West Antarctic Ice Melt Affects Sea Level Rise

New research indicates that accelerating ice loss in vulnerable West Antarctic ice shelves is almost inevitable in the coming century as surrounding waters warm. This development could suggest that previous predictions of one to three feet of sea level rise by 2100 were too conservative.

The study reveals that, irrespective of aggressive human efforts to reduce fossil fuel emissions and mitigate global warming, the waters around certain West Antarctic glaciers are expected to warm at a rate three times faster than historical norms. This accelerated warming is anticipated to result in widespread ice shelf melting, particularly in regions critical for ice-sheet stability.

Kaitlin Naughten, the lead author of the study and an ocean modeler with the British Antarctic Survey, expressed concern, stating, “It appears we may have lost control of the West Antarctic ice shelf melting over the 21st century. That very likely means some amount of sea level rise that we cannot avoid.”

This research further emphasizes the likelihood that some polar ice systems have already crossed a tipping point, entering a phase of escalating decline. Arctic sea ice has been diminishing for several decades, with data indicating irreversible thinning in the North Pole region since 2007. While Antarctic sea ice has been more stable, it is now showing signs of significant declines. The South Pole recently experienced record-low sea ice cover, and last month, it reached the smallest observed winter maximum.

As the Southern Ocean warms and thins the floating sea ice, it poses an increasing threat to the ice shelves. This study aligns with the conclusions of numerous previous research efforts, suggesting that the West Antarctic ice sheet is on a trajectory toward eventual collapse.

The study focused on the Amundsen Sea, an area of the Southern Ocean surrounding some of Antarctica’s largest glaciers, which are buttressed by the thinning and retreating ice shelves. Notably, Thwaites Glacier, often referred to as the “doomsday” glacier, is among these, and its retreat could potentially compromise the heart of West Antarctica.

Projections in the study indicate that sea temperatures in the Amundsen Sea will rise significantly in various future warming scenarios, regardless of whether global warming is limited to the ambitious target of 1.5 degrees Celsius agreed upon in the Paris Agreement or more moderate emissions pathways.

While the research suggests that the melting of the ice shelves is nearly unavoidable, it’s important to note that their melting doesn’t directly contribute to sea level rise. However, their vulnerability raises concerns about the potential flow of massive grounded ice cover into the Southern Ocean, which could eventually lead to sea level rise.

The latest report from the U.N. Intergovernmental Panel on Climate Change predicts a modest contribution to sea level rise from Antarctica by 2100. The report’s central predictions indicate only about a third of a foot of sea level rise by the end of the century due to ice losses from Antarctica. However, the new research suggests that this outlook may worsen, although the extent of the impact remains uncertain and may become more dramatic after 2100.

The study findings are not yet incorporated into the IPCC’s sea level rise projections, as estimating sea level rise from the expected warming in the Amundsen Sea is a complex task involving various factors such as melting, snowfall, and glacier flow.

While Thwaites Glacier is currently experiencing accelerated ice loss, it has contributed only a small amount to sea level rise since the late 1970s. Scientists are concerned that the situation may worsen in the coming decades, although it will take some time to reach a critical point.

In summary, this research underscores the urgency of addressing greenhouse gas emissions and preparing for the inevitable effects of climate change, including sea level rise. While the ice shelves near the Amundsen Sea may contribute to sea level rise, they represent only a fraction of Antarctica’s ice, and there is still an opportunity to mitigate the impact on other regions and ecosystems.