Friday, February 18, 2011

More about the rain

Further to the post below about a couple of Nature papers on the connection between an increase in Northern Hemisphere precipitation and global warming, I can't say that I have seen any substantial Australian media reporting on this yet. (OK, there are short reports, but they certainly haven't been front and centre on websites.) I would have thought they would have attracted more attention here, given our wet, wet summer. (Darwin has just posted a record 24 hour rainfall, which seems pretty remarkable for such a famously wet place.)

But I also see that Andy Revkin is complaining that the Nature abstract, and media reporting, is overselling the papers and overlooking the caveats that appear in the studies themselves. Revkin's post contains much by way of explanation from climate scientists, though, as to how this happens. Real Climate's post on the topic certainly does not oversell it.

Roger Pielke Jnr, meanwhile, continues his "nothing to see here until I say you can see it - in about 30 years time" routine on climate change, by emphasising that, just because it rains more under a warmer climate, it doesn't mean you can say this is connected to worse flooding. As someone in comments notes:

Also I think it will eventually strike many observers as, well, hairsplitting, to argue that a trend of increasing intensity of rainfall events cannot be connected to human well-being unless and until we can show that flood damage unquestionably rises even controlling for all other contributing factors. All analogies are flawed at some level, but its a bit like seeing sparks from a distant fire settle onto one's rooftop, and not worry about them because, watch as you may, they just keep going out. Rain events and major snowmelt events cause floods when they get intense enough, this is like saying a driver who has many close calls is likely to have a serious accident eventually. Even though other things (previously saturated soil for example) certainly help set the stage.

And why just focus on flood? What about the other harms almost surely associated with intense precipitation (rain or snow) events, like traffic fatalities during the events themselves? And for intense rain specifically (but also large snow melt events), how about soil erosion on hill sides (even gently sloping), and sewage overflows into harbors and streams, and leaching of nutrients from lawns and farm fields, and deer kills in deep snow?
Well, the last point about deer kills in snow is an example too far, but I agree generally.

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