What part of that extreme was due to climate change?

Superb — and available! — story in this month's Nature on how researchers are beginning to parse the contribution of global warming to extreme events. Highly recommended. 

It's called "fractional attribution." Here's an easier way to grasp the concept:

Climateshift
To put it in English:

Inspired by the observation that intense rainfall in the Northern Hemisphere has worsened over the second half of the twentieth century, the group [of researchers in Canada] at compared actual precipitation data with simulations from six different climate models, both with and without greenhouse warming. They found that the extreme precipitation patterns observed did not match anything expected from natural climate cycles, but closely matched those expected from greenhouse warming.

As the story notes, it's much easier to quantify and predict temperature than precipitation, a far more complex phenomenon. This has been a stumbling block in climate science — and weather prediction, for that matter — forever, and it's a distinction the public seems unable to grasp.

Still, it's exciting to see the science going beyond the usual "it's impossible to attribute any one weather event to climate change" cliche. The public was able to grasp the idea of a percentage chance of rain on a given day; perhaps a percentage of attribution will also find its place in our thinking. 

Unlike more distant impacts of global warming such as the slowly rising sea level, the effects of local weather extremes tend to be instantly tangible and vividly remembered. Surveys suggest that people who feel they have personally experienced the effects of climate change are more likely to believe it is a real problem — and one that needs solving — than those who have not. 

Next challenge for reporters: find a "fractional attribution" expert willing to speak about this on a given extreme event. The problem (as Bill Nye recently alluded to, in a debate on Fox News) is that the analysis can take months, but even so, to talk about attribution at all is a big first step.   

Published by Kit Stolz

I'm a freelance reporter and writer based in Ventura County.

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