Monday, December 14, 2009

Weather Ain't The Same As Climate Mr. Aiyar

It's amazing how much confusion there still is between weather and climate.

Mr. S A Aiyar writes a well read and well respected economics column in the Times of India. I like his columns. He has a gift for explaining complex topics in a succinct and simple manner. He gets it right a lot. Rarely though is he so completely wrong.

Like here where he tries to explain why climate projections can't be trusted:

If new technologies cannot reduce emissions by 80% save at a huge cost that causes economic distress, governments will abandon emission targets. They will not deliberately create deep recessions just to curb emissions.

Will this lead to climate disaster? Maybe and maybe not. Scientific knowledge of the weather is very limited, and Intergovernmental Panel on Climate Change (IPCC) projections are just intelligent guesstimates. IPCC scientists may be the best in the world, yet they cannot predict the weather more than five days ahead.

Can they predict the next drought in India? No. The next El Nino? No. The number of hurricanes in the Caribbean next year? No. So, can they accurately predict the weather 100 years hence? Surely not. When we know very little about a problem, we tend to worry endlessly about worst-case scenarios. That does not make the worst case certain, or even probable.

He's right when he says that climate scientists cannot predict the weather 100 years hence.

But they are not trying to. That's not what climate scientists do.

Weather is the day to day or short term atmospheric conditions. Climate and climate change is about long term changes in average weather. If you want to know what the weather will be on a Sunday 100 years from now you will still have to rely on a meteorologist to tell you 3 days before that Sunday.

Climate scientists on the other hand will tell us that if you take a ten or twenty year interval 100 years from now, the average temperature of that interval will be higher than today.
That much is a near certainty and it follows from the basic greenhouse effect. If we keep emitting greenhouse gases the earth will warm up. What is uncertain is by how much and what exact regional effects will it have. That's where the climate models and IPCC projections come in. And they show a range of possibilities depending on assumptions made of starting conditions, emission trajectories for different economies and not yet well understood positive and negative feedback's in the climate system.

For drafting sensible policies to reduce emissions we don't need to know whether a series of powerful hurricanes will hit New Orleans in year 2102 or whether they will hit it in 2105 or the exact year in which India might face a crippling drought in the future.

Its enough to know that 100 years from now these events will be more common (update: or more intense). And our current and improving understanding of climate change does provide enough confidence on that issue, more than Mr. Aiyar wants to give it credit for.

Its a shame that a person as erudite as Mr Aiyar has misrepresented climate science and misinformed the public in so blatant a manner.


  1. From what I know about Global Warming, wouldn't it reduce the temperature gradient between the tropics and the poles, thereby reducing the number of violent hurricanes and storms?

  2. This is strange and very very unexpected from someone of Mr. Aiyar's background. Surely being an economist he knows about statistical models and large scale predictions and things like that.

    I have no idea, but i will venture a guess that even macroeconomics is built on somewhat similar platform...

    Disappointing to say the least.

  3. nothing unexpected from a Cato institute member

  4. Ambuj- For the north Atlantic basin the model results are equivocal on the frequency but agree that intensity will increase. that coupled with sea-level rise would mean greater impact on coastal cities.

  5. I guess I have to take the assertion at face value because it is counter-intuitive.

  6. Ambuj- as I understand the two don't have to change in a similar manner. take a look at this article which lays out the complexity. link to primary research also there.

  7. I am not comfortable with their reasoning. Based on the research, they conclude that (a) There is anthropological global warming, and (b) There will be increased frequency of TC in Atlantic in the coming years. However, they jump to another conclusion that "(a) is the cause of (b)", although in the main body of article itself they have identified ENSO as a dominant variable in TC frequency. They seem to be treating coincidence as causation.

  8. Even the researchers whose work indicate uncertainty in future hurricane frequency trends don't - according to that post - dispute that the current increase observed in Atlantic hurricane frequency is due to increased sea surface temp which most work indicates is due to anthropogenic induced warming.

    Also there is still a lot of uncertainty about ENSO future variability trends according to the IPCC models.

    I guess we can keep quibbling about this for ever.. :)

  9. This is very well and clearly said. You clean out the drains before the monsoon not because you know what day they will arrive but because you know they will likely arrive (unless the changing climate cancels them!) In our current situation, I would think the conservative approach would be to do something serious about climate change. I see many people looking for excuses to do nothing or very little.