People who live far away from coastal areas could still be affected by floods caused by climate change due to changes in rivers, according to a study.
Researchers analysed flooding and rivers in the northeast Gulf of Mexico and found that rivers play a large, and overlooked, role in flooding.
Scientists at the University of South Carolina showed that climate change has resulted in larger amounts of precipitation moving faster downstream to the coast through rivers.
This results in more river flooding and a greater likelihood of 'compound flooding' – a flood where ocean storm surge mixes with river discharge.
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Compound flooding events are largest inland, where tides become small and disappear.
The researchers warned that this phenomenon put people who lived near inland rivers in danger.
Coastal flooding will likely increase as the climate continues to warm and intensify precipitation.
Steve Dykstra, a post-doctoral research fellow at the School of the Earth, Ocean and Environment, warned that the warming atmosphere can hold more water and causes more intense precipitation.
The research shows that this affects entire watersheds down to the coast, a region where river floods were previously thought to play a minor role.
"People who study oceans stop where there is salt. People who study rivers stop where there is a tide, sometimes 200 miles inland," Dykstra said. "We're missing the other side of the puzzle."
He added: "Scientists and policymakers need to account for rivers when talking about coastal flooding. Data sets used to track river processes need to extend over significant lengths of time.
"Researchers need to account for changes over time to understand flood risks. Scientists need to use this new insight to better identify the highest risks for compound flooding."
This year’s UN climate change report warned that extreme weather events like heatwaves and droughts that previously would have happened every 50 years could soon happen every four.
The report pointed out that Europe was already seeing the effects of climate change, with extreme droughts affecting the Mediterranean region.
But in the coming years, the report predicted that events such as this summer’s flooding in Germany, and wildfires in Greece, could continue, or worsen.
The report predicted, with high confidence, that droughts and 'fire weather' in the Mediterranean region would continue. Meanwhile in northern Europe, river flooding would get worse.
Both of these have been caused by human contribution to climate change, the researchers said.
Snow and ice in the Alps will decrease below elevations of 1500 metres throughout the 21st century, and glacier ice will retreat in the Alps and Scandinavia.
'Periglacial' processes in northern Europe, where areas near a glacier or ice sheet thaw and refreeze, will stop altogether by 2100.
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