More evidence links global warming with extreme rainfall

Rainfall intensity to increase 7 percent with every degree of global warming

Summer thunderstorms are likely to become more intense in a warming world.

By Summit Voice

SUMMIT COUNTY — Climate scientists have long said that a warming Earth will result in more intense rainstorms. Warmer air holds more moisture, and the additional thermal energy in the atmosphere can stir up more storms.

New empirical evidence supports those ideas, including a worldwide review of global rainfall data led by the University of Adelaide, which found that the intensity of the most extreme rainfall events is increasing across the globe as temperatures rise.

The scientists said it’s one of the most comprehensive review of changes to extreme rainfall ever undertaken. The study looked at the association between extreme rainfall and atmospheric temperatures at more than 8000 weather gauging stations around the world.

“The results are that rainfall extremes are increasing on average globally. They show that there is a 7 percent increase in extreme rainfall intensity for every degree increase in global atmospheric temperature,” said lead author Dr Seth Westra.

“Assuming an increase in global average temperature by 3 to 5 degrees Celsius by the end of the 21st century, this could mean very substantial increases in rainfall intensity as a result of climate change.”

Westra, a senior lecturer with the University of Adelaide’s School of Civil, Environmental and Mining Engineering and member of the Environment Institute, said trends in rainfall extremes were examined over the period from 1900 to 2009 to determine whether they were becoming more intense or occurring more frequently.

“The results show that rainfall extremes were increasing over this period, and appear to be linked to the increase in global temperature of nearly a degree which also took place over this time.

“If extreme rainfall events continue to intensify, we can expect to see floods occurring more frequently around the world.” Westra said.

The strongest increases occurred in the tropical countries, although some level of increase seems to be taking place at the majority of weather gauging stations.

“Most of these tropical countries are very poor and thus not well placed to adapt to the increased risk of flooding, which puts them in a larger threat of devastation.”


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