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 ofAmerican 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.”
InAn 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 publishesAmerican 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).
(See P.S. about the logic)
I’m delighted that Andy Revkin dropped in with a link to his article about the Kilimanjaro question (Mike take note) from 2004 in the very mainstreamNew York Times.
I can see I’m wearing Mike down a little at a time. To wit, he says:
“While I agree that there is some research to indicate that global warming (possibly even anthropogenic warming) is occurring, exaggerations, lies, and politics only force people like me to discount almost everything we hear on the issue.”
Now I need to get Mike to be more open to seeing the exaggerations, lies, and politics on this issue that come from his sources. If he’s being “forced” to discount almost everything, it is because I have failed to fully persuade him that most scientists are like me, operating from curiosity and not from a political agenda. I need to persuade him that his notion of scientific conspiracies, whether imposed or unwitting, is the product of his political sources. Mike is smart enough to think critically, but, like all of us, he is captive to some extent by his world view.
For instance, Mike’s insistence that the mainstream media has not been covering “the other side” is simply false. Revkin’s article is but one example. The mainstream scientific media, likeAmerican Scientist, continue to provide a full and nonpartisan perspective.
As for “The Debate is Over,” I can’t think of a less productive statement. The scientific debate is never over. It just moves to new questions. And (of course) political debates never end. If I could get Al Gore’s attention about that, I would ask him to rephrase it this way: “The scientific consensus is compelling, and it says we have problems ahead. Although there is more to be discovered, we no longer have time to quibble about details. Let the political debate begin, and let’s watch the science carefully to make sure we stay on track.”
For people of all political persuasions interested in this issue, I recommend Chris Mooney’s upcomingStorm World: Hurricanes, Politics, and the Battle Over Global Warming, which I have reviewed for major metropolitan newspapers. When the review is printed, I will post it at http://www.scienceshelf.com/StormWorld.htm where I currently have the publicist’s comments.
Mooney’s conclusion is far less partisan than hisThe Republican War On Science. He notes a long history of creative tension between climate scientist empiricists who look for patterns in the data and theoreticians/modelers, who look for underlying principles.
He focuses not anthropogenic global warming, where there is broad consensus, but on the question of what warmer seas will mean for hurricane strength and frequency. The classic battle lines are still there, and it would be a great area to watch from the strictly scientific perspective. But one has to wonder if the current highly politicized environment has replaced creative tension with something much less productive.
Finally, I have had an interesting interchange with another conservative thinker at Chris Mooney’s The Intersection. He rightly pointed out that my use of the term “denier” or “denialist” sounds like I am equating him to those who deny the Holocaust. I will stop using that term. He’s a doubter, perhaps a megadoubter if I want to pull his chain.
By the same token, I have asked him to drop the argument about “The debate is over.” Having viewed the evidence with a skeptical eye, I find the scientific consensus compelling, and I think it raises important political issues. That’s where the debate is badly needed.
Fred Bortz
Science and technology books for young readers (www.fredbortz.com)
and Science book reviews (www.scienceshelf.com)
P.S.: If some A are B, and C is A, the statement “C is B” is neither true nor false, but inconclusive. That’s what I said
Fred,
Thank you for this blog. I have known about the Kilimanjaro issue for sometime, but of course we never read about this in the, “mainstream media.†While I agree that there is some research to indicate that global warming (possibly even anthropogenic warming) is occurring, exaggerations, lies, and politics only force people like me to discount almost everything we hear on the issue. Mix this healthy defensive skepticism with politicians (EU/UN etc.) who openly tie global warming with seemingly unrelated economic issues, and a huge credibility gap is created. I am very glad to read that you have acknowledged,†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 believe you are the first scientist that I have read (that agrees with the anthropogenic theory) that does not dismiss people like me as, “crackpots,†merely for calling for continued debate. I would argue that anyone who declares that, “the debate is over,†on ANY scientific theory (telephone for Mr. Al Gore) lacks all credibility. Your friend,
Mike
er,
Formal Logic dictates that the validity of the syllogism is FALSE, not “Neither”
The post correctly points out that premise (A)’s lack of the category “all” means that it appropriately reads:
(A)[some] Glaciers on Earth are retreating due to global warming.
