The climate bats last…
As an international media storm continues to rage over allegations of fraud by the Intergovernmental Panel on Climate Change and its director, Rahendra K. Pachauri, new research suggests that a warming world will bring drier conditions to the already drought-stricken American Southwest.
As part of the research, published last week in Nature Geosciences (sub req), scientists gleaned a new climate record from stalactites and stalagmites in a New Mexico cave. The record suggests that warming will “lead to increasingly arid conditions in southwestern North America in the future.”
Credit goes to my colleague John Fleck of the Albuquerque Tribune, one of the nation’s top science writers, for highlighting this new research in a story (sub req) and in a posting at Inkstain, his personal blog.
The researchers say warming temperatures tended to nudge the jet stream over North America to the north, as is depicted in the map above. (The map also depicts shifts in the Intertropical Convergence Zone, where trade winds originating in the Southern and Northern Hemispheres converge.)
It’s the jet stream that typically steers winter precipitation into the American Southwest. So with a northward shift, winter snows bypassed the American Southwest, resulting in dryer conditions.
Scientists have already documented a northward shift of the jet stream in response to current global warming. And computer simulations of a warming climate have predicted that northward shifts of the world’s jet streams would occur. Now, the research by Asmerom and his colleagues documents that this has actually occurred in the past.
The findings are “particularly ominous for drought-sensitive regions, such as the western United States,” Asmerom and his colleagues write. And if future warming unfolds as it did at the end of the last interglacial period — suddenly and rapidly — the Southwestern United States could be pushed “into an even more arid phase, unseen since the early Holocene, or even go beyond this, into conditions not represented since 125,000 [years] ago.”
Meanwhile, the Southwestern United States remains in the grip of a drought that began in October of 1999. According to the U.S. Bureau of Reclamation, Lake Mead in the lower Colorado River Basin stands at just 44 percent of capacity. And there’s very little hope of recovery in the short run. The flow of the Colorado River from April through July is forecast at 6.0 million acre-feet, or just 76 percent of average.
Once again, nature is trying to tell us something. Are we simply too distracted by politics, ideology and good, old-fashioned scandal, to listen?