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WATER POLITICS

Via UCAR, an interesting look at a new study from the National Center for Atmospheric Research which starkly lays out how droughts, some so extreme that they are nearly without precedent, may spread throughout many of the world’s most densely populated places by the end of the 21st century. Here’s where it could get devastatingly dry:

images: University Corporation for Atmospheric Research

The colors above represent difference levels of the Palmer Drought Severity Index. Positive numbers are when conditions are unusually wet for a region; negative numbers indicate unusual dryness. A reading of -4 is considered extreme drought. Current readings range from +10 to -10, with readings below -6 occurring only very rarely. Keep in mind that the above maps shouldn’t be viewed as hard forecasts, as the actual rise in greenhouse gas emissions as well as natural climatic variations could alter drought patterns.

Only Small Pockets of Globe Experience Little Change in Precipitation
As you can see, by 2030 all of the United States save for the mid-Atlantic States and the Northeast could be in for much, much drier conditions, and under a business-as-usual emissions scenario only New England is spared drought conditions. By 2100, parts of the US could see readings in the -8 to -10 range.

Across the globe much of Latin America, the areas around the Mediterranean Sea, large areas of Southeast and Southwest Asia, Australia, and much of Africa experience extreme drought. By century’s end the Mediterranean could see PDSI readings of -15 to -20. Conversely, Northern Europe, Russia, Canada, and Alaska experience conditions wetter than today.

A few pockets of normal to slightly wetter conditions occur in Argentina, the Horn of Africa, South Asia and East Asia.

Consequences of Climate Change Caused Drought Enormous
Study scientist Aiguo Dai says, “We are facing the possibility of widespread drought in the coming decades, but this has yet to be fully recognized by both the public and the climate research community. If the projections in the study come even close to be realized, the consequences for society worldwide will be enormous.”

On the increased wetness in certain areas, Dai notes, “The increased wetness over the northern, sparsely populated high latitudes can’t match the drying over the more densely populated temperate and tropical areas.”