The sea level along the Indian coast has risen by 8.5cm over the past 50 years, Union minister of state for environment Babul Supriyo told the Rajya Sabha on Tuesday, outlining figures in line with the global average sea-level rise over the past century.

“On an average, the sea level along the Indian coast is considered to be rising at about 1.7mm per year,” Supriyo said in a written response to a question on whether several cities will be submerged under the effects of global warming.

The minister said that while rising sea levels could exacerbate coastal inundation along low-lying areas during storm surges or flooding, the actual area that could be inundated due to rising sea levels needs to be evaluated, based on their elevation above the mean sea level.

“Since no long-term data on land subsidence or emergence are available for these locations, the rate of increase of sea level due to climate change cannot be attributed with certainty,” he said.

“For example, a higher high rate of sea level increase at Diamond Harbour is also due to the larger land subsidence happening there. The same may apply to Kandla, Haldia and Port Blair as well.”

An independent scientific study released last month had tripled the global estimates of population threatened by rising sea levels, predicting that sea-level rise would push average annual coastal floods higher than land currently inhabited by 300 million people worldwide.

The new estimates based on improved elevation data indicate that even with moderate reductions in Earth-warming greenhouse gas emissions, around 36 million people in India will be at risk of annual coastal flooding by 2050, compared to current estimates of 5 million.

The study by scientists Scott Kulp and Benjamin Strauss with Climate Central, an independent research organisation, and published in the journal Nature Communications, had projected Bengal and Odisha as particularly vulnerable to the rising sea levels.

In an accompanying media release, the researchers had said that by mid-century, Calcutta would be among other cities worldwide where significant areas would be at risk of annual coastal flooding.