The last three years of drought in the U.S. West, and particularly in California, have been quite severe. How severe? Well, a new study published last week in the journal of the American Geophysical Union found that the region hasn't experienced condition this severe in at least 1,200 years. That's a while...
Analyzing tree rings that date back to 800 A.D. -- a time when Vikings were marauding Europe and the Chinese were inventing gunpowder -- there is no three-year period when California's rainfall has been as low and its temperatures as hot as they have been from 2012 to 2014, the researchers found.
Meanwhile, some people in California are getting fines because they are not watering their lawn enough...
The scary thing is, nobody can know when it will end. In a different post we quote an expert who said (emphasis mine): "Dr Ingram points to paleo-climate data that correlate the thickness, or absence, of growth-rings in trees with annual precipitation. Such records show California has suffered two droughts over the past 1,200 years that lasted for 120-200 years." So maybe it'll end next year, or maybe it'll last decades. Yikes!
"We were really surprised. We didn't expect this," said one of the study's authors, Daniel Griffin, an assistant professor in the University of Minnesota's department of geography, environment and society.
The data came from 278 blue oak trees. Their tree rings have been analyzed - with wider rings showing more growth in wetter years - and compared to databases of other tree rings. Long-living trees like giant sequoias and bristlecone pines can live centuries, and we have some from 1,200 years back, hence the time range of this study (maybe it's been even longer since a drought of this magnitude, but it's harder to go farther back).
California has received some rain recently, but it's not quite enough yet: "It's a good beginning," said Art Hinojosa, chief of hydrology at the state Department of Water Resources. "But we need storm after storm after storm if we have any hope of getting out of the drought this year."
By April, he said, California needs at least eight more major storm systems like the one this week -- as well as many smaller storms -- to fill its dangerously low reservoirs and break the drought. Rain and snow this winter needs to be at least 150 percent of average for the reservoirs to fill, Hinojosa said. (source)
You can keep track of drought conditions around the US by visiting the US Drought Monitor website.
Via Mercury News