Global warming, human activities causing increased storm runoff, flash floods

0

  • A new study published in the journal Nature Communications this week looks at how storm runoff levels might respond to future changes in surface temperature and atmospheric moisture content driven by both natural causes and human activities.
  • The research team behind the study, led by Pierre Gentine, an associate professor of earth and environmental engineering at Columbia University in New York City, says that there’s is the first global analysis to show that storm runoff extremes are rising sharply in response to climate and human-induced changes — and that the magnitude of storm runoff is likely to continue increasing in most regions at rates substantially higher than projected by previous climate models.
  • Gentile and team argue that there is “an urgent need” to increase human society’s resilience to both climate change and the changing environment, because storm runoff extremes are intensifying as the world warms and our existing infrastructure systems may not be able to cope.

According to a report by the UN Office for Disaster Risk Reduction and the Centre for Research on the Epidemiology of Disasters, climate-related catastrophes like droughts, floods, and other extreme-weather events accounted for more than 90 percent of the 7,255 disasters recorded over the past 20 years, which collectively killed 1.3 million people and left 4.4 billion more either injured, homeless, or displaced.

Of those climate-related disasters, 43 percent were flash floods, one of the leading causes of deaths and economic damages driven by severe weather events around the world. A 2017 study found that floods have been responsible for an average of $30 billion in economic damages every year for the past decade. And as global temperatures continue to rise and the impacts of human activities accelerate, increasing numbers of extreme precipitation events are expected to make flash flooding even more frequent and costly.

A study published in the journal Nature Communications last week looks at how storm runoff levels might respond to future changes in surface temperature and atmospheric moisture content driven by both natural causes and human activities. The research team behind the study, led by Pierre Gentine, an associate professor of earth and environmental engineering at Columbia University in New York City, says that there’s is the first global analysis to show that storm runoff extremes are rising sharply in response to climate and human-induced changes — and that the magnitude of storm runoff is likely to continue increasing in most regions at rates substantially higher than previously projected by climate models.

Jiabo Yin of China’s Wuhan University, the study’s lead author, is currently a visiting student at Columbia University in New York City, where he’s working with Gentine’s research group. He says the team performed a global-scale hydrological analysis in order to determine what physical mechanisms are driving increasing extreme precipitation and runoff events.

“We know that precipitation and runoff extremes will significantly intensify in the future, and we need to modify our infrastructures accordingly,” Yin said in a statement. “Our study establishes a framework for investigating the runoff response.”

After determining the mechanisms driving increased precipitation and runoff, the researchers systematically compared runoff rates and temperatures over the past several decades to precipitation levels across the globe. They found that changes in storm runoff extremes in most of the world are in line with or in some cases even higher than those of precipitation extremes.

Because a warmer atmosphere can hold more moisture, and precipitation is the result of atmospheric water vapor condensing, climate scientists have long projected more intense precipitation extremes due to global warming. But Yin, Gentine, and team determined that storm runoff rates will have an even more dramatic response than precipitation to human-induced pressures like climate change and land-use changes such as deforestation, posing potentially severe threats to ecosystems and communities.

“These strong responses imply that more attention should be paid to the potentially underestimated response of storm runoff to climate and anthropogenic changes in order to improve our understanding and projection of flash flooding events and to improve community resilience,” the researchers write in the study.

Gentile and team argue that there is “an urgent need” to increase human society’s resilience to both climate change and the changing environment, because storm runoff extremes are intensifying as the world warms and our existing infrastructure systems may not be able to cope.

“Our work helps explain the underlying physical mechanisms related to the intensification of precipitation and runoff extremes,” Gentine said in a statement. “This will help improve flood forecasting and early-warning alerts. Our findings can help provide scientific guidance for infrastructure and ecosystem resilience planning, and could help formulate strategies for tackling climate change.”

Columbia Engineers lead first global analysis to characterize the responses of storm runoff extremes to climate and human-induced changes; study sheds new light on rising magnitude of extreme flash floods. Photo Credit: Eric Buermeyer/Shutterstock.

CITATION

• Roxy, M. K., Ghosh, S., Pathak, A., Athulya, R., Mujumdar, M., Murtugudde, R., … & Rajeevan, M. (2017). A threefold rise in widespread extreme rain events over central India. Nature Communications, 8(1), 708. doi:10.1038/nclimate1911

• Yin, J., Gentine, P., Zhou, S., Sullivan, S.C., Wang, R., Zhang, Y., & Guo, S. (2018). Large increase in global storm runoff extremes driven by climate and anthropogenic changes. Nature Communications 9. doi:10.1038/s41467-018-06765-2

This story first appeared on Mongabay

South Africa Today – Environment


This article is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International License.

You may republish this article, so long as you credit the authors and Mongabay, and do not change the text. Please include a link back to the original article.

Disclaimer: The views of authors published on South Africa Today are their own and do not necessarily represent the views of South Africa Today. By viewing, visiting, using, or interacting with SouthAfricaToday.net, you are agreeing to all the provisions of the Terms of Use Policy and the Privacy Policy.