Antarctic Ice Shelf Melting to Accelerate, Raising Concerns for Rising Sea Levels

A new study warns that increased melting of West Antarctica’s ice shelves is “unavoidable” in the coming decades, with potentially significant implications for future sea-level rise. Ice shelves, which extend into the ocean from the main ice sheet, play a crucial role in holding back glaciers. However, as these ice shelves melt, they can trigger the acceleration of ice behind them, releasing more into the oceans.

The findings of this study suggest that future sea-level rise may be more substantial than previously estimated, raising concerns about the impact on coastal communities. The lead author of the report, Dr. Kaitlin Naughten of the British Antarctic Survey (BAS), emphasized that these findings increase the likelihood that current estimates of sea-level rise will be exceeded.

In 2021, the Intergovernmental Panel on Climate Change (IPCC) released projections for global average sea-level rise by 2100, estimating a range between 0.28 meters and 1.01 meters. Melting glaciers and ice sheets were identified as a key factor contributing to this rise. Even a one-meter increase in sea levels can pose a significant threat to coastal regions, affecting millions of people worldwide.

However, the IPCC also acknowledged uncertainties related to “ice-sheet-related processes,” not directly included in their estimates. This latest study, published in the journal Nature Climate Change, is the first to simulate how ocean warming, driven by greenhouse gas emissions, will impact Antarctic ice shelves.

The study indicates that the Amundsen Sea, off the coast of West Antarctica, will warm at a rate approximately three times faster than historical averages. This rapid warming will lead to increased melting of ice shelves, even if significant efforts are made to reduce emissions. Dr. Naughten underlines the importance of taking immediate action to slow the rate of sea-level rise in the long term.

While the study’s conclusions are significant, the authors stress the need for further research to enhance confidence in their findings. The melting of ice shelves in West Antarctica is of particular concern due to its potential impact on the broader region.

West Antarctica contains a substantial amount of ice that, if fully melted, could raise global sea levels by approximately 58 meters. Most of this ice is located in East Antarctica, which has been relatively stable. In contrast, West Antarctica has been losing mass in recent decades, making it less stable.

Ice shelves are critical in holding back the ice mass on land. As these shelves melt due to warm ocean waters, the glaciers behind them may accelerate. This acceleration can result in more ice entering the ocean through melting or breaking off as icebergs. Moreover, a significant portion of West Antarctica is located below sea level, allowing glaciers to retreat into deeper waters, further accelerating ice loss.

One particularly vulnerable area is the Thwaites Glacier, often referred to as the “doomsday glacier” due to its potential to raise global sea levels significantly if it collapses entirely. The grounding line of the Thwaites Glacier is already retreating rapidly in some areas, highlighting its susceptibility to warming.

The processes initiated by accelerated ice shelf melting could lead to the collapse of the West Antarctic Ice Sheet. However, additional factors, such as snowfall, surface ice melting, and glacier flow rates, also influence the ice sheet’s response to warming and the speed of sea-level rise.

It is widely acknowledged that sea levels will continue to rise in the coming decades and centuries. The slow adjustment of ice sheets to recent rapid warming means further temperature increases are expected. This study adds weight to the idea that sea-level rise may happen more rapidly due to increased ice shelf melt, necessitating adaptation measures for societies worldwide.

Dr. Naughten emphasizes that it is essential to address the root causes of ice shelf melting by reducing greenhouse gas emissions. This action can offer societies the necessary time to prepare for and adapt to rising sea levels.

Alberto Naveira Garabato, a professor in physical oceanography at the University of Southampton, adds that this research should serve as a “wake-up call.” It underscores the urgency of reducing greenhouse gas emissions to protect the Antarctic Ice Sheet and mitigate the potential for sea-level rise.