When did the drought in California begin?

US West Coast water shortage : California is experiencing the worst drought in 1200 years

The water shortage keeps California under control. Meteorologists are expecting more precipitation in winter than in the past few months, but they will not solve the problem. Current simulations by the NOAA weather agency suggest that the drought will continue in large parts of the state in the next year. It began in 2012 and is one of the heaviest in history, researchers at the Woods Hole Oceanographic Institution report. Among other things, they analyzed tree rings from blue oaks, according to which it is the worst drought in California for 1200 years, they write in the "Geophysical Research Letters".

Satellite tandem detects water loss

The water levels in the reservoirs have sunk massively, and far more is extracted from the groundwater than is replenished by precipitation. As Nasa reported on Tuesday, 42 cubic kilometers of water are needed to compensate for the loss in the country. The calculation is based on measurements of the two “Grace” satellites (Gravity Recovery and Climate Experiment), which were developed by Germany and the USA. They orbit the earth and register minimal changes in the gravity, which in turn indicates ice or water loss.

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The drought is extreme but not uncommon

The drought has natural causes, write Richard Seager of Columbia University in New York and colleagues in a report for NOAA. Higher temperatures as a result of global warming would only have a small share. "The drought in California is extreme, but not unusual for the state," says Seager. Periods of several years with little precipitation would occur regularly. According to the researchers, as a result of a certain temperature distribution in the Pacific, a "high pressure ridge" has formed over the ocean, which stops winter storms that normally bring abundant rainfall to the coastal region.

The climate researcher Michael Mann of the Pennsylvania State University criticizes the study. They clearly underestimate the contribution of man-made global warming, he writes in the "Huffington Post".

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