Test your reasoning.
IF
(A) Glaciers on Earth are retreating due to global warming,
AND IF
(B) The glacier on Mount Kilimanjaro is retreating,
THEN
(C) The retreat of the Kilimanjaro glacier is due to global warming.
TRUE OR FALSE?
The answer, viewed a test of deductive reasoning, is neither. We have insufficient information.
Statement (A) does not say that all glaciers on Earth are retreating. The fact is that some are not retreating.
However, the vast majority are retreating, and most glaciologists attribute the retreat of most glaciers to global warming. Still, it is reasonable to assume that some glaciers may be retreating due to other factors.
If we want to know the cause of the retreat of the Kilimanjaro glacier, we can’t rely on A+B–>C logic (especially flawed A+B–>C logic). We need to study the glacier itself.
That’s what glaciologists Philip W. Mote and Georg Kaser did, as described in the feature article in the July-August 2007 issue of American Scientist, “The Shrinking Glaciers of Kilimanjaro: Can Global Warming Be Blamed?”. (Readers should note an extensive bibliography in the peer-reviewed scientific literature.)
Their conclusion: Don’t blame global warming for this one. As the magazine’s sub-headline notes, “The Kibo ice cap, a ‘poster child’ of global climate change, is being starved of snowfall and depleted by solar radiation.”
The key sentences in the article itself read:
“But the commonly heard–and generally correct–statement that glaciers are disappearing because of warming glosses over the physical processes responsible for their disappearance. Indeed, warming fails spectacularly to explain the behavior of the glaciers and plateau ice on Africa’s Kilimanjaro massif, just 3 degrees south of the equator, and to a lesser extent other tropical glaciers.”
This article serves as a beacon that should be heeded by both those who argue for political action based on the scientific consensus and those who assert that the scientific consensus is the result of a scientific process that has been corrupted by politics.
For the former, the message is stick to the powerful evidence for global warming (and its anthropogenic cause). Don’t look for a politically “sexy” symbol. The consensus stands powerfully on its own, without the need for a “poster child.”
In An Inconvenient Truth, Al Gore’s narration accompanies a series of photographs documenting the retreat of glaciers all over the world. Almost all of those have been scientifically tied to global warming. Unfortunately, Kilimanjaro, the one chosen as an icon for political reasons, appears to be in retreat for other reasons. That gives ammunition to the other side of the political argument.
If the scientific argument hinged on Kilimanjaro as strongly as the political one does, then the consensus view would be in trouble. The article does not dispute the consensus (“generally correct–statement that glaciers are disappearing because of warming”). It just tells people to be careful in the way portray the issue politically.
But the skeptics need to be equally careful about claiming Kilimanjaro as the poster child for a flawed scientific process. This article, and the peer-reviewed research on which it rests, are powerful examples that an ongoing, robust scientific dialogue continues on all aspects of this important question.
Overstatements by politicians and the media about the end of the debate (rather than the continued strengthening of the consensus) do science and scientists a terrible disservice.
I am proud to be a member of Sigma Xi, the Scientific Research Society, which publishes American Scientist as a way of sharing current research issues of public importance with the educated public. It has a long history of non-partisanship and the promotion of public service.
I know that some people will throw out accusations of Sigma Xi’s bias here, and others will argue that global warming is responsible for the current climate that is starving the Kilimanjaro glacier. To both sides I say, show me the evidence.
(If you got this far, you might want to discover my archive of book reviews on this topic at the The Science Shelf).
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