California's seen plenty of droughts, but it's been awhile since they were this dry.
Awhile as in 12 centuries, a new study co-authored by a University of Minnesota scientist finds.
Daniel Griffin, an assistant professor at the U of M, worked with a colleague from Woods Hole Oceanographic Institute in measuring tree rings to determine how dry the soil is in central and southern California during the current three-year drought.
They found that, while there have been other periods with even less rain and snow, the current moisture shortage has combined with record-breaking heat to make this the worst drought on record in the Golden State.
The study conducted for the American Geophysical Union compared rings from blue oak trees now growing in California to a database of tree ring information that dates back 1,200 years.
Live Science reports Griffin says because today's dryness results from heat as well as lack of rain, "this drought is a harbinger of what we can expect in the future" as climate change raises temperatures in the West.
But a separate study released on the heels of Griffin's work finds California's drought is not driven by a buildup of greenhouse gases.
The research sponsored by the National Oceanic and Atmospheric Administration attributes the drought to natural patterns, specifically a high-pressure ridge off the Pacific coast that kept storms from reaching California in three straight rainy seasons.
Griffin's co-author, Kevin Anchukaitas, tells the Washington Post their research looked at the severity of the current drought, not its causes, so it does not conflict with the NOAA study. The Post says both studies note that rising temperatures may worsen future droughts.
Rains that fell on California last week amounted to a drop in the bucket compared to what it will take to alleviate the drought. But forecasters say another round of storms is headed toward the state this week.