Saturday, April 30, 2011

The Many Shapes of Climate Knowledge

After I gave a talk at Pennsylvania State University not long ago, a professor there asked if I could share the slide I use to describe one source of confusion and disputes when people are yelling about “global warming” or “climate change.” Here’s an improved version of the slide, which I hope helps reveal that the issue can’t be meaningfully discussed without getting into some more specifics:
Confusion and division over “global warming” often grows out of the meaninglessness of the phrase on its own. The result is that people with very different world views, in essence, create their own definitions of the term. (This is a point long made by Mike Hulme of the University of East Anglia, and is a central theme in his book, “Why We Disagree About Climate Change.”)
When you get more specific, you can see that the level of confidence and range of views* on each aspect of greenhouse-driven climate change, from the basic physics onward, has a different “shape,” as I’ve tried to depict above:
- More CO2 = warming world? Clearcut.
- How much warming? Durably uncertain.
- Extent of sea-level rise by 2100? Higher, but the worst case is durably uncertain — with the latest projections about what scientists were foreseeing in 1988.
- Hurricane patterns? Less clear than a decade ago.
In discussing the slide, I note that all ideas established by science have a shape. You can watch one iteration of my talk here (given at the University of Connecticut.) The structure of DNA is a spike. The process of natural selection is the same. Any discussion of global warming, whether in a news story or debate over policy or Gallup poll question, ideally should start with clarity about what’s being discussed. Otherwise murk and unnecessary confusion will follow.
Our deep, and normal, cultural differences pretty much guarantee this result. Combine that mix of shapes with the “Six Americas” bubbles illustrating the wide array of views of climate change among American citizens and you can see the challenge. Read More

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