Higher CO2 levels could lead to more summer floods

Rising levels of carbon dioxide in the atmosphere will lead to higher river levels and an increase in the risk of summertime flooding because plants will be less able to soak up rainwater from waterlogged soil, the Met Office has found.

The research reveals a significant link between rising CO2 levels caused by burning fossil fuels and the ability of plants to absorb water through their roots – a major factor that prevents saturation of the soil during wet summers. Met Office scientists said that a computer analysis of how the effect will influence river levels around the world has found that there will be costs as well as benefits.

Droughts may be less severe than anticipated in some regions, but the risk of flooding in high-rainfall areas could increase significantly.

"It's a double-edged sword. It means that increases in drought due to climate change could be less severe as plants lose less water," said Richard Betts, a computer modeller at the Met Office Hadley Centre in Exeter, who led the study. "On the other hand, if the land is saturated more often you might expect that intense rainfall events are more likely to cause flooding."