Global Warming Meltdown?
John L. Daly
In July 1997, GreenPeace released their trumpeted report on the Arctic, and media stations worldwide publicised TV video footage of an Alaskan glacier in apparently serious trouble, with images of rapidly melting ice, icebergs falling into the sea, and all blamed (of course) on global warming.
As often in such matters, GreenPeace omit to tell the full story.
The Bering Glacier is located on the south coast of Alaska, facing the North Pacific Ocean and is described as the world's "largest surging glacier". That is, it periodically surges forward at very rapid rates (for a glacier), travelling in May 1995 some 750 metres in only 2 weeks. With such rapid surges, the ice mass flows into low warmer altitudes where the inevitable end result is an equally rapid melting of the ice front. Several years later, after the glacier front has receded, another surge takes place and the cycle is repeated all over again.
Of course, if one witnesses only the melt-back phase of the cycle, it makes for dramatic TV footage, easily fooling the less discriminating media outlets.
While some of the more sedate slow-moving glaciers may provide some clues as to past and present climate change, a periodically `surging' glacier like the Bering Glacier makes assessment of past climate change very problematic.
It would be analogous to measuring mean sea level on a Hawaiian surfing beach !
If the Bering or any other glacier was being affected by past or present climate change, it could only change in response to the local climate, not global climate directly. Global climate change may well impact on local climates, but it is the local climates which the glaciers must respond to, since it is these which condition the temperatures and precipitation locally which cause the glacier to either expand or retreat.
This is where GreenPeace in their hurry to `prove' global warming impacting on the Arctic neglected to mention what the local temperatures nearest the Bering Glacier were doing, to back up their claims that the Bering Glacier was being eroded by human-induced `global warming'.
We can now correct that little oversight for them.
There are three weather stations in the same general region as the Bering Glacier. These are Cordova, 100 km to the west, Yakutak, 200 km to the east, both on the Pacific coast either side of the glacier mass, and the third is Northway, 300 km inland to the north. (Source is Alaska Climate Research Center, all rights reserved)
|As we can see, Cordova shows a fairly neutral trend since 1945, but was significantly warmer in the 1920s and 1930s. There is nothing in this record to suggest any significant or recent climate warming. It is also the closest record to the Bering Glacier itself.|
|Yakutat also shows a largely neutral trend overall, although there are greater variations present, such as the cold period in the late 1960s and early 1970s and the warm `spike' in 1980/81. But overall, there is nothing here to support the idea that there has been regional warming sufficient to affect glacier growth or retreat. Rather, changes in glacier patterns are most likely to be the result of precipitation rather than temperature changes.|
|Northway lies 300 km inland with data from 1942. It also shows a largely neutral trend. Unlike the other two which are close to the ocean, Northway gives an indication of inland temperatures, uninfluenced by the ocean. But even here, there is no trend worth noting.|
Worldwide, more stable glaciers do generally show some retreat. This is invariably blamed on global warming, even though it is widely accepted that many such glaciers have been in continuous retreat since the Little Ice Age of the late 17th century. But even when glaciers advance (such as Norway's Eventyrisen Glacier and New Zealand's Franz Josef Glacier a few years ago), that too is blamed on global warming! When there is but a single agenda, any change, whether too much wind, too little rain, heat waves, freezes, droughts, floods, etc. all get blamed on global warming regardless whether the causal mechanism involved makes any sense or not.
Glacier retreat this century is consistent with some global warming, but this in turn is consistent with the greater solar activity in the latter half of this century and with the `rebound' of global temperatures from the Little Ice Age. The fact that many glaciers still advance, and that the Bering Glacier made two major surges in the 1990s suggest that the background global warming is very small this century, probably at the low end of the IPCC `consensus' estimate, namely +0.3 deg. C.
That said, the GreenPeace videos of the Bering Glacier made for great TV drama, even if it was hopelessly bad science.
John L. Daly
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