September 12, 2017

Matt Ridley isn’t afraid of Hurricanes

In The Times, Matt Ridley writes a familiar post-massive hurricane storyline. I would summarize it in three parts: There is little to no evidence that climate change has altered the frequency or character of hurricanes or tropical cyclones; that wealthy weather storms better than the poor; that adaptation to climate risks has advantages over putting downward pressure on emissions.

Let’s take them in reverse.

That adaptation has advantages over mitigation is probably right. But so too does mitigation have advantages over adaptation. They do different things and work different ways. Adaptation is local, ongoing, and mostly private. Mitigation is global, permanent, and cooperative. Their disparate characters are important, because mitigation is what satisfies our obligations to future generations. People in Houston, Florida, or in future storm events have done little to add to climate change, so expecting them to spend to adapt to higher risks imposed by historical emissions is unjust.

The idea that we can enhance the adaptive capacity of people in the future by growing wealth is solid, but has serious limitations if you want to argue that mitigation policies aren’t worth it. Large hurricanes have historically led to prolonged decreases in economic growth. So allowing their impacts to grow under climate change is potentially very costly.

In Ridley’s piece, the key passage on the climate effect on hurricanes is here:

An analysis published last month by the American government’s Geophysical Fluid Dynamics Laboratory stated: “It is premature to conclude that human activities, and particularly greenhouse gas emissions that cause global warming, have already had a detectable impact on Atlantic hurricane or global tropical cyclone activity.”

Interested readers should check out the analysis Ridley quotes, which reviews the state of the science on how climate change will affect hurricane frequency and characteristics over the 21st century. It cites climate models that show intensity increasing by 2-11 percent on average, and potential damage increasing by 30 percent by the end of the 21st century. However, it explains we have not observed such changes to high statistical confidence yet, because the climate effects are still predictably small and observations from before the satellite era are too spotty to beat out statistical noise. While strong, wet, storms fit expectations under global warming, we won’t be able to make confident claims about trends in hurricanes until mid-century. Global trend analysis, however, is not the only interesting question to ask.

We are sure to see studies of Harvey and Irma in the coming months and years that look at these storms as individual events, and the meteorological conditions they developed in, to suss out any connections to climate change. My bet is those studies will find a small contribution to rainfall totals and intensity, but we’ll see. We already have evidence showing that climate change increases impacts of major storms because sea level rise gives flooding a boost (h/t @PeterFrumhoff ).

So while there is much correct about Ridley’s story, I think it misses the point. Climate change is just a part of every story now. Storms and extreme weather events will probably become more familiar, and adaptation will lessen the blow as wealth continues to accumulate. The question is, how much change do we want to countenance—and there, Ridley has little answer.

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