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Saturday, August 06, 2005

A vortex in the Met Department

A few days back S R Kalsi, the additional director general of meteorology, had forecast in an interview that we took rather seriously that there would be heavy rains "any time on or after August 5". Well, yesterday was August 5, and the weather's been a tease since then, often overcast, hardly drizzling. Could it be -- shock, horror -- that Mr Kalsi did not know what he was talking about? The Telegraph reports:
The meteorology experts, who had failed to predict last week’s deluge in Mumbai, today said they haven’t yet found out why it happened.

Still, at a post-mortem of the record 944 mm rain that traumatised the city on July 26, weather scientists tried to come up with a theory before science and technology minister Kapil Sibal. They said they suspect a meteorological condition called a “vortex” caused the freak rain.

They admitted they had no evidence for this.
Another excerpt from the article:
[Akhilesh] Gupta [a scientist] said the UK weather office did manage to predict 800 mm rain over Mumbai when it ran a computer model; but it could do this only after the event, using weather parameters after the downpour. “It could not predict the Mumbai rain in real time,” Gupta said. [My emphasis.]
All of this underscores how little we understand the weather, and how ludicrously inexact all these complex weather forecasting models are. And it amuses me that when we can barely predict the weather a week from now, we have environmentalists pontificating on weather changes that global warming will cause a century from now. How can one not be sceptical?

10 Comments:

Anonymous Karthik said...

I understand the sentiments that inspired this post, but the argument at the end is a little disingenuous.

In most complex systems (weather, stock market etc) it is extremely difficult to predict short term events (Will it rain tomorrow? Will the Dow go up next week?), but predicting the overall trend is something that existing models do reasonably well.

Plus India's meteorologists (IMO) aren't as good as their counterparts in the West - look at the glaring contrast between weather reports in the US vs the weather reports in India...

Sat Aug 06, 04:44:00 AM GMT-7  
Blogger amit varma said...

I'm afraid, Karthik, that existing models have done a terrible job of predicting long-term trends with either the weather or the stock market. Remember the scientists who predicted global cooling in the 1970s? Or the long-term projections of stock-market analysts of the 1990s?

No one could examine the evidence and think that overall trends in these two fields can possibly be forecast accurately, unless you have a confirmation bias on the subject, in which case you might as well believe in astrology as well.

Sat Aug 06, 05:17:00 AM GMT-7  
Anonymous Karthik said...

Could be my confirmation bias or your disconfirmation bias ;)

A majority of researchers seem to believe that the earth is getting warmer, and will continue to do so in the future. Even Lomborg concedes that global warming is probably here to stay, but he seems to disagree with the rest of the scientific world on how much of an effect will this have. (This study by the Scripps institute seems to be a reasonable indicator of this phenomenon as well...)

How good are the long-term models? I don't know for sure - guess no one can. I just think that extrapolating the inability of a few meteorologists to predict the rains in Mumbai to question a whole body of work on global warming is a little bit of a stretch.

Sun Aug 07, 03:32:00 AM GMT-7  
Blogger amit varma said...

Hmm. We'll just have to agree to disagree, I guess, Karthik, or discuss it in a more appropriate forum. But as far as long-term models are concerned, let me just say that similar long-term models have failed in the past repeatedly, so we don't actually need to wait to pass judgement on them. In fact, my scepticism of them is based on a lot more than this particular minor failure of the met 'scientists', so if it appeared that I was extrapolating from this, then the fault must lie in my phrasing.

The issue is not of whether global warming is happening or not, but its extent and cause, and whether it will continue. Global cooling was in vogue in the 1970s, and the temperature of the arctic, the poster region for environmentalists, was pretty much the same as now in the 1930s, and rather warmer in the last century. Then it got cooler, then it got warmer (while the Antartica has actually got cooler in the last couple of decades), and we don't know why it happened then, and the guesses about why it's happening now are just that -- guesses. (And guesses that mistake correlation for causation.) How little we understand the weather is underscored by both those macro-failures, and by smaller ones like this. That was my point.

