Rising temperatures and human activity are increasing storm runoff and flash floods

Researchers have demonstrated for the first time that runoff extremes have been dramatically increasing in response to climate and human-induced changes. Their findings show a large increase in both precipitation and runoff extremes driven by both human activity and climate change. They also found that storm runoff has a stronger response than precipitation to human-induced changes (climate change, land-use land-cover changes, etc).

The researchers discovered that changes in storm runoff extremes in most regions of the world are in line with or higher than those of precipitation extremes. They noted that different responses of precipitation and storm runoff to temperature can be attributed not only to warming, but also to factors like land-use and land-cover changes, water and land management, and vegetation changes that have altered the underlying surface conditions and hydrological feedbacks that have, in turn, increased storm runoff.

Precipitation is generated after water vapour condenses in the atmosphere, and precipitation intensity is governed by the availability of atmospheric water vapour. Because the atmosphere can hold more moisture as temperature rises, climate scientists expect to see an intensification of precipitation extremes with climate change.