Forewarned is forearmed.

That seems to be the sentiment behind a new tool developed to identify the cities most at risk of flooding as the ice sheets melt.

The interactive tool, known as Gradient Fingerprint Mapping (GFM), was developed by scientists at NASA's renowned Jet Propulsion Laboratory in California.

Their invention predicts which areas of ice may contribute to sea level changes in individual cities.

This provides researchers with unprecedented insight into which ice sheets (and cities) they should be “most worried about”.

The tool works by taking into account the Earth’s rotation and gravitational effects to paint a broader picture of how certain melting points impact cities. Users of the tool can then pick from 293 cities to see how melting ice structures might affect different coastal regions.

According to scientists involved in its development, what makes GFM particularly unique is its ability to pinpoint the areas of ice that might impact particular cities.

As Dr Eric Larour from NASA explains: "We can compute the exact sensitivity – for a specific town – of a sea level to every ice mass in the world."

The predictions are not without their surprises, however. For instance, proximity is not the ultimate indicator of which glaciers should spark the most concern.

According to the researchers, New York City actually faces the biggest threat from Greenland’s northeast glaciers (those furthest away). By contrast, the northwestern region of Greenland’s ice sheet should be of most concern to Londoners.

The image shows the area of Greenland’s ice sheet that is of most concern to New York City. Red indicates the greatest sea level contribution.
Image: NASA/JPL-Caltech

With scientists projecting sea levels could rise two feet (0.6 metres) above 2005 levels by the end of the century – and a more recent study emphasizing the threat to coastal communities – the tool’s developers hope it will play a role in combating the effects of climate change.

As senior scientist Dr Erik Ivins explains, GFM enables coastal planners to make insightful decisions about how to confront rising sea levels.

Speaking to the BBC, Ivins said: “As cities and countries attempt to build plans to mitigate flooding, they have to be thinking about 100 years in the future and they want to assess risk in the same way that insurance companies do."