Nearly a quarter of the world’s population is at significant risk from flooding, according to a new study released on Tuesday, which warns that people in poorer countries are more vulnerable.
Flooding from heavy rains and storm surges affects millions of people every year and causes billions of dollars in damage to homes, infrastructure and economies.
And the risks increase as climate change causes more extreme rainfall and sea level rise, as exposed populations swell.
New study, published in the journal Nature Communications, reviewed global data on flood risk from the sea, rivers and rainfall, as well as population distribution and poverty estimates from the World Bank.
It revealed that around 1.81 billion people – or 23% of the world’s population – are directly exposed to flooding greater than 15 centimeters (six inches) during century floods.
“This would pose significant risks to lives and livelihoods, especially to vulnerable population groups,” the study says.
Overall, nearly 90% of people exposed to flooding live in low- and middle-income countries, according to the study.
It also concluded that the number of people living in poverty and at serious risk of flooding is “significantly higher than previously thought”.
The researchers found that some $9.8 trillion of economic activity worldwide – about 12% of global gross domestic product in 2020 – is in areas prone to severe flooding.
But they said simply focusing on a monetary value could lead to a bias in attention towards high-income countries and economic hubs.
“Adjusting the poverty levels of exposed populations, we show that low-income countries are disproportionately exposed to flood risk, while being more vulnerable to disastrous long-term impacts,” the study said. World Bank’s Jun Rentschler and colleagues.
Overall, the study estimates that most people at risk from flooding – 1.24 billion – are in South and East Asia, with China and India accounting for more than a third of the global total .
Some 780 million people living on less than $5.50 a day are at risk from floods that occur once every hundred years, he found.
The research provides “the first global estimates of the interaction between exposure to flood risk and poverty,” said Thomas McDermott, of the National University of Ireland, Galway, in a linked comment published in Nature Communications. .
The authors said previous studies were often limited by geography or the type of flood risk assessed and had underestimated the number of people exposed globally.
“Climate change and risky urbanization patterns are expected to further aggravate these risks in the years to come,” they added.
According to World Weather Attribution, a network of scientists tracking the impacts of climate change, global warming has made extreme rainfall events more common and more intense across most of the world.
This likely worsened flooding in these areas, although scientists point out that other human factors also play a role, such as decisions about where to locate homes and infrastructure.
This month, record flooding in southern China displaced more than half a million people.
In Bangladesh, the Red Cross said on Tuesday that seven million people were still in “desperate” need of shelter and aid after some of the heaviest rains in a century caused rivers to swell to record levels and flooded rural villages.