While New York is still drying off and taking account of the Hurricane Sandy aftermath, a new study in Environmental Research Letters has a warning about the other, much drier side of the global warming coin. While large-scale climate change can bring the rain in destructive, terrifying volumes, it can and almost certainly will take that rain away from places that need it, like India (and also the United States, though the relationship between either India or the United States’ current droughts and climate change is not settled [somewhere between “maybe” and “probably”.]) At risk in India are the country’s yearly monsoons, which the nation’s farms — employing a full half of the Indian population — depend upon.
The focus of this week’s ERL paper is, specifically, the Pacific Walker circulation. This circulation is a massive weather pattern that tends to drive moist, surface air west across the Pacific Ocean, where once it reaches land, the air rises, releases its moisture as rain, and then heads back east drier and at a higher altitude. Every few years, this pattern reverses as a result of El Niño, and you have drought in India. What the research shows is that as global temperatures rise toward the later parts of this century, El Nino events will no longer be needed to cause disruptions in the Walker circulation. Indian droughts will no longer be the exception, but the norm.
Of course, the Indian economy is changing and by the time the country really dries up, maybe its populace will be enjoying some sort of brilliant techno-future of super-industrial farming yielding even more abundant crops on less water while the job market shifts even more to technology and other fantastic things TBD. Let’s hope.
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