As CO2 levels in the atmosphere increase, plants uptake less water from the soil. Betts’ model indicates that there could be a 6 percentage point increase due to this effect on top of the 11% increase in global water flows due to direct climate effects.
Researchers say efforts to calculate flooding risk from climate change do not take into account the effect carbon dioxide (CO2) has on vegetation. Higher atmospheric levels of this greenhouse gas reduce the ability of plants to suck water out of the ground and “breathe” out the excess. Plants expel excess water through tiny pores, or stomata, in their leaves. Their reduced ability to release water back into the atmosphere will result in the ground becoming saturated.
Feedbacks, always a problem and hard to predict.