More than 400 million global citizens living close to the sea will be at risk by 2100 if the sea level continues to rise due to climatic changes. This could happen if the process to reduce global emissions doesn’t start now.

At present, over 267 million people live on land less than 2 metres above sea level, according to a paper published in Nature Communications. Rising sea levels could directly threaten their livelihood. And Indonesia faces the maximum possible risk, as per a study using a new elevation data model for accuracy.

Data analysis from the study indicates a sea-level rise of 1 metre, which is likely by 2100. This means more than 500,000 sq. km. of land could go below mean sea level.

In a first-of-its-kind study, researchers used a remote sensing method called Lidar, which leveraged laser light across coastal areas to measure elevation on the earth’s surface.

The tropics would account for 62 percent of the “most at-risk land” in the future, as per the images of the maps captured by the researchers. And 62 percent of the world’s population living in the tropics, including 52 percent living in Asia’s tropical regions, would face the risk in the future.

According to the lead author of the study, Dr Aljosja Hooijer, water resources expert for Deltares, an independent institute for applied research in water and subsurface and the National University of Singapore said:

"The tropical regions needed more focussed effort to prevent a long-term flood. He specifically mentioned regions in southeast Asia, the Niger Delta, and Lagos."

The authors highlighted an immediate requirement of adaptation measures and spatial planning for long-term flood risk prevention.

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Some countries have taken measures as seen in the case of Bangladesh. It has deployed evacuation techniques to reduce casualties from over a hundred thousand people in the 1970s to about 120 in the case of super-cyclone Amphan in 2020.

Researchers suggest that new data would help policymakers and experts in finding the location of vulnerable areas.

Researchers in the Netherlands or parts of the UK and the US use Lidar every four years and have data for their coastal zones.

The 2100 projection assumed zero population growth and sea-level rise of one meter (approximately 3.3 feet) by 2100.

Climate emergency can be expected due to the frequent rise in sea levels. This could cause severe storms more frequently; thereby increasing flood risks in the coastal areas.

Coastal cities need to prepare for 5-metre high sea levels by 2300, said 106 researchers in their survey published in Climate and Atmospheric Science (2020).

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First Published:Jul 2, 2021 6:19 PM IST