Conventional wisdom about climate change may have begun to gel in the aftermath of Sandy, but did global warming really cause the vicious hybrid storm that devastated much of the eastern seaboard last week? The short answer is no. Attributing Sandy or any other single event to long-term climate trends is rather like blaming El Niño for a car accident on the Santa Monica Freeway. But that's hardly an excuse for policymakers to keep kicking the climate can down the road. Science actually doesn't tell us much about that kind of causality, so it's time to stop acting like it does.
At its best, climate science deals in probabilities. This means that under ideal conditions, scientists can estimate how a given climate signal alters the chances of a particular event. For example, we can now begin to estimate how global warming changes the probability of destructive hurricane landfalls. But in the case of hybrid storms like Sandy, which combine hurricane and winter storm characteristics, science hasn't even progressed to the point of assessing probabilities.
Although this point may seem straightforward, it is routinely spun and misinterpreted. My colleagues and I try to make concise statements such as "Science has not established a link between hybrid events and climate change." But often, such statements are spun by climate skeptics into "Science has established that there is no link between Sandy and climate change." Others see Sandy as a harbinger of what climate change may look like, or emphasize (as I have) that sea level rise and increased atmospheric moisture can only worsen the effects of storms like Sandy.
But there is a more fundamental reason that science has failed to properly inform public debate -- its inherent conservatism. For scientists, an asymmetric reward structure means that it is better to be a little late in what proves to be an important discovery than to publish too soon and be proved wrong. As a result, scientists often ignore apparent patterns in their data if there is as little as a 5 percent probability that they could have arisen by chance. But while this philosophy makes sense for science, it can be disastrous when applied to risk assessment.
For example, the Fukushima Dai-ichi nuclear disaster occurred, in part, because the plant was built to withstand tsunamis triggered by offshore earthquakes up to magnitude 8.3 -- the largest earthquake that scientists conservatively estimated might be possible. But what was a "conservative" estimate for science was anything but conservative in the arena of risk management. Given the enormous potential downside, it would have made far more sense to build in a margin of error that might have withstood the magnitude 9.0 quake that did occur.