Climate change will exacerbate the threat of Megadroughts: Scientists

Scientists have warned that Climate change will exacerbate the threat of Megadroughts in report titled Assessing the risk of persistent drought using climate model simulations and paleoclimate data.

This report was published in September 2014 issue of American Meterological Society’s Journal of Climate.

The report is considered as the first to scientifically establish that climate change exacerbates the threat of Megadroughts. This report has taken into consideration of North and South America for its research.

Highlights of report:

• Megadroughts will become considerably more frequent as global warming increases temperatures and reduces rainfall in regions already susceptible. It will lead to severe than the prolonged water shortage.
• Without climate change, there would be a 5 to 15 per cent risk of a megadrought in the south-west of the US this century. But due to climate change, the probability of megadrought jumps to between 20 per cent and 50 per cent, with the southernmost part of the country particularly at risk.
• The threat megadroughts poses is so great that it could decimate the world’s economy and food supply, inflicting a humanitarian crisis.
• Megadroughts have occurred periodically around the world in the past few thousand years. In some cases it had caused civilisations to collapse, such as the ancient Puebloan native-American tribes in the south-west of the US. They abandoned their homes during a megadrought in the late 13th century and the Khmer empire of Cambodia in the 14th century.
• The fallout from future megadroughts will be even more severe because the global population is larger and the strain on water supplies is greater.
• Global warming will make droughts evermore severe and devastating in the future. 
  The south-west of the US, southern Europe, much of Africa, India, Australia and much of Central and South America could all have a drought that lasts decades.
• Scientists warned that the continued global warming could lead to multiple regions experiencing a hot megadroughts at the same time in the future. This could lead to global economic, food and humanitarian shocks.

What is Megadrought?

The term megadrought is generally used to describe the length of a drought.

In scientific literature it is considered as the decades-long droughts or multi-decadal droughts.

Megadroughts historically have been associated with prolonged La Nina conditions, which create cooler than normal water temperatures in the tropical eastern Pacific Ocean.

This reduces evaporation and, in turn, the amount of rainfall.

La Nina, cyclic counterpart to El Nino, consisting of a cooling of surface waters of the Pacific 

Ocean along the western coast of South America.

While its local effects on weather and climate are generally the opposite of those associated with El Nino, its global effects can be more complex.

La Nina events often follow El Nino events, which occur at irregular intervals of about two to seven years.