What we need is an attribution system, operated regularly like the weather forecast and made available to the public. Its purpose would be to deliver rapid and authoritative assessments of the links, if any, between recent extreme weather events and human-induced climate change.
In the event of, say, a severe flood, the system would provide estimates of the extent to which the event was made more or less likely by human-induced climate change. It would also take into account alternative natural explanations such as the El Niño Southern Oscillation, a large-scale climate pattern in the tropical Pacific Ocean that affects weather worldwide.
We expect such a service would be of great interest to anyone who wants to know whether a given event could be attributed to climate change, from politicians and journalists to homeowners and insurance companies.
Are we capable of delivering? Attribution is difficult and it will be important not to undermine the credibility of a system by prematurely attributing events. However, climate science has advanced to the point where it is possible to assess some types of weather event. For example, the European heat wave of 2003 was consistent with an increased risk of extreme weather caused by climate change, whereas the cold U.S. temperatures of 2008 were not—instead being linked to the La Niña phase of the El Niño.
For other events, such as hurricane Katrina and last year's devastating Pakistan floods and Moscow heat wave, the cause remains uncertain. But the development of an attribution system should help drive further improvements in the forecasting models by continually confronting real world examples of extreme weather.
We at the Met Office—the U.K.'s national weather service—are keen to take this idea forward, and have begun to put together an international collaboration of scientists called the Attribution of Climate-related Events Initiative, or ACE for short. Our aim is to understand when we can reliably estimate the odds of particular types of extreme weather events and for which types of events further improvements are required. We hope to have a prototype attribution system up and running in two years.
Should another Category 5 hurricane make landfall on the U.S. mainland, its attribution will be tough. But scientific understanding is developing all the time. Were an attribution system established and its strengths and limitations well understood, a future judge, journalist, or local resident, interested in who—or, indeed, what—to blame, would know where to go.
This article originally appeared in New Scientist.