We are seeing the first signs of dangerous climate change in the Arctic. This is our warning that humanity is facing a dire future.
The Arctic region is fast approaching a series of “tipping points” that could trigger an abrupt domino effect of large-scale climate change across the entire planet. The region contains arguably the greatest concentration of potential tipping elements.
If set in motion, these can generate profound alterations which will place the Arctic not at the periphery, but at the core of the Earth system. There is evidence that these chain reactions have begun. This has major consequences not just for “nature”, but for the future of humankind as the changes progress.
Research shows that the Arctic is now warming at three times the global average. The loss of Arctic summer sea-ice forecast over the next four decades - if not before - is expected to have abrupt knock-on effects in northern mid-latitudes, including Beijing, Tokyo, London, Moscow, Berlin and New York. The loss of sea ice - which melted faster in summer than predicted - is linked tentatively to recent extreme cold winters in Europe.
Arctic records show unambiguously that sea ice volume has declined dramatically over the past two decades. In the next 10 years, summer sea ice could be largely confined to north of coastal Greenland and Ellesmere Island, and is likely to disappear entirely by mid-century.
Some environmental and biological elements, including weakening of the oceanic biological carbon pump and the thermohaline circulation,melting of the Greenland ice cap, thawing of Arctic permafrost and methane hydrate deposit, the decline of forest and peat fires in the boreal region, may be linked in a domino effect of tipping points that cascade rapidly once this summer sea ice is lost.
Despite this danger, 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.
And of course there are those who benefit from a warmer Arctic. A drop in Arctic ice has 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 has 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 is being discussed. Not everyone is in favour of reducing the impact of warming on Arctic ice.
But all of us need to take this melting seriously. Top predators such as polar bears are declining. More methane gas is entering the atmosphere as permafrosts and submarine methane hydrates thaw. Freshwater discharge has increased 30% in recent years. And the Arctic Sea is warming faster as the ice cap melts, trapping more solar heat instead of reflecting it back into space, since ice reflects about 90% of the indecent solar radiation compared to the absorption of 60% of solar radiation by an open ocean surface devoid of ice.
In the subarctic region, dieback of the boreal forest and desiccation of peat deposits is leading to uncontrolled peat fires (such as those that plagued Russia in the summer of 2010) increases with warmer weather. This burning will further enhance greenhouse gas emissions.
We expect the Arctic will switch from being a carbon dioxide sink to become instead a source of greenhouse gases if seawater temperatures rise 4-5°C.
The rate of Arctic climate change is now faster than ecosystems and traditional Arctic societies can adapt to. Tipping points do not have to be points of no return. Several tipping points, such as the loss of summer sea ice and melting of permafrost, may be reversible in principle - although hard in practice.
However, should these changes involve the extinction of 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.
The Arctic crisis is a test of our capacity as scientists, and as societies, to respond to abrupt climate change. We need to stop debating the existence of tipping points in the Arctic and start managing their dangerous reality.