Premise (B) may stand as written:
(B) The glacier on Mount Kilimanjaro is retreating,
The conclusion (C), reading:
(C) The retreat of the Kilimanjaro glacier is due to global warming.
is logically false.
Saying
some A are B
C is B
Therefore C is A
this is the fallacy of affirming the consequent (http://www.fallacyfiles.org/afthecon.html)
while, personally, I agree that more study is needed to link (or not) the Kilimanjaro glacier to warming, it is important that arguments be presented correctly.
For an early look at the tug of war over Kilimanjaro’s meaning, worth going back to a 2004 story of mine:
Times link (hopefully not fire-walled):
http://www.nytimes.com/2004/03/23/science/earth/23CLIM.html
Another post of same story as pdf:
http://stephenschneider.stanford.edu/Publications/PDF_Papers/Kilimanjaro.pdf
Not to belabor the point, and as a correction to my initial post,
If some A are B
and C is A
the statement “C is B” is an invalid conclusion and therefore not-true given the premises. It cannot be true without changing the premises (e.g. change “some” to “all”). That C is B may be true due to some other factors is possible, but does not logically follow from the premises you set out.
The point is that, because you position the argument as a test of deductive (i.e. syllogistic) reasoning and then promote a non-valid conclusion, people who may be sympathetic to the point of the article (i.e. that more study is warranted WRT the Kilimanjaro glacier) are instead diverted into either arguing about logical fallacies or dismissing the point altogether as illogical bunk (which it is not).
We’re making the same point. The premises “Some A are B,” and “C is A,” do not make it possible to conclude either that C is B or that C is not B. I’ve been saying that consistently in various ways.
My point is and has always been this: You can’t say that C (the recession of the glacier) is B (due to global warming) from the initial premises.
Your first comment on this was
“The conclusion (C), reading:
(C) The retreat of the Kilimanjaro glacier is due to global warming.
is logically false.”
That quoted comment is wrong. The conclusion C is logically incorrect (which was what I have been saying), but it is not logically false.
This time you say it is invalid. That’s fine by me. From the beginning, I’ve been saying it’s incorrect to draw that conclusion. It’s indeterminate. It’s invalid. It is not true, but it is not, as you said at first, false.
And that is enough of this silliness for me.
Fred Bortz — Science and technology books for young readers (www.fredbortz.com) and Science book reviews (www.scienceshelf.com)
In my initial posting, I asked to see the evidence that global warming may play a role in Kilimanjaro’s retreat. This morning, I discovered a pointer to this article at RealClimate.org from May of 2005 at another website where my blog entry generated some discussion.
RealClimate is very careful about its science and always cites its sources. Don’t take my word for it; visit the site and read the article in full.
For those who are content to read part of a single paragraph, I offer this:
“…Even more significantly, the Kilimanjaro glacier survived a 300 year African drought which occurred about 4000 years ago, as inferred from the ice core record [Thompson et al, 2002]. This drought was so severe that it has even been implicated in the collapse of a number of civilizations that were subjected to it. If the Kilimanjaro glacier has survived earlier precipitation fluctuations, what is different this time around that is causing its imminent disappearance, if not for something associated with anthropogenic climate change?”
Hardly a “smoking gun,” but an important perspective.
Fred Bortz — Science and technology books for young readers (www.fredbortz.com) and Science book reviews (www.scienceshelf.com)
My belief is such, much like that as “Is there a God?”…” I’d rather believe there is a God and find out there isn’t,” than “I’d rather believe there isn’t a God and find out there is.” In other words, what’s the harm believing global warming is due to it’s humanly inhabitants and take action to protect her and one another? Even if the catastrophic effects of global warming wipes out mother earth and ourselves as we know it, at least we’ll go caring about how are actions affect the earth and thus ourselves more… what can that hurt?
OhOh man… applying Pascal’s wager to climate change seems like an unnecessary step, katmarie. Although I suppose the wager’s pretty flimsy regardless.
Global warming impacts weather patterns, precipitation, etc. My understanding is overall Africa will become even drier (more famine, less water, and I’d expect probably less glacier too.