Major Ice Sheets May Already Be Past The Point Of No Return: Study

The Greenland and Antarctic ice sheets are melting fast, and the process may be impossible to stop, a new study has warned. This could lead to several feet of sea level rise and force millions to leave coastal areas. Even if global warming is capped at the 1.5-degree Celsius threshold agreed upon by world leaders, the melting may continue unabated, scientists added.

Published on Tuesday in Nature, the study brings together findings from satellite data, climate models, and paleoclimate records, including ice cores, deep-sea sediments, and even octopus DNA, to determine the "safe limit" of warming for the survival of Earth's largest ice sheets.

The results say that even current warming levels of around 1.2 degree C could set off unstoppable ice sheet retreat. And with the world on track for up to 2.9 degree C of warming by 2100 if emissions continue, the situation could become much worse.

Together, the Greenland and Antarctic ice sheets contain enough frozen water to raise global sea levels by approximately 213 feet. While such an outcome is considered extreme, the study says there is a risk of major, multi-foot sea level rise over time. Ice loss from these regions has quadrupled since the 1990s, with around 370 billion tons melting each year, making them the biggest contributors to rising seas. The pace of sea level rise has doubled in the past 30 years.

"You don't slow sea level rise to 1.5, in fact, you see quite a rapid acceleration," Chris Stokes, glaciologist and study co-author from Durham University, told CNN.

Today, about 230 million people live less than one metre (around 3.2 feet) above sea level. The study warns that even small amounts of ice melting could reshape coastlines, force hundreds of millions to move, and cause damage beyond what many places can handle.

By 2100, sea levels could rise by 0.4 inches every year, adding up to around 40 inches over the century.

Scientists say it is hard to know exactly when ice sheets will hit a tipping point, but the danger is closer than they thought. Earlier research suggested the Greenland ice sheet would only start collapsing at around 3 degree C of warming. Now, it may happen at just 1.5 degree C.

To stop this, global warming would need to be kept closer to 1 degree C, which means cutting fossil fuel use sharply. With countries like the US still using oil, coal, and gas, experts say this goal is unlikely.

"There's very little that we are observing that gives us hope here," said Mr Stokes. "The absolute best-case scenario is that sea level rise is slow and steady."

Still, the researchers say that staying as close as possible to the 1.5 degree C target remains vital. "Limiting warming to 1.5 will be a major achievement. It should absolutely be our target, but in no sense will it slow or stop sea level rise and melting ice sheets," Mr Stokes added.