Carbon emissions up risk of US megadroughts

Human-produced greenhouse gas emissions drives up the risk of severe droughts, shows a new study carried out in the US.

Droughts in the US during the last half of this century could be drier and longer than drought conditions seen in those regions in the last 1,000 years.

The study is based on projections from several climate models, including one sponsored by NASA.

"Natural droughts like the 1930s Dust Bowl and the current drought in the Southwest have historically lasted maybe a decade or a little less," said Ben Cook, climate scientist at NASA's Goddard Institute for Space Studies and lead author.

"What these results are saying is we are going to get a drought similar to those events, but it is probably going to last at least 30 to 35 years," Cook noted.

The current likelihood of a megadrought, a drought lasting more than three decades, is 12 percent.

If greenhouse gas emissions stop increasing in the mid-21st century, the likelihood of megadrought to reach is more than 60 percent.

But, if greenhouse gas emissions continue to increase along current pace, there is an 80-percent likelihood of a decades-long megadrought between the years 2050 and 2099.

"What I think really stands out in the paper is the consistency between different metrics of soil moisture and the findings across all the different climate models," said Kevin Anchukaitis, climate scientist at Woods Hole Oceanographic Institution, Massachusetts.

This study is also the first to compare future drought projections directly to drought records from the last 1,000 years.

"These findings require us to think about how we would adapt if even more severe droughts lasting over a decade were to occur in our future," Anchukaitis concluded.

The study appeared in the journal Science Advances.