Despite efforts to reduce carbon emissions, new research reveals that the melting of West Antarctic ice shelves will accelerate rapidly throughout the century. This phenomenon, driven by a warming Southern Ocean, is expected to result in rising sea levels, posing significant challenges for coastal communities worldwide.
The Antarctic Ice Sheet and Ice Shelves
The Antarctic ice sheet, the largest body of land-based ice on Earth, is a complex system of interconnected glaciers formed by year-round snowfall. Coastal ice shelves, floating extensions of this ice sheet, play a crucial role in stabilizing the glaciers behind them. These ice shelves are vulnerable to melting from below by the ocean, and as they thin, the rate at which glaciers discharge freshwater into the ocean increases, contributing to rising sea levels.
Ongoing Process in West Antarctica
This process has been underway for decades in West Antarctica, particularly in the Amundsen Sea. Here, ice shelves are thinning, glaciers are accelerating their flow into the ocean, and the ice sheet is diminishing. Although limited ocean temperature measurements are available for this region, climate change modeling suggests that it has experienced warming.
Research Methodology
A detailed analysis of ice-shelf melting in the Amundsen Sea, the most vulnerable sector of the ice sheet, was conducted. A regional ocean model was employed to predict how ice-shelf melting would evolve between the present and 2100. Researchers considered various scenarios related to fossil fuel burning, ranging from an optimistic 1.5°C warming limit (aligned with the Paris Agreement) to uncontrolled coal, oil, and gas usage. Natural climate variations, such as El Niño events, were also taken into account.
Unavoidable Melting
The results are concerning. In all scenarios, there is a significant acceleration in ocean warming and ice-shelf melting throughout this century. Even in the best-case scenario of halting warming at 1.5°C, which is considered ambitious, there is a threefold increase in the historical rate of melting. Surprisingly, little difference exists between the scenarios up to 2045, including the mid-range scenario approximating existing pledges to reduce fossil fuel consumption.
Strengthening Ocean Currents
The increasing warming and melting are primarily due to strengthening ocean currents, which transport warmer waters from the deep ocean to the shallower ice shelves along the coast. This process is likely responsible for the thinning of ice shelves observed by satellites.
Sea Level Rise Implications
While ice-shelf melting contributes significantly to sea-level rise, it is only part of the equation. To accurately predict future sea-level rise, the flow of Antarctic glaciers and the rate of snow accumulation on the ice sheet must also be considered. Still, there is a strong belief that increased ice-shelf melting will lead to accelerated sea-level rise.
Future Preparedness
Although the melting of West Antarctica may be inevitable until 2100, there is hope in the longer term. The future extends beyond 2100, and efforts to reduce sea-level rise can be focused on that horizon. By adapting to these changes, protecting coastal communities where possible, and planning for the future, we can address the long-term challenges posed by sea-level rise.
