India faces risk of annual coastal flooding: Study

A new research study has projected that 36 million people in India could face annual coastal flooding by 2050 if global CO2 emissions are not cut drastically. The findings are based on CoastalDEM, a new digital elevation model developed by Climate Central, a US based climate research and communications organisation.

According to Climate Central, coastal flood risks assessments were until now based on NASA’s Shuttle Radar Topography Mission (SRTM) but it underestimated the elevation risks according to the study published in the journal, Nature Communications.

SRTM measured elevation of surfaces closest to the sky such as tree tops and rooftops wherever they blocked the ground. CoastalDEM reduces these errors. For instance, based on SRTM data, only 5 million people in India were expected to face coastal flooding by 2050. The study also states that coastal flooding could affect 300 million people globally by 2050 and high tide lines could permanently rise above land occupied by some 150 million people, mostly in Asia.

“Estimates based on unchecked emissions (not meeting the 2015 Paris Agreement) and the potential for early-onset ice sheet instability project that sea level rise could threaten areas where as many as 640 million people now live — 340 million of whom are on land forecast to fall below the high tide line by 2100. In eight Asian countries, that scenario means regular high tides would be higher than land currently home to at least 10 million people,” Climate Central said in a statement on Tuesday.

Global mean sea level rose by 11-16 cm in the 20th century. Even with sharp, immediate cuts to carbon emissions, it could rise another 0.5m this century. But the study warns that under higher emissions scenarios, 21st century rise may exceed 2m in the case of early-onset Antarctic ice sheet instability.

Bangladesh and China would face worse impacts. The new data suggests about 93 and 42 million people in China and Bangladesh respectively are likely to be affected by severe coastal flooding by 2050.