Friday, August 2, 2013

Hot topic: Wet and dry seasons shifting over U.S.

Here's another climate story from LiveScience that I used in Overnight News Digest: Science Saturday (the cost of Arctic thawing) on Daily Kos last Saturday night.

Weird Weather: Dry Seasons Start Earlier, Are Wetter
By Becky Oskin, Staff Writer
July 25, 2013 10:36am ET
Call it weird, call it extreme, maybe even call it the new normal. Wild weather in the United States in the past decade has amassed a long list of toppled records and financial disasters.

Some of these exceptional weather events included unusually heavy rain and snow. Now, a new study confirms that everywhere except in the Atlantic Plains region, more rain and snow is falling during wet and dry seasons alike. The Atlantic Plains are the flatlands along the central and southern Atlantic Coast that stretch from Massachusetts to Mississippi. On average, the total precipitation in the contiguous United States has increased 5.9 percent, according to the U.S. Environmental Protection Agency.

What's more, the timing has changed too. In some parts of the United States, dry seasons are arriving earlier and wet seasons are starting later than they did 80 years ago. The time shift does not necessarily extend the length of dry or wet seasons, because most areas have transitional periods in between these precipitation extremes.  In the Ohio River Valley, the fall dry season starts two to three weeks earlier today, the researchers report. In east New York, the wet season now kicks off on Jan. 8 instead of Feb. 1. And in the Southwest, the summer monsoon is starting later than it did during the middle of the 20th century.
Welcome to the 400 ppm world.

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