Wednesday, August 09, 2006

Regional predictions

Take a look at this interesting editorial in the Rocky Mountain News. In it, they talk about whether regional forecasts of climate change are accurate or not:
The majority of scientists working with the United Nations' Intergovernmental Panel on Climate Change think not. The San Francisco Chronicle reported last month that most of them find local climate projections unreliable.
I agree with much of what's in the article, but one thing I disagree with is:
Pielke dismissed the paper on his Climate Science blog (, stating that Diffenbaugh's method of prediction is not accurate enough to "add appropriate insight to be used by policymakers."

Christy, who's also Alabama's state climatologist, also distrusts localized forecasts. He told the Chronicle, "I would not base economic decisions on the output of regional predictions from these models."
One point I make in my book and here on this blog is that decisions to act are ultimately value judgments. While Pielke Sr. and Christy might not be moved to act based on a new scientific research, that does not mean that everyone shares their values. If I owned a bed and breakfast in VT and much of my business was based on tourists coming in to see the leaves turn every Fall, I'd be very concerned about changes in the New England climate, and might be spurred to act by this new research, even if others were not swayed.


Anonymous said...

It's hard to get too much confidence in these computer simulations, there is too much unknown and unknowable to build a computer model with any credbility in my opinion. This study, which I criticized when it was published 2 years ago has so far proved to be wrong big time :
The last 2 years are almost the opposite of what it predicted, so how long would you wait to see if it averages out and is right 30 years from now? How many long term investments would you make on this model? If you were a betting man, would you bet next year would be like the model or not? Anyone know of some regional models made within the last 5 years that have panned out? Maybe my database is too small.

M.J. S. - (Wacki) said...

"If I owned a bed and breakfast in VT and much of my business was based on tourists coming in to see the leaves turn every Fall, I'd be very concerned about changes in the New England climate, and might be spurred to act by this new research, even if others were not swayed."

There are a lot of convincing arguments you could of used. However, this is simply not one of them.

Anonymous said...


The trouble with your argument is that it applies equally well to psychics as it does to GCMs. Of course, all decisions about the future are value judgments and no one is arguing that we must be absolutely sure before we can decide anything. It is a question of the value of the information on which we base our decisions. Computer models will tell us about the future, as will psychics. Why should we listen to either one if neither shows any skill?


Equating the use of (often wrong) economic models with the potential use of global climate models for developing policy, is not a persuasive argument. Your acknowledgement of the failure of the economic models is actually a strong argument against using GCMs to develop policy, for economics is arguably easier to model than climate change.

There is a fundamental difference in the decision making processes of economics and climate change. In economics, decisions will be made regardless of the existence of economic models. People have been making these decisions long before computers were invented and will continue to make them well into the future. The existence of the models does not change the need to make these decisions.

In climate change, it is the models that create a need to make a decision were no need existed before! If the models have no skill, then there is no need to try and regulate or prevent man-made climate change! No decisions need to be made; no actions need to be taken, for there would be no defined problem!

This alone would suggest that we should demand a lot more accuracy from the climate models than we do from the economic models. On top of that, the proposed ‘solutions’ to the virtual problem of man-made global warming place a cost and hardship on everyone on the planet!

In light of this, it seems very reasonable that we confirm the models have significant skill before acting upon them, and very unreasonable to suggest that we should ‘act’ on what can only be described as ‘faith’ in the models.

There are many known problems that require our attention. Solutions to some of these problems would likely mitigate our impact on global climate. Taking resources away from these problems to try and control global climate change (which is arguably impossible) is a lose/lose proposition.

Andrew Dessler said...


Your argument is based on the assumption that models have no predictive ability. As a climate scientist (although not a modeler), I'm familiar with a lot of literature showing that models do a pretty good job of simulating our climate. Not perfect, mind you, but good enough that we should take their predictions seriously.

I'm wondering what peer-reviewed publications you've read that suggest that models have zero skill at predicting the future cliamte?

Thanks in advance for the citations.