Rising emissions could ‘dramatically’ increase risk of US megadroughts

Increasing greenhouse gas emissions drive up the risk of severe droughts, or megadroughts, in the US southwest and central plains, according to a study by NASA.

According to the research, which has been published in the journal Science Advances, the current likelihood of a megadrought, defined as a drought lasting more than three decades, is 12%. If greenhouse gas emissions stop increasing by mid-century the findings suggest the likelihood of a megadrought could reach more than 60%.

If the world fails to slow emissions over the next 35 years and greenhouse gas emissions continue to increase along current trajectories throughout this century the risk of a drought lasting decades between 2050 and 2099 rises further to 80%.

Ben Cook, climate scientist at Nasa’s Goddard Institute for Space Studies and Columbia University, who led the study, said, “Natural droughts like the 1930s dust bowl and the current drought in the southwest have historically lasted maybe a decade of a little less. What the results are saying is we’re going to get a drought similar to those events, but it is probably going to last at least 30 to 35 years.”

Researchers used 17 different climate models for each of the emissions scenarios, the findings suggest that if greenhouse gas emissions continue to rise, so will the threat of prolonged drought.

The study also compared the findings to megadroughts that took place between 1100 and 1300 in North America. These medieval droughts were similar to droughts in recent years but lasted much longer. However, in both the moderate and business-as-usual emissions scenario’s of the study the future is predicated to be drier with the risk of such an event significantly higher.

Climate scientist Kevin Anchukaitis, from the Woods Hole Oceanographic Institute, who was not involved in the study, commented, “Those droughts had profound ramifications living in North America at the time. 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.”

Photo: Anthony Quintano via Flickr

Further reading:

80% of California in ‘extreme drought’, scientists warn

Climate change worsening California drought

How does climate change affect the strength and frequency of floods, droughts, hurricanes, and tornadoes?

Scientists say climate change not to blame for 2012 US drought

Climate change creating ‘water crisis’ in Australia