Why is Antarctic ice more susceptible to warming?

Examination of the Antarctic ice sheets from the early Miocene, aged 18-16 million years, which experienced both hot and cold periods, suggests that they may be more susceptible to warming.

Understand how to coat Es Antartika West to a warmer climate millions of years ago could improve predictions about its future, and a new study published in Nature found that during warmer periods, sea levels rose by up to 60 meters, which is equivalent to the melting of existing ice. Antarctica.

However, it is not known with certainty that the contribution of the Greater East Antarctic Ice Sheet (EAIS) and West Antarctic Ice Sheet (WAIS) to past sea level rise is unclear. Imperial College scientists working under the International Ocean Discovery Program are now showing that the WAIS range was larger than previously thought during the colder Miocene period.

This means that it contributed more to sea level rise millions of years ago than previously thought. This information will help researchers predict the future of WAIS more accurately as the world warms.

WAIS was previously thought to be relatively young before the end of the Miocene, about 10 million years ago, and sea level rise was the result of the largest melting of the East Antarctic Ice Sheet (EAIS), quite possibly during warmer periods in the past. 23 million years.

However, although the geological record shows significant sea level rise, ice sheet models suggest that parts of the EAIS persisted even during the hottest period of the Miocene, about 23-5 million years ago.

Lead author Jim Marshall of the Department of Earth Science and Engineering at Imperial is completing his Ph.D. with the Association for Doctoral Training in Science and Solutions for a Changing Planet.

According to him, his observations of the past help scientists to inform scientists about the state of the Earth.

Our observations from the past help make predictions about how the West Antarctic ice sheet, which is particularly vulnerable to rapid ice mass loss today, will respond under a variety of future warming scenarios. “

sediment drilling

The research team drills into sediments in the Ross Sea in Antartika, to find layers that correspond to the coldest and hottest periods. They found evidence of material deposited by WAIS deep into the ocean, suggesting that it grew during cold periods.

This is possible because in the past much of the land beneath the WAIS was above sea level, allowing more ice to settle on this part of the continent than it is today. Despite these geographic changes, this study shows how WAIS could raise sea levels by a significant amount in the future as our planet warms.

Currently, WAIS is highly vulnerable to ocean and atmospheric warming. This new study supports this idea by showing that it expanded and shrunk significantly during the Miocene.

Man-made climate warming is currently happening at a very fast rate. Now that the geological information fits the model, scientists can be more confident that the model is capturing WAIS responses in the past, helping predict how WAIS will respond. Antartika For changes in the short term and over several hundred or thousands of years.

The results also show that the effects of climate change on the Antarctic ice sheet will persist if significant steps are not taken now to reduce greenhouse gas emissions.

Tina van de Vlerdt, a professor in the Department of Earth Science and Engineering at Imperial, says that “Although Antarctica is losing mass at an accelerating rate today, the projected sea level rise by the end of this century is nowhere near the rate we know existed in the geological past when temperatures were one, two or three degrees higher. Then, the past is an important window to tell us what to do with the planet with a certain amount of warming.”

The good news is that large ice sheets are relatively slow to respond to environmental changes, so we can still avoid significant ice loss in many areas. The bad news is that the bottom of the ice sheet has a tipping point, “and we still don’t understand where that point of no return is.”

For this reason, he recalls, “keeping future warming below 2 degrees, ideally 1.5 degrees, is the goal of reducing emissions by 50% by 2030.”

Research also shows that the massive WAIS is highly eroded, meaning more land is falling below sea level, permanently increasing the sensitivity of the West Antarctic ice sheet to changing ocean conditions.

The team says future work is needed to study the lower and vulnerable parts of each of the smaller ice sheets in more detail. Antartika West as the largest in East Antarctica.

–