The Arctic-Antarctic seesawby Jonathan DuHamel on Sep. 24, 2012, under Climate change
Shouldn’t global warming be global? Much has been made in the media about the “record” sea ice melt in the Arctic this summer. Typical is the headline in the Arizona Daily Star: “Arctic ice shrinks to all-time low; global warming cited as the cause.” There are two problems with that headline, which I will get to below. Meanwhile, it is little mentioned in the press that Antarctic continental ice is growing and sea ice has reached record or near record maximums extent. If global warming is the cause of “record” Arctic sea ice melt, why is the Antarctic sea ice reaching record or near record maximums? Should not global warming temper Antarctic sea ice formation? The graphs below show the Arctic and Antarctic sea ice extent as of September 20, 2012.
As for the headline “Arctic ice shrinks to all time low….”, it’s an all time low if you start counting in 1979, the modern satellite era. But, as I’ve shown in another post, Ice Follies and Hiding the Decline, a 1990 report from the IPCC records earlier data which show that in 1974 Arctic sea ice melt was as great or greater than it is this year.
As for the headline “Global warming cited as cause” we see that when the Arctic reaches a minimum sea ice extent, the Antarctic reaches a maximum extent. There is a seesaw effect. That is shown most dramatically this year and in 2007 when the Arctic reached the previous “record” low, and the Antarctic sea ice reached a “record” maximum high extent.
Doug Hoffman discusses this seesaw effect at Resilient Earth. This oscillation seems to be related to natural, solar driven variations.
The basic difference between the Arctic and Antarctic is that the Arctic is mainly ocean surrounded by land, and the Antarctic is land surrounded by ocean. The Arctic is therefore more subject to solar-driven oscillations such as the Arctic Oscillation and Pacific Decadal Oscillation which are responsible for changes in ocean currents that can drive ice south toward warmer water or create warmer currents in the Arctic ocean. That, coupled with storms, have a significant effect on Arctic sea ice. As I reported in the post referenced below: the National Snow & Ice Data Center said of this year’s Arctic melt: “Sea ice extent dropped rapidly between August 4 and August 8. While this drop coincided with an intense storm over the central Arctic Ocean, it is unclear if the storm prompted the rapid ice loss.” NSIDC called the storm “The Great Arctic Cyclone of 2012″ and noted the storm caused “mechanical break up of the ice and increased melting by strong winds and wave action during the storm.” Nothing to do with global warming.
Meanwhile, both continental and sea ice are increasing in Antarctica. “Satellite radar altimetry measurements indicate that the East Antarctic ice sheet interior north of 81.6-S increased in mass by 45±7 billion metric tons per year from 1992 to 2003.” (Source) And a new paper says in part: “Antarctic Peninsula ice core records indicate significant accumulation increase since 1855…” (Source). According to NASA’s Earth Observatory, total Antarctic sea ice has increased by about 1% per decade since the start of the satellite record..
It seems that Arctic and Antarctic sea ice extent can be explained by natural cycles. Those invoking “global warming” must explain why warming causes Antarctic ice to increase and Arctic ice to decrease.
As for the low sea ice in the Arctic this year, it has happened before:
Reports from fishermen, seal hunters and explorers, …, 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. -Washington Post, November 2, 1922.
“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 of ice with which the Greenland Seas between the latitudes of 74̊ and 80̊N 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.
Perhaps Mark Twain was right when he said: “If you don’t read the newspaper you are uninformed, if you do read the newspaper you are misinformed.”
UPDATE: NASA now admits that the storm caused most of the melt: “This year, a powerful cyclone formed off the coast of Alaska and moved on Aug. 5 to the center of the Arctic Ocean, where it churned the weakened ice cover for several days. The storm cut off a large section of sea ice north of the Chukchi Sea and pushed it south to warmer waters that made it melt entirely. It also broke vast extensions of ice into smaller pieces more likely to melt.” See statement and video animation here.
Paul Homewood’s article on Arctic vs Antarctic temperatures