Fighting ignorance since 1973 Its taking longer than we thought
So when does
global warming get to Chicago?
Not a week goes by, it seems to me, that I don't hear about new evidence of
global warming. The ice caps are melting, droughts and hurricanes are
increasing, and now I see where the mountain pine beetle, no longer kept in
check by now-mild Rocky Mountain winters, will soon wipe out the lodgepole
pines of Colorado. Then I look out my office window here in Chicago, see
what remains of the snow, and remember a month's worth of ice storms, subzero cold, and
near-constant scraping and shoveling. Naturally I think: so when does global
warming get here?
Not that I would ever doubt Al Gore, or wish ill on the rest of the planet,
but we could use a little of that global warming action, and so far I'm not
seeing much. What gives?
I call your attention to the above map, the handiwork of Noah Diffenbaugh, head of the Purdue Climate Change Research Center. (Here's a bigger version.) It appeared in a 2008 paper he coauthored entitled "Climate Change Hotspots in the United States." We'll get into the details in a bit, but first take a gander at the map, which purports to show how the contiguous U.S. and parts of Mexico and Canada will be affected by global warming by the end of this century. Colors on the left (low) end of the scale indicate regions that, relatively speaking, will get a pass, climate changewise. Colors on the right (high) end show areas that are going to catch it in the neck. Several things jump out at you, the most important of which from our standpoint are these: (a) things are going to be comparatively tranquil in the eastern half of the country, but (b) one of the exceptions is us.
A few other general observations:
Speaking of 2071, you may wonder where a profession that can't reliably forecast the weather next week gets off predicting what's going to happen 62 years down the road. Presumably the operative philosophy is: one's reach should exceed one's grasp.
Then again, I note that among the regions predicted to be least affected by climate change, as indicated by dark green and blue on the map, are (a) the gulf coast, much of which was reduced to rubble by Hurricane Katrina, and (b) the state of Georgia, which is coming off a three-year drought. So, with all respect to the distinguished scientists who developed it, I wouldn't rule out the possibility that the climate-change modeling algorithm still has some bugs.
Back to that apparent hotspot around Chicago. I've studied Prof. Diffenbaugh's paper and spoken to him on the phone. Not to belabor the point, but hotspot doesn't mean hot. It means a region more likely than average to see change. Here I think Diffenbaugh's work has benefited from his having spent the past few years at Purdue. All midwesterners recognize the dramatic swings of climate to which the region is prone. If it's 110 degrees one day and 8 above zero the next, you may say on average the weather's nice. However, this statement glosses over significant nuances. Likewise, when the 2001 report from the Intergovernmental Panel on Climate Change says broad swaths of the U.S. will be slightly warmer and experience a little more precipitation than average in winter, the veteran midwesterner thinks: I bet there's a lot they're leaving out.
To deal with this problem, Diffenbaugh and his colleagues did a couple of shrewd things. First, they analyzed much finer-grained geographic detail than previous researchers, using a model that divided the country into a 25-kilometer grid. Next and in my opinion this is the real breakthrough they studied climate change not per year but per six-month season, April through September and October through March, lest offsetting changes in the two halves of the year cancel each other out. An impatient midwesterner who's had a spring picnic ruined by a sudden 25-degree drop may object: I'll be impressed when the climate-change timescale gets down to every fifteen minutes. I won't argue. But this is a start.
Anyway, here's a distillation of what Prof. Diffenbaugh had to say:
Diffenbaugh, N. S., F. Giorgi, and J. S. Pal (2008), "Climate change hotspots in the United States," Geophysical Research Letters (2008), v. 35, L16709: http://www.purdue.edu/eas/earthsystem/Diffenbaugh_GRL_08.pdf
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