Drought: the new norm?

A new study published in Nature-Geoscience suggests that drought in the western U.S. between 2000 and 2004 may have been the worst in nearly a millennium, depleting water resources and causing significant declines in river flows and crop yields.

There is yet another effect. Plants grown in North America do a good job absorbing carbon dioxide from the atmosphere, offsetting carbon emissions.

"Our study shows the turn-of-the-century drought reduced plant uptake by half in western North America," said Kevin Schaefer of the National Snow and Ice Data Center, one of the authors.

Drought in the American Northwest may "trigger a whole host of significant water resource challenges in a region already subject to frequent water shortages," Schaefer said.

From long-term imponderables back to short-term action. A further surge in commodity prices may lead the G-20 to convene its Rapid Response Forum within the next month in an effort to prevent the bottlenecks in 2007 and 2008 that led to food riots.

Buyers -- and insurance underwriters -- await the next U.S. Agriculture Department crop report due Wednesday with trepidation. The insurance bill from the subpar crops on American farms this year probably exceeds $18 billion, according to underwriters.

There are already ominous signs: Last week, the price of soybeans was close to 1,800 cents per bushel (up from about 1,300 cents in June) as Brazilian exports sagged. And in a sign that some buyers are worried grain supplies may tighten, one Mexican buyer last month made the fourth largest single purchase of U.S. corn since 1991, according to the Financial Times.

There's also demand for corn from ethanol producers, now that U.S. gasoline is not far shy of $4 a gallon.

If Russia were to introduce a grain export ban, as it did in 2010 to restrain prices at home, global prices would probably accelerate. In the face of market forces, the G-20 has few tools.

In the meantime, there are always silver linings amid the dark warnings. Here are two. Drought in the Midwest has sharply reduced the runoff of nitrates into the Mississippi River and down into the Gulf of Mexico. As a result, the "dead zone" of algae bloom has shrunk dramatically to an estimated 1,580 square miles, from about 3,400 square miles a year ago.

One of the photographs in a recent Atlantic gallery shows the enterprising Joseph Perazzo of Grass is Greener Lawn Painting turning a parched lawn in New Jersey into a picture of emerald green.

"Miracle Results" proclaims his sign. Maybe that's what we need.