Over 300 million people in coastal regions risk being homeless by 2050, thanks to rising sea levels, says study
In the US, nearly 40% live in coastal areas, and if emissions go unchecked, a large majority of Americans will be impacted by coastal flooding.
Coastal floods due to rising sea levels are already here and it is about to get worse. According to the latest estimates, 300 million people living in coastal regions around the world could risk losing their homes and livelihood by 2050.
And if human emissions go unchecked through 2100, the risk could be doubled, affecting 630 million lives, according to a study.
In the US, for example, 40% of the population currently live in coastal areas, and this number is expected to rise in the future. If emissions go unchecked, a large majority of Americans will be impacted by sea-level rise and coastal flooding, says the research team.
According to the researchers, led by Climate Central, an independent group of scientists, these projections are more than three times higher than previous estimates, which was calculated using satellite data.
Sea-level rise is not new, the levels have been on the rise in the last century, picking up an accelerated pace in the last few decades. And for this, we have human activity-induced emissions to blame, says the research team.
More than 90% of heat released from human emissions find their way into the oceans, where they are absorbed. When this happens, water expands and rises. Another factor contributing to sea-level rise is the melting of land ice such as glaciers and ice sheets in Antarctica or Greenland.
To keep a check on the changing sea levels, most scientists use NASA’s Shuttle Radar Topography Mission, which provides them with satellite information. But the duo of Scott Kulp and Benjamin Strauss from Climate Central, authors of the study, noticed a flaw with the satellite data. According to them, it overestimated the height of the land due to tall buildings and trees.
The research team corrected this discrepancy by mapping the actual height of the ground those buildings sat on, instead. "We have elucidated that you can't measure flood risk by analyzing the elevation of rooftops – you have to know the height of the ground beneath your feet," Strauss told Business Insider.
The model allowed them to peek into the future sea levels. In a highly optimistic scenario, where greenhouse-gas emissions peak in 2020 and then decrease, they predict that 190 million people will occupy land below sea level by the end of the century.
The researchers say in the worst-case scenario, where emissions continue to rise through 2100, that number could reach 630 million people, globally.
“If our findings stand, coastal communities worldwide must prepare themselves for much more difficult future than currently anticipated,” the scientists said.
Future impacts in different countries
If the estimates turn into a reality in the future, then sea-level rise in the US may force people to migrate out of coastal regions and into the inland regions, putting higher pressure on the latter.
But Asia will be more severely affected, with Indonesia already reeling under intense coastal flooding, the study finds. The model found that by 2050, 237 million people in China, Bangladesh, India, Vietnam, Indonesia, and Thailand could face annual coastal flooding threats every year. The number could jump to 250 million by 2100 if emissions continue unchecked.
“As the tideline rises higher than the ground people call home, nations will increasingly confront questions about whether, how much and how long coastal defenses can protect them,” Kulp told the Guardian.
Strauss hopes that countries will take note of the study and ramp up their efforts to address the issue. "Even as we show there's a far greater threat from sea-level rise, we now know that there are far greater benefits to cutting emissions. This new data can be a useful tool for cities and countries to plan better for the future their coastal populations are facing," Strauss told Business Insider.