Attribution.

PrintActual conversation this morning between an anonymous atmospheric scientist and an intelligent, educated, cheery layperson in his life (also unnamed) but she-on-whom-his-sun-rises-and-sets, as they walked outside to the car:

He: This winter was warmer than usual.                                                                                     She (upbeat): Global warming!                                                                                                       He (unthinking, on autopilot): El Nino.                                                                                          She (only his imagination, or was there just the barest, momentary hint of chill in the air?): Is the planet warming or not?                                                                                             He: It’s warming.

_________________

As this vignette illustrates, attribution preoccupies us: why fix the problem when you can fix the blame?

Take climate change.

Atmospheric scientists have by and large agreed for some time that climate change is real, that it is largely human-caused, and that it poses possible opportunities but also serious risks for society. A recent George Mason University survey of AMS membership, though imperfect, nevertheless gives some feel for what AMS scientists think. From the executive summary:

Nearly all AMS members (96%) think climate change – as defined by AMS – is happening, with almost 9 out of 10 (89%) stating that they are either ‘extremely’ or ‘very’ sure it is happening. Only 1% think climate change is not happening, and 3% say they don’t know.

A large majority of AMS members indicated that human activity is causing at least a portion of the changes in the climate over the past 50 years. Specifically: 29% think the change is largely or entirely due to human activity (i.e., 81 to 100%); 38% think most of the change is caused by human activity (i.e., 61 to 80%); 14% think the change is caused more or less equally by human activity and natural events; and 7% think the change is caused mostly by natural events. Conversely, 5% think the change is caused largely or entirely by natural events, 6% say they don’t know, and 1% think climate change isn’t happening.

Read the original report in its entirety (please!), and you’ll find that AMS opinion is more divergent when it comes to the societal implications: for example, the extent to which human action can slow or reverse the effects of any warming; and the likely consequences climate change for the economy, hazards, and the environment. This is hardly surprising, given that the answers to these questions lie beyond the nominal boundaries of AMS-community expertise.

Outside the climatological community, as seven billion people continue to awaken to these realities and their implications, the global conversation has grown from a murmur into a full-fledged discussion, and, on occasion, debate. Much of that debate has been about attribution. At first people asked, are humans really the cause? Over the past decade, in part frustrated by perceived slow uptick of public concern, scientists added the following idea: you know, climate change is not just a slow small perturbation in average conditions. It’s producing dangerous changes in the location, frequency, duration, and intensity of extremes of heat and cold, flood, and drought, and other threats. What’s more, these altered patterns of extremes are significant contributors to the changes in the averages. This did rivet minds, but at the same time it ushered in a new arena for the attribution debate. People started asking questions, many ill-posed, such as: Was Katrina a global warming event? To what extent? What about Superstorm Sandy? How about last year’s record snowfalls in Boston?

All this history makes the recent NAS report, Attribution of Extreme Weather Events in the Context of Climate Change, especially welcome. The committee of experts authoring the report was chaired by Rear Admiral David Titley (retired). (Dr. Titley is currently Professor of Practice in Meteorology and the Founding Director of the Center for Solutions to Weather and Climate Risk at Pennsylvania State University and a Senior Adjunct Fellow at the Center for New American Security.)  He and the committee first addressed approaches to event attribution and then assessment of current capabilities for attribution. They suggested standards for how to present and interpret extreme event attribution studies. They closed by looking ahead, offering suggestions for improving attribution capabilities going  forward.

The March 20th episode of The Weather Channel’s Sunday program WxGeeks featured an engaging conversation on the report, featuring Dr. Titley and Dr. Marshall Shepherd, a University of Georgia professor and the show’s host – and also a member of the NAS committee. Here’s an on-line link to the show; it’s worth the viewing.

Bottom line: Attribution of Extreme Weather Events in the Context of Climate Change brings a nice framing to the topic of attribution and a sound foundation for future work.

Follow its guidelines and we’ll not only improve our worldwide dialog on fixing the blame, but also maybe return our focus to fixing the problem.

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