Monday, July 16th 2012, 1:40 PM EDT
It’s difficult to deny that large areas of the US are undergoing drought conditions at the moment. But should we be assuming that this is a portent of climate change? Or even that it is a harbinger of a new Dust Bowl, as in the 1930? We cannot completely rule out either of those possibilities but the correct answers as yet are no and no.
That there are drought conditions in many places is not in doubt:
In a monthly report to be released Monday, the National Climatic Data Center is expected to announce that this year’s drought now ranks among the ten largest drought areas in the past century.
Preliminary data computed from the Palmer Drought Severity Index shows that 54.6 percent of the contiguous 48 states was in drought at the end of June, the highest percentage since December 1956, and the sixth-highest peak percentage on record.
Monday’s State of the Climate drought report from NCDC is expected to show that since 1895, only the extraordinary droughts of the 1930s and 1950s have covered more land area than the current drought.
Note that we’ve only really had accurate rainfall and drought measurements for much of the US since that 1895 date. So, leaving aside specific years and looking at groupings, we’ve got the third worst drought conditions in just over a century. No, this isn’t to be ascribed to climate change then, obviously. As I say, it could be of course, but the prima facie answer is that it is not. For we’ve had it worse, twice, before in periods when we really were not worried about anthropogenically caused climate change. Occam’s Razor would so far lead us to the thought that it’s just one of those things that happens in a the normal variations of something like weather.
The second worry is that even if it is just variation, might it still lead to Dust Bowl conditions? The thought of 95% of the topsoil in the mid-West landing on the Ozarks (I might be exaggerating a touch for effect here) isn’t all that pleasant a one. This seems most, most unlikely.
That being said, differences in land use and farming practices since the Dust Bowl make the comparison of real-world impacts more complicated. Erosion-control practices and drought-resistant crop hybrids are just two examples of ways in which modern agriculture attempts to mitigate the impacts of severe drought.
The thing is, last time around, when we did get the Dust Bowl, we were really only just beginning to understand about the effects of ploughing with tractors on the stability of that topsoil. We have rather learnt some things in the intervening 80 odd years. Don’t plough so deep, don’t leave the earth uncovered, use no till methods if you can, plough around contours not up and down them and so on. So, again it is possible that we’ll have a new Dust Bowl: maybe the things we’ve learnt aren’t enough. But that isn’t he way that anyone’s actually betting at this point.
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