While this winter’s outlook is based upon La Niña’s influence, the National Center for Atmospheric Research, in a paper reviewing recent literature on drought, contends that the U.S. and many other heavily populated countries face a growing threat of severe, prolonged drought in coming decades.

The analysis of 22 computer climate models and previously published studies by NCAR scientist Aiguo Dai projects that warming temperatures will bring increasingly dry conditions over much of the earth over the next three decades — perhaps on a scale not seen in modern times.

In just 20 years, vast areas of the world are going to be far drier than they are today, the study says.

“A striking feature is that aridity has increased since the late 20th century and will become severe drought by the 2060s over much of the Americas, southeast Asia, the Middle East, Africa, Australia, and southern Europe.”

Areas where drought is expected to decrease include much of northern Europe, Russia, Canada, Alaska, and some areas in the southern hemisphere.

But, Dai says, “the increased wetness over the northern, sparsely populated high latitudes can’t match the drying over the more densely populated temperate and tropical areas.

“If the projections in this study come even close to being realized, the consequences for society worldwide will be enormous.”

A previous study by Dai and his colleagues found that the percentage of Earth’s land areas affected by serious drought more than doubled in the period from the 1970s to the early 2000s, and that some of the world’s major rivers are losing water.

By the 2030s, Dai’s study indicates, some regions in the U.S. and overseas could be experiencing “particularly severe” drought conditions.

While he cautions that his findings are based on the best current projections, “what actually happens in coming decades will depend on many factors, including actual future emissions of greenhouse gases and natural climate cycles such as El Niño.”