidence that these forces are starting to be set in motion."
"This has major consequences for the future of human kind as climate change progresses."
Professor Duarte said the loss of Arctic summer sea ice forecast over the next four decades - if not before - was expected to have abrupt knock-on effects in northern mid-latitudes, including Beijing, Tokyo, London, Moscow, Berlin and New York.
Research showed that the Arctic was warming at three times the global average and the loss of sea ice - which had melted faster in summer than predicted - was linked tentatively to recent extreme cold winters in Europe.
Professor Duarte - winner of last year's prestigious Prix d'Excellence awarded by the International Council for the Exploration of the Sea - said the most dangerous aspect of Arctic climate change was the risk of passing critical "tipping points".
Arctic records showed unambiguously that sea ice volume had declined dramatically over the past two decades, Professor Duarte said. In the next 10 years, summer sea ice could be largely confined to north of coastal Greenland and Ellesmere Island, and was likely to disappear entirely by mid-century.
"Some environmental and biological elements may be linked in a domino effect of tipping points that cascade rapidly once the summer sea ice is lost," Professor Duarte said.
However, semantic confusion masquerading as scientific debate - although providing excellent media fodder - had delayed an urgent need to start managing the reality of dangerous climate change in the Arctic, Professor Duarte said.
A drop in Arctic ice had opened new shipping routes, expanded oil, gas and mineral exploitation, increased military and research use, and led to new harbours, houses, roads, airports, power stations and other support facilities
It had triggered a new gold rush to access these resources, with recent struggles by China, Brazil and India to join the Arctic Council where the split of these resources was being discussed.
But increased deposits of black carbon (soot) from coal-burning power stations and stoves on snow and ice had accelerated warming and ice melt.
Top predators such as polar bears were declining, more methane gas was entering the atmosphere as permafrosts and submarine methane hydrates thawed, freshwater discharge had increase 30 per cent recent years and the Arctic Sea was warming faster as the ice cap melted, trapping more solar heat instead of reflecting it back into space.
In the subarctic region, dieback of the boreal forest and desiccation of peat deposits leading to uncontrolled peat fires (such as those that affected Russia in the summer of 2010) would further enhance greenhouse gas emissions.
Professor Duarte said the rate of Arctic climate change was now faster than ecosystems and traditional Arctic societies could adapt to.
The Arctic was expected to stop being a carbon dioxide sink and become a source of greenhouse gases if seawater temperatures rose 4-5ºC.
"It represents a test of our capacity as scientists, and as societies to respond to abrupt climate change," Professor Duarte said.
"We need to stop debating the existence of tipping points in the Arctic and start managing the reality of dangerous climate change.
"We argue that tipping points do not have to be points of no return.
"Several tipping points, such as the loss of summer sea ice, may be reversible in principle - although hard in practice.
"However, should these changes involve extinction of key species - such as polar bears, walruses, ice-dependent seals and more than 1000 species of ice algae - the changes could represent a point of no return.
"Confusion distracts attention from the urgent need to focus on developing early warning indicators of abrupt climate change, address its human causes and rebuild resilience in climate, ecosystems and communities."