I don't intend to say that we should not curb our use of carbon fuels, which are clearly harmful. But just that we should be humble, and acknowledge that the way the world's weather functions is still a mystery to us, despite the pontification of "experts".

Matt Ridley in "Genome" compared Global Warming, in its pseudo-scientific nature and the seeming scientific consensus that built up around it, to eugenics. I'd say that's about right.

Sun Aug 07, 05:33:00 AM GMT-7  
Anonymous sachatur said...

Sorry to post a seemingly off topic comment.
This comment is about a post titled "A lot of hot air" on Amit's blog that links to
this blog, and is tangentially related to this post...

Amit,

I'm a regular reader of your blog. I agree with most of your analyses and positions. Your post on Global warming, "A lot of hot air", on 17th August 2005, however, seems to be a blatant misrepresentation.
Could you be guilty of the same thing you accuse others of: "A Confirmation bias?"
The focus of the article "Heat and Light" in the Economist, is not "...the latest failure of the computer models that climate scientists love to boast about." as your excerpt suggests, but actually, the publication of three papers in the journal 'Science' that suggest that the "...anomaly in the climate seems to have been the result of bad data."

Could this be a case of "Association Fallacy": The left is wrong. Global warming is a pet cause of the left. Therefore global warming is wrong?

Maybe you missed it, but isn't it ironic that your position that "One of the most pernicious myths of our times is that there is a "scientific consensus" that global warming occurs" sounds exactly like the position creationists/IDers hold, that scientific consensus on evolution is a myth?

Fri Aug 19, 08:22:00 AM GMT-7  
Blogger amit varma said...

Heh. Sachatur, one para after accusing me of the "Association Fallacy", you commit it yourself!

Anyway, as you have just got personal and not actually made any arguments, I have nothing to counter. The data is out there, and I've linked to it enough. Follow the links.

Fri Aug 19, 12:01:00 PM GMT-7  
Anonymous sachatur said...

Amit,

Where did you get it that I was getting personal? I was just inviting you to examine your position from another perspective. Why is attacking your position, and your syllogism a personal attack? Maybe I'm missing something.
Anyway, all I was doing was pointing you to your erroneous(in my opinion) precis of the article in 'The Economist.' You can surely counter that!
Re. my association fallacy, Touché!

Fri Aug 19, 01:39:00 PM GMT-7  
Blogger amit varma said...

It wasn't a precis but an excerpt. And it was hardly a misrepresentation, as the conclusion of the piece, as stated in the last para, mirrors my beliefs. Here it is again:

"Studying the climate is a hard problem for three reasons. The system itself is incredibly complex. There is only one such system, so comparative studies are impossible. And controlled experiments are equally impossible. So there will always be uncertainty and therefore room for dissent. How policymakers treat that dissent is a political question, not a scientific one."

I suppose I shouldn't have accused you of getting personal, but accusing me of "a blatant misrepresentation" seemed like that when I read it. Anyway, that's cleared up now.

Fri Aug 19, 02:18:00 PM GMT-7  
Anonymous sachatur said...

Yes indeed. This might sound like much ado about nothing, and like we are agreeing vehemently, but here I go again:
Having been a regular reader of your blog, I realize that the conclusion in the article mirrors your position, but do you see the apparent confirmation bias in your selecting the paragraph you excerpted, and the intro that precedes that excerpt?
Read in exclusion (which I bet most of your readers will be forced to do, since the article is/will soon go behind a subscription wall), the paragraph excerpted suggests, like your intro to the excerpt does, that it is about "...the latest failure of the computer models that climate scientists love to boast about." It most certainly is not about that! You will surely agree that this seems to be a "blatant misrepresentation."
Also, having been a regular reader of your blog, and having understood your position on evolution, I couldn't dream of associating you with Creationists/IDers. So I hereby retract the Touché! Hehe!

Fri Aug 19, 08:16:00 PM GMT-7  
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Wed Sep 16, 01:30:00 AM GMT-7  

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