Articles by Andrew Dessler
Andrew Dessler is an associate professor in the Department of Atmospheric Sciences at Texas A&M University; his research focuses on the physics of climate change, climate feedbacks in particular.
An interview I recently did has been published in the newsletter of Caisse des Depots, a state-owned financial institution that performs public-interest missions on behalf of the French government. Also quoted in the interview is Patrick Criqui, Director of the Energy and Environmental Policy Department of the Grenoble LEPII. You can get the full newsletter here (PDF). It's all about the problems posed by the long timescale climate change operates on, and is definitely worth reading.
Here is the interview:
The answer depends on the exact question you're asking. Here is my view of the scientific consensus on a range of questions:
1) Did global warming cause Katrina? Or Rita? Or any single storm?
As far as I know, there exists not a single peer-reviewed article that connects global warming with the increased ferocity of any single storm. The commonly used dice analogy provides a good explanation of why the case is so hard to make. Assume the weather is determined by rolling a six-sided die, with a six corresponding to a massive hurricane. Now assume that by adding greenhouse gases to the atmosphere, we've loaded the die to make six come up twice as frequently.
Now, we roll the die once, and it comes up six. Did it come up six because it was loaded? After all, a normal die has a 16% chance of coming up six, so it's absolutely possible that the die would have come up six even without the loading.
So the answer to this question is "maybe, maybe not, we just don't know," and I think it's likely to stay that way.
No, the lesson is not that Katrina was caused by or made worse by global warming. There is, at present, no evidence that Katrina was meteorological payback for our ongoing emissions of greenhouse gases.
Rather, the lesson of Katrina is about risk.
The possibility of a large hurricane wreaking havoc on the Louisiana coast has been known for years. Everything from infrastructure damage to long-term flooding of New Orleans to the enormous refugee problem was foreseen in excruciatingly accurate detail.
We also knew the things we could do to reduce the impact of a killer hurricane. We could shore up the levees, for example, or work to recover the disappearing wetlands and barrier islands that shield New Orleans from storms. But these were deemed "too expensive" and postponed. We rolled the dice.
Now, our country is going to spend hundreds of billions of dollars to rebuild New Orleans and surrounding areas -- at least ten times more than the cost of mitigating the catastrophe in the first place.
What does this have to do with global warming?