Storms Increase Since 1900 Global Warming May Be Cause Of Gradual Rise In Wet Weather

Forty inches of rain falls on the Sierra Nevada in only five days. Minnesota exhausts its snow removal budget by mid-January. A Navajo reservation sits isolated by a blizzard in Arizona.

Winter storms seem more ferocious each year - and they just may be, according to ominous data from the National Oceanic and Atmospheric Administration.

Since 1900, the number of what scientists call extreme precipitation events - blizzards and heavy rainstorms - has jumped 20 percent in the United States.

And the total amount of winter precipitation is up 10 percent, says Thomas Karl, the NOAA climatologist who compiled the data from a century’s worth of rainfall reports.

Climatologists aren’t sure what causes the trend, although it is consistent with computer models that have studied global warming.

Kevin Trenberth of the National Center for Atmospheric Research says the El Nino phenomenon also seems to be changing.

El Nino, a warming of the water in the central Pacific, used to last less than two years. But its most recent appearance lasted five years, from 1990 to 1995.

“We can’t tie that necessarily to global warming, but it does indicate some climate change,” he says.