Thaw in Antarctica could set off chain reactions and cause monsoon rains on the ice sheet, study finds

(CNN) – In an increasingly warmer climate, domino effects or chain reactions could cause alterations in weather patterns around the world as a result of the melting of the Antarctic ice sheet, according to a new study.

The study, published in the Nature Geoscience journal, has found that as the Earth continues to warm, the land under the Antarctic ice sheet will be more exposed. As a result of that process, wind patterns will change and precipitation will increase over Antarctica, which could trigger processes that accelerate ice loss.

“We found that the retreat of the ice sheet, exposing previously ice-covered areas, causes a large increase in precipitation, which through a feedback mechanism dramatically warms the ocean,” Catherine Bradshaw, lead scientist at CNN, told CNN. the UK Met Office and Professor at the University of Exeter.

“This feedback mechanism could trigger additional processes that accelerate ice loss.”

The joint study is based on the combination of climate models and data comparisons from the Middle Miocene epoch (13-17 million years ago).

Why are we interested in something that happened more than 13 million years ago? Because carbon dioxide levels and global temperatures during the Middle Miocene were similar to what the Earth is predicted to reach at the end of this century.

When it rains, it thunders

“With the great Antarctic ice sheet like we have today, the prevailing winds are known as katabatic winds, and they go from land to sea,” Bradshaw told CNN. «They originate in the ice sheet, in a very high place, very cold and very dry; in fact, Antarctica only receives a few inches of snow a year and is so dry that it is classified as a desert.

Bradshaw warns that if Antarctica continues to warm, those winds could reverse and blow from the cooler sea to warmer and drier land. This would generate the same results that we see in daily sea breezes and seasonal monsoon winds that occur around the world.

A monsoon is simply a seasonal reversal of wind direction that results in changes in precipitation for a specific region of the planet. For Antarctica, this means increased rainfall.

Bradshaw warns that if Antarctica continues to warm, those winds could reverse and blow from the cooler sea onto warmer and drier land. This would generate the same results that we see in daily sea breezes and seasonal monsoon winds that occur around the world.

A monsoon is simply a seasonal reversal of wind direction that results in changes in precipitation for a specific region of the planet. For Antarctica, this means increased rainfall.

‘The surface of the Antarctic ice sheet is very bright, reflecting 50-80% of the sunlight that falls on it. When the ice sheet recedes, exposing the darker Earth’s surface below, this soil is much less reflective and therefore absorbs more sunlight, thus heating up, ”Bradshaw told CNN.

Bradshaw explained that the ice-free soil on the coast heats up more than the surrounding sea surface, which in turn causes the change in wind direction. Like the ocean breezes Florida experiences, these winds can bring in moisture from the surrounding ocean that can dramatically increase rainfall.

“What happens to an ice sheet when precipitation increases depends on where the rain falls and whether it is cold enough to fall as snow rather than rain,” explains Bradshaw.

‘If temperatures are warm enough for moisture to rain down on the ice-free zone, this could trigger processes that can accelerate ice loss. Conversely, if temperatures are cold enough for moisture to fall as snow onto the ice sheet, this can cause ice to grow. ‘

As the Earth continues to warm, scientists could learn from the world’s monsoon regions about how to avoid a collapse of the Antarctic ice sheet. While this may sound a bit far-fetched, this new research shows that this may have happened in the past, when the Antarctic ice sheet was even more unstable.

“Essentially, if more land is exposed in Antarctica, it becomes more difficult for a large ice sheet to reform, and without the influence of (favorable) orbital positions in the Middle Miocene, perhaps the ice sheet would have collapsed in that moment, “he said Bradshaw in a press release.

Although the study suggests that the Antarctic ice sheet was able to move back and forth across the continent during the Middle Miocene, Dr. Bradshaw stresses that conditions today are not identical to those millions of years ago.

“It is important to emphasize that there were many important processes that were not included in our study and that, based on our findings, require additional research to establish exactly what the implications are for the future,” Bradshaw told CNN. “That is the work that I intend to do next, but have not started yet.”

Walking on ice

The increase in rainfall on the Antarctic continent not only has local but also global repercussions, since these new rains would cause more fresh water to end up in the surrounding oceans, in turn causing the sea level to rise.

“The rain ends up going back into the sea, and because it is fresh water and not salt water, it is less dense than the sea water that it goes to,” Bradshaw explained to CNN. “This means that it can form a layer on the surface instead of sinking and circular.”

This is important because essentially a separation point has now been created between the deep ocean and the ocean surface, causing the deep waters warm.

“Since much of the West Antarctic ice sheet, in particular, is below the sea surface, warmer waters can interact with the ice sheet from below,” said Bradshaw.

‘If the surface of the ice sheet is melting, it can form meltwater lakes to which rain can add. Meltwater lakes tend to be blue rather than white, making them darker than the ice below and thus absorbing more sunlight, thus heating them up. ‘

This can create a ripple effect where these darker, warmer waters could cause the ice sheet to melt from the inside out. So the worst case scenario now is that the ice sheet not only melts from within, but also shrinks on the coast.

“Near the coast, the ice flows faster in ice currents, glaciers and ice shelves and is lost to the ocean as meltwater or icebergs,” Bradshaw told CNN. “Without new snowfall to replace the ice that is constantly being lost, the ice sheet will lose mass.”

Although this study focused primarily on Antarctica, there have also been notable changes in ocean temperatures and salinity not only in the southern hemisphere, but also in the northern hemisphere, due to the melting of the ice. Greenland ice sheet.

This dramatic melting of the world’s ice sheets could lead to dramatic changes in weather patterns. The degree of stability or instability of the Antarctic ice sheet has not yet been accurately determined. However, one thing is certain and that is that the ice is in constant motion.

–CNN meteorologist Haley Brink contributed to this report.