It is an article of faith among global warming alarmists that continued warming will precipitate a tipping point at which all the Arctic sea ice will melt and usher in even more warming. Typical of this is a 2007 ABC news story: North Pole Could Be Ice Free in 2008,
The rationale behind this view is that ice reflects sunlight back into space providing a cooling effect. But if enough ice melts, the darker ocean water will absorb the heat of the sun and accelerate warming. This sounds logical, but:
Researchers at The Centre for Geogenetics at the University of Copenhagen found “that there have been large fluctuations in the amount of summer sea ice during the last 10,000 years.”
They also state:
“During the so-called Holocene Climate Optimum, from approximately 8000 to 5000 years ago, when the temperatures were somewhat warmer than today, there was significantly less sea ice in the Arctic Ocean, probably less than 50% of the summer 2007 coverage, which is absolutely lowest on record.”
“Our studies show that there are great natural variations in the amount of Arctic sea ice. The bad news is that there is a clear connection between temperature and the amount of sea ice. And there is no doubt that continued global warming will lead to a reduction in the amount of summer sea ice in the Arctic Ocean. The good news is that even with a reduction to less than 50% of the current amount of sea ice the ice will not reach a point of no return: a level where the ice no longer can regenerate itself even if the climate was to return to cooler temperatures. Finally, our studies show that the changes to a large degree are caused by the effect that temperature has on the prevailing wind systems. This has not been sufficiently taken into account when forecasting the imminent disappearance of the ice, as often portrayed in the media.” (Source)
And yes, the polar bears survived the much reduced ice level.
The Danish study builds on previous research such as a 1996 study which also found large fluctuations in the amount of Arctic sea ice.
And there have been other reports of disappearance of Arctic ice:
“A considerable change of climate inexplicable at present to us must have taken place in the Circumpolar Regions, by which the severity of the cold that has for centuries past enclosed the seas in the high northern latitudes in an impenetrable barrier of ice has been, during the last two years, greatly abated.”
“2000 square leagues [approximately 14,000 square miles or 36,000 square kilometers] of ice with which the Greenland Seas between the latitudes of 74 and 80 N have been hitherto covered, has in the last two years entirely disappeared.” (Royal Society, London. Nov. 20, 1817. Minutes of Council, Vol. 8. pp.149-153)
Or this story:
Arctic Ocean Getting Warm; Seals Vanish And Icebergs Melt
The Arctic ocean is warming up, icebergs are growing scarcer and in some places the seals are finding the waters too hot, according to a report to the Commerce Department yesterday from Consul Ifft, at Bergen, Norway .
Reports from fishermen, seal hunters and explorers, he declared, all point to a radical change in climatic conditions and hitherto unheard-of temperatures in the Arctic zone. Exploration expeditions report that scarcely any ice has been met with as far north as 81 degrees 29 minutes. Soundings to a depth of 3,100 meters showed the gulf stream still very warm.
Great masses of ice have been replaced by moraines of earth and stones, the report continued, while at many points well known glaciers have entirely disappeared. Very few seals and no white fish are being found in the eastern Arctic, while vast shoals of herring and smelts, which have never before ventured so far north, are being encountered in the old seal fishing grounds.
This is from an AP story which appeared in the Washington Post, November 2, 1922.
The chart below, from The IARC-JAXA Information System (IJIS) satellite data shows the current extent of Arctic sea ice and the seasonal variation.
For comparison, the chart below from The Cryosphere Today satellite data shows Antarctic sea ice extent. Notice the seasonal maxima and minima are little changed in spite of increasing atmospheric carbon dioxide.
It seems that the Arctic tipping point is just another scary story designed to alarm the populace and justify government action. But think, if Arctic ice were to be much reduced, it would be a boon to transportation and energy exploration.
UPDATE: Model shows polar ice caps can recover from warmer climate-induced melting
A growing body of recent research indicates that, in Earth’s warming climate, there is no “tipping point,” or threshold warm temperature, beyond which polar sea ice cannot recover if temperatures come back down. New University of Washington research indicates that even if Earth warmed enough to melt all polar sea ice, the ice could recover if the planet cooled again.
Read the rest here.