A glacier front meets the sea in Antarctica. The ice sheet holds enough water to raise global sea level by about 190 feet (58 meters). Photo: Qiyue Sun.

Yucheng Lin, City University of Hong Kong and Robert Kopp, Rutgers University

Sea-level rise is one of the most visible signs of climate change, one that is threatening low-lying coastal communities around the world. Today, about 1 billion people live in coastal areas; about 100 million live within 1 meter (3.3 feet) of sea level, highly exposed to coastal flooding.

Over the long term, when it comes to future sea-level rise, one place matters more than any other: Antarctica.

The frozen continent holds enough ice to raise global sea level by about 190 feet (58 meters). Yet scientists have disagreed on a fundamental question: Will Antarctica gain more ice than it loses this century or lose more ice than it gains?

In a new study published in the scientific journal Nature Geoscience, we looked at hundreds of thousands of potential futures and the impact of each on the ice sheet.

We found that Antarctica’s ice loss this century is locked in – even if the world limits global warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit), the 2015 international Paris climate agreement’s most ambitious goal.

Why the Antarctic ice sheet is so hard to predict

The Antarctic ice sheet’s future depends on a chain of events.

Greenhouse gas emissions from vehicles, coal- and natural gas-fueled power plants and other sources around the world determine how much the ocean and air around Antarctica warms. That warming shapes how ice shelves around the continent’s margins melt, and how quickly the glaciers behind........

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