Unless governments urgently boost their flood defenses, millions of people across the world will be at risk from river flooding in the next 20 years, scientists said on Wednesday.
As global warming increases, likelihood of severe rainfall would also rise, says a study published in the journal Science Advances. Researchers said Pakistan, which is already prone to flooding, “will observe almost a doubling in high-end flood risk,” with 11 million people at risk of floods unless protective measures are taken by 2040.
The study notes, “Historically, Pakistan is already highly affected and will observe almost a doubling in high-end flood risk on a subnational level, from 6 million to 11 million people without additional protection. All of its provinces are already affected in the historic period. Most affected are the eastern provinces, Punjab and Sind, which will need an increase in protection.”
A similarly strong flood risk was seen in 26 of India’s 36 states and union territories, three of which exceed 1 million people. “Most affected is the province of Bihar,” the study said.
Unless actions are taken — such as enhancing dykes, boosting building standards, relocating settlements and managing rivers — the number of people affected by devastating floods could skyrocket, warns the report. The study is based on models 10 times more precise than commonly used climate computer simulations.
Read more: Pakistan at Risk
Asia would get hit the hardest, with the number of people affected by flooding projected to go from 70 to 156 million by 2040, it said.
“China will observe an increased high-end flood risk from 24 million to 55 million affected people. All but Shanghai show an increase in high-end risk of at least 20%; 14 of 31 provinces will have more than a million people under high-end risk. Even the comparably strongly protected Hubei will face a 10-fold increase if the protection is not increased. The most affected regions are close to Shanghai, which itself is not affected by river flood (currently protected against 200-year floods). Guangdong, the province surrounding Hong Kong, is heavily affected and shows a massive increase from 0.7 million to 3.8 million people. Hong Kong itself is not expected to show an increase in high-end risk.”
“In South America the number of people affected by flooding risks will likely increase from six to 12m, in Africa from 25 to 34m,” it added.
In Germany the number of people affected is projected to rise sevenfold, from 100,000 to 700,000.
In North America, it could rise from 100,000 to one million.
“More than half of the United States must at least double their protection level within the next two decades if they want to avoid a dramatic increase in river flood risks,” said lead author Sven Willner from the Potsdam Institute for Climate Impact Research.
The increase in river flood risks over the next few decades is being driven by the amount of greenhouse gases already emitted into the atmosphere by the burning of fossil fuels.
When more heat-trapping pollutants surround the Earth, more moisture is held in the air, leading to more rainfall.
Cutting these emissions is crucial to reducing flood risks for future generations. “Global warming increases the risk of flooding because the amount of rain that can fall during an extreme downpour increases exponentially as temperatures rise,” said Anders Levermann, a co-author of the study in an interview.
“These findings should be a warning to decision-makers,” added Levermann. “Doing nothing will be dangerous.”
Read the full report here