New Tipping Point Discovered in Antarctic Ice Melt, Threatening Global Sea Levels

Scientists have identified a new tipping point that could accelerate the “runaway melting” of Antarctic ice sheets, driven by warm ocean water seeping between the ice and the land, according to a study published on Tuesday in Nature Geoscience. This phenomenon, previously studied, has not yet been included in models used by the United Nation’s Intergovernmental Panel on Climate Change (IPCC) to forecast the impacts of global warming on Antarctica.

The study asserts that current IPCC models have consistently underestimated the extent of ice loss observed so far. As human-caused global warming increases ocean temperatures, Antarctic ice sheets are melting at a faster rate, posing a significant threat to global sea levels and coastal communities worldwide.

“Increases in ocean temperature can lead to a tipping point being passed, beyond which ocean water intrudes in an unbounded manner beneath the ice sheet, via a process of runaway melting,” the study explains. Antarctic ice sheets rest atop bedrock and extend beyond the coast to float on the ocean. Warm seawater infiltrates the “grounding zone” – where land and ice converge – and moves further inland beneath the floating ice, accelerating the melting process.

Lead author Alexander Bradley, a researcher with the British Antarctic Survey, highlights that even minor increases in ocean temperature can drastically enhance this process. “Every 10th of a degree (of warming) makes these kind of processes closer, these tipping points closer,” Bradley noted. The primary concern is that accelerated melting could outpace the formation of new ice, leading to a net increase in sea levels.

Certain regions of Antarctica are more susceptible to this process due to the topography of the land, which features valleys and cavities where seawater can pool beneath the ice. The Pine Island glacier, currently the largest contributor to sea-level rise from Antarctica, is at significant risk due to the land’s slope, allowing more seawater to penetrate and melt the ice.

Bradley emphasizes the need to update scientific models to include this melting factor to better predict future sea-level rise and prepare accordingly. “And it really just stresses the need for urgent climate action in order to prevent these tipping points from being passed,” he added.

This discovery underscores the critical importance of immediate and effective climate action to mitigate the potential catastrophic impacts of accelerated Antarctic ice melt on global sea levels.