Sunday 26 August 2012

The Great American Drought

Western North America drought is worst in 800 years, study says

24 August, 2012

A new scientific study indicates the turn-of-the-century drought in the North American West was the worst of the last millennium—with major impacts to the carbon cycle and hints of even drier times ahead.

The study, titled “Reduction in carbon uptake during turn of the century drought in western North America,” indicates that the major drought that struck western North America from 2000 to 2004 severely reduced carbon uptake and stressed the region's water resources, with significant declines in river flows and crop yields. It was published on July 29 in Nature-Geoscience. NSIDC scientist Kevin Schaefer is a co-author on the study, along with Christopher Williams of Clark University. The study was led by Christopher Schwalm of Northern Arizona University (NAU).

Researchers found that the turn-of-the-century drought was the most severe region-wide event of its kind since the last mega drought 800 years ago. “The turn-of-the-century drought may be the wetter end of a new climatology that would make the 21st century climate like mega-droughts of the last millennium,” said Schwalm.

Under normal climate conditions North America absorbs carbon dioxide from the atmosphere due to plant growth, offsetting to anthropogenic carbon emissions from the burning of fossil fuels. "Our study shows the turn-of-the-century drought reduced plant uptake by half in western North America," said Schaefer.

The current drought that has currently engulfed country is as intense in the western United States as the turn of the century drought, but also includes large portions of the Midwest and Eastern United States.

Climate models indicate drought conditions in the American West may be the new normal as the planet warms, expanding the region that is already chronically dry. “This will not only reduce carbon uptake,” says Schaefer, “but will also would trigger a whole host of significant water resource challenges in a region already subject to frequent water shortages.”

The study was supported by the National Science Foundation (NSF).

Image of the Day: Satellite view of thick smoke from wildfires over Wyoming, 14 August 2012

24 August, 2012

Wildfires in California, Oregon, Idaho, and Nevada sent smoke over large stretches of the United States in mid-August 2012. Particularly thick smoke collected over Wyoming on August 14, when the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image. Smoke filled the skies over most of the state; over the south-central part of the state, it was thick enough to completely hide the land surface below.

Although smoke appeared especially thick over Wyoming, air quality suffered across the United States. The “Smog Blog” at the University of Maryland-Baltimore County reported that smoke plumes stretched from northern California eastward to Nebraska. Plumes also extended over the Upper Midwest and northward into Canada. Over the westernmost United States, smoke mixed with ozone, prompting numerous air-quality alerts, Smog Blog reported.

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