Global warming: NASA tool predicts which city will flood first; Mangalore, Mumbai at risk

Karnataka’s Mangalore may be at higher risk of drowning due to sea level rise triggered by glacial melting than cities such as Mumbai and New York, data released by a NASA study shows.

It is well known that the melting of glaciers will lead to sea level rise, what is not as well understood is how the melting in different regions of ice sheets will impact local sea levels at coastal cities.

Now a new tool developed by NASA scientists called Gradient fingerprint mapping (GFM) allows planners and the public to forecast just that.

The study finds that sea level rise caused by the melting of glaciers is not uniform across the globe since local factors play a role. Mangalore will see a higher local sea level (1.598 mm) than Mumbai (1.526 mm) in case of the same level of ice loss in glaciers in Antarctica and Greenland.

“People can be desperate to understand how these huge, complicated global processes impact on them,” Dr Surendra Adhikar, a member of the team, told BBC. “With this tool, they can see the impact on their own city.”

The researchers at NASA’s Jet Propulsion Laboratory in California applied the tool to 293 major port cities including Manguluru or Mangalore in Karnataka.

Almost 75% of the world’s freshwater is stored in glaciers, mostly in Greenland and Antarctica. Melting of icesheets on both is a major contributor to sea level rise. The tool measures how sensitive local sea level rise is to the change in thickness of the ice sheet, that captures how much ice the sheet has lost.

The sensitivity is measured in terms of Gradient −dS/dH and classified into four bands (-4 to -2, -2 to 0, 0 to 2, 2 to 4).

For Mangalore the sensitivity is high to changes in ice thickness in almost all regions of the Greenland and the Antarctic ice sheet. However, it is more sensitive to changes in the western part of the Antarctic ice sheet and the southern part of the Greenland ice sheet.

For New York, the melting of northern and eastern portions of Greenland is more dangerous, and for London the local sea level rise would be impacted more by changes in the north-western part of the Greenland ice sheet.

In South Asia all cities studied: Chittagong, Colombo and Karachi showed high sensitivity to melting glaciers in Greenland and Antarctica.

The research was published in the journal Science Advances.

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