Richard Seager’s new paper on Georgia drought has been well-covered by Cornelia Dean in the New York Times, and I’ll let her make its central point: that Atlanta’s problems “resulted from population growth more than rainfall patterns.”
Seager and his colleagues point out something that I banged away on a bit a couple of years ago – that the parched years that dried out Lake Lanier, which serves Atlanta’s water, were nothing out of the ordinary range of variability. (But they’re real scientists publishing in the peer-reviewed literature. I was just engaging in blog science.)
The Atlanta affair was a bit of a puzzle for those of us out West who think of drought and climate variability in very different ways. Here, climate varies on decadal scales – the “drought of the ’50s”, for example, arguably stretched from the late 1940s into the 1960s, or possibly, depending on how you measure, into the 1970s. It ebbed and flowed over both time and space, with wet places and wet periods interspersed among the dry, but it was a long haul.
Similarly, the wet period that followed stretched from the mid-1970s to the late ’90s, before things started drying out again.
That decadal-scale variability is a characteristic, Seager and his colleagues write, of climate variability in the central and western parts of North America. On the east coast, droughts are a phenomenon of one to a few years, and periods as dry as the most recent one are a common feature of the Georgia climatology. But in the period between the last time this happened and the 2006-2008 drought Georgia’s population grew nearly 50 percent. Also worth noting – the period during which most of that growth occurred was unusually wet.
As I said back then, “If you can’t handle events within the normal range of variability, you’re screwed.”
Dr. Seager and his colleagues have a great set of web pages summarizing their drought research. Their work is a model of good outreach beyond journal publication to the interested public. The Georgia stuff, including a link to the Journal of Climate paper, is here. Their main drought page is here.