A new study published in the journal Nature Geoscience has revealed a concerning tipping point in the melting of Antarctic ice sheets. Scientists have discovered that as ocean temperatures rise due to human-caused global warming, warm ocean water is intruding between the ice and the land it sits on, leading to a process of “runaway melting.”

While this type of melting has been previously studied, the models used by the United Nation’s Intergovernmental Panel on Climate Change (IPCC) to project the impact of global warming on the Antarctic have not yet factored in this phenomenon. The study also found that these models have systematically underestimated the ice loss seen thus far.

Alexander Bradley, the lead author of the study and a researcher with the British Antarctic Survey, explained that even a fraction of a degree increase in water temperature can cause the intrusion to accelerate from short distances of 100 meters to tens of kilometers, melting ice along the way by heating it from below. “Every 10th of a degree of warming makes these kind of processes closer, these tipping points closer,” said Bradley. The risk to sea-level rise becomes apparent when the accelerated melting outpaces the formation of new ice on the continent.

Antarctic ice instability threatens coastlines

Some areas of Antarctica are more vulnerable to this process than others due to the shape of the land mass, which has valleys and cavities where seawater can pool beneath the ice. The Pine Island glacier, currently Antarctica’s largest contributor to sea-level rise, is at high risk of melting due to the slope of the land that allows in more seawater, according to the study.

Bradley emphasized the need for scientific models to be updated to take into account this phenomenon to better predict the risk of sea-level rise in the future and prepare for it. He also stressed the urgent need for climate action to prevent these tipping points from being passed. The findings of this study have significant implications for coastal communities around the world, as they highlight the urgency to address climate change more aggressively.

As research continues to uncover the complex processes driving ice-sheet retreat, it becomes increasingly clear that improved ice-sheet models incorporating feedbacks between melting and ice geometry are crucial for accurately predicting future sea-level rise.