Climate change is likely to threaten 55 million people in India’s coastal areas and could lock in enough sea level rise to submerge land currently home to more than half a billion people globally if the temperature rises by 4 degrees Celsius.  Mumbai and Kolkata are among the top 10 megacities across the world that face a serious threat due to rising sea levels owing to climate change, according to a report released on 9 November by Climate Central, a US-based non-profit research journalism organization.

It warned that a 4°C increase in temperature could submerge a whopping 145 million in China alone and as many as 11 million people are at risk in Mumbai alone if the global temperature rises by 4°C, said the report.

The findings came just weeks ahead of a UN climate summit to be held in Paris from November 30 to December 11. The objective of the summit is to cap the rise in Earth’s temperatures to 2°C above pre-industrial levels, and this remains a serious challenge.

The report said that carbon emissions, causing 4°C of warming, could result into rise in sea levels that could submerge land, currently home to 470 to 760 million people. It could also mean unstoppable rise of sea levels over centuries to come. “A 4 degrees Celsius warming scenario could lock in enough sea level rise to submerge land inhabited by half or more of today’s population in Shanghai and Shantou, China; Haora (Howrah), Calcutta and Mumbai, India; Hanoi, Vietnam; and Khulna, Bangladesh,” the report said. The report, however, added that aggressive carbon cuts, resulting in 2°C warming, could bring down the number of people who will get affected to 130 million.

According to the report, China faces maximum risk with 145 million people under threat due to rising sea levels, if emissions are not reduced. Besides China, the report said 12 other nations, including India, Bangladesh, Indonesia and Vietnam, each have more than 10 million people at risk.

According to the report, China faces maximum risk with 145 million people under threat due to rising sea levels, if emissions are not reduced. Besides China, the report said 12 other nations, including India, Bangladesh, Indonesia and Vietnam, each have more than 10 million people at risk. Mumbai has 11 million people at risk after 4°C of warming; the number drops to 5.8 million in case of 2°C warming.