Antarctica's ice loss is locked in, and extra snowfall won't save it—low‑lying coastal areas elsewhere to suffer

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: 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. 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 warm. That warming shapes how ice shelves around the continent's margins melt and how quickly the glaciers behind them slide over the bedrock. When those ice shelves thin or collapse, studies show the glacier flow speeds up.

Each step relies on assumptions that scientists have yet to agree on, such as how ice shelves collapse. Different assumptions give different answers, and because each step feeds the next, the differences grow—what scientists call cascading uncertainty. As a result, research teams around the world can't agree on whether Antarctica will gain or lose ice this century.

Snow is part of the puzzle. Warmer air holds more moisture, so as temperatures rise, more snow will likely fall on Antarctica. In some projections, that extra snow outweighs the ice lost to the warming ocean, and the ice sheet actually grows.