The current New Scientist reports news from the Planet Under Pressure conference in London that a British climate scientist has determined that the "disappearance of Arctic sea ice has crossed a 'tipping point' that could soon make ice-free summers a regular feature across most of the Arctic Ocean."
"Tim Lenton at the University of Exeter has carried out a day-by-day assessment of Arctic ice-cover data collected since satellite observation began in 1979" and "presented his hotly anticipated findings for the first time" indicating that Arctic sea ice never recovered from its extreme low in 2007.
Lenton said, "The system has passed a tipping point."
Before the brutal summer of 2007 set a new record for ice melt in the Arctic, "sea ice systematically fluctuated between extensive cover in winter and lower cover in summer." While scientific climate models predicted the ice would recover each winter, that has not happened. In fact, Lenton reported, "the difference between winter and summer ice cover has been a million square kilometres greater than it was before."
What this means is that the Arctic sea ice has been permanently altered in the last few years and likely will not recover for centuries or longer. It is not clear why but it is possible that so much heat was absorbed in the exposed ocean in 2007 that "the thicker multiyear ice, which used to persist through the summer, was melted."
Another possibility is that "the loss of ice may have changed air circulation patterns above the Arctic in ways that have similarly 'locked in' the change."
Last November, "Prof Peter Wadhams, of Cambridge University, said the ice that forms over the Arctic sea is shrinking so rapidly that it could vanish altogether in as little as four years' time."
Another scientist at the Planet Under Pressure conference warned that the Arctic warming could trigger dangerous methane-releasing tsunamis. Euan Nisbet of Royal Holloway, University of London, said "warming ocean currents east of Greenland were melting ice in the seabed" which could "trigger landslides on steep submarine slopes in the area, unleashing tsunamis capable of hitting the UK, and releasing buried methane that could amplify global warming."
The last time something like this happened was 8000 years ago off the coast of Norway. "It is thought that landslides in Norway - the Storegga Slides - triggered one of the biggest tsunamis ever recorded on Earth when a landlocked sea in the Norwegian trench burst its banks" and transformed the Britain peninsula into "an island nation."
Meanwhile, the Arctic Methane Emergency Group (AMEG) lists 2007 as the year atmospheric methane re-emerged as a global warming threat after leveling off in 2000. Scientists "think the increased emissions are from the surface of the planet," the result of "a carbon feedback due to global warming." AMEG said we should recognize this as "a planetary emergency because of the recognized potential of an abrupt increase in atmospheric methane leading to abrupt global warming."
Scientists report "as much as 50 million metric tons of methane is released per year" now in the Arctic as rapid melting continues.
The most catastrophically dangerous methane source is Arctic sea floor methane hydrate. This is frozen solid methane gas under pressure in sea floor sediments. The largest source of Arctic methane hydrate is the East Siberian Arctic shelf (ESAS) , the largest continental shelf in the world. Methane is now venting to the atmosphere from under the shelf. All the evidence indicates that an abrupt massive release of methane gas from Arctic hydrates could happen which most likely would be catastrophe to the global climate and our planet."
"It is certain if the Arctic is not cooled these Arctic methane sources will greatly
increase with global warming and that will greatly increase the rate of global
warming. Unstoppable runaway Arctic warming will lead to unstoppable
runaway global warming. To prevent runaway Arctic warming the Arctic must be
Since the "Arctic contains several times the amount of carbon in the atmosphere," it will be game over for all of us if we are foolish enough to allow its release.