Wednesday, October 24, 2007

Droughts, growth and climate change

From the Baltimore Sun, "Bay and Environment" blog:

Prettyboy Reservoir

It's dry out there. Is it just another natural cycle in the weather, or a sign of long-term changes in climate that many scientists warn are coming? A story in today's Sun by Frank Roylance reports that long-range weather forecasts see no relief through next spring for the near-record drought gripping Maryland. Stream and ground-water levels are at or approaching record lows in Central Maryland and the Eastern Shore, with some of the fastest growing parts of the state most affected.

Looking around the country, there are similar reports elsewhere. The Southeast is suffering its worst drought ever, The New York Times had this story about the even more severe drought conditions across the Southeast. With less than four months' water left in the lake supplying the sprawling Atlanta metro area, Georgia's governor declared a state of emergency for more than half of the state. Another story in the NYT noted how the Great Lakes are low as well - and while their water levels rise and drop as the seasons change, there's been less-than-normal rain and snow to replenish them in the past couple years.

Of course, it's a stretch to pin any area's unusual conditions on climate change, as droughts come and go. Also, the most dramatic impact predicted from global warming is one of too much water - rising sea levels and destructive storms. New Orleans, still struggling to recover from devastation in 2005 by Hurricane Katrina, was flooded again today by torrential rains.

But climate scientiest also predict that warmer temperatures can make dry areas drier, causing more water to evaporate from reservoirs and rivers while also preventing the buildup of snow in mountains that replenishes water supplies every spring when it melts.

In that vein, the NYT magazine on Sunday had a cover story headlined "The Future is Drying Up" warning of potentially catastrophic water shortages in the arid West, where surface water supplies are dwindling and scientists warn that changing climate could diminish the mountain snowpacks that replenish the reservoirs and rivers sustaining the farms, ranches and cities of the region. The story quoted the water czar for Las Vegas saying the rapidly growing city already is the first U.S. victim of global warming.

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