“We have lost control” – the inevitable collapse of the West Antarctic ice sheet

The rate of melting of the West Antarctica ice sheet is expected to rise significantly this century, regardless of fossil fuel cuts. While the future looks full of challenges, reducing dependence on fossil fuels remains vital for adaptation and mitigation.

The West Antarctic Ice Sheet will continue to melt at an increased rate over the rest of the century, no matter how much we reduce the use of fossil fuels, according to British Antarctic Survey (BAS) research published this week in the journal. The nature of climate change. A significant acceleration in ice melt is now unlikely to be avoided, which implies that Antarctica’s contribution to sea level rise could increase rapidly over the coming decades.

Credit: Bass

Scientists ran simulations on the UK’s national supercomputer to investigate ocean-driven melting of the West Antarctic Ice Sheet: how much melting is unavoidable and must be adapted to, and how much melting can still be controlled by the international community by limiting emissions Greenhouse gases.

Taking into account climate fluctuations such as El Niño, they found little difference between medium-term emissions scenarios and the more ambitious targets in the 2015 Paris Agreement. Even under the best-case scenario of a 1.5°C global temperature rise, ice melt would triple Faster than it was during the 1920s.^y a century.

The broader context and its implications

The West Antarctica Ice Sheet is losing ice and is the largest contributor to sea level rise in Antarctica. Previous models found that this loss could be caused by warming of the Southern Ocean, especially the Amundsen Sea region. Combined, the West Antarctica ice sheet contains enough ice to raise global average sea level by up to five metres.

The West Antarctica ice sheet will continue to melt at an increasing rate over the rest of the century, no matter how much we reduce the use of fossil fuels. Credit: Bass

2. 

Millions of people around the world live near the coast, and these communities will be greatly affected by sea level rise. A better understanding of future changes would allow policymakers to plan for the future and adapt more easily.

Expert insights and scenario analysis

“We appear to have lost control of the melting of the West Antarctic ice sheet,” says lead author Dr Caitlin Naughton, a researcher at the British Antarctic Survey. If we wanted to preserve it in its historic condition, we would have needed to take action on climate change decades earlier. The bright side is that by being aware of this situation in advance, the world will have more time to adapt to the upcoming rise in sea level. If you need to abandon or significantly redesign a coastal area, having a 50-year lead time will make a big difference.

The team simulated four future scenarios for the 21^street century, in addition to one historical scenario for the twentieth century^y a century. Future scenarios either stabilize global temperature rise at the targets set by the Paris Agreement, which are 1.5 degrees Celsius and 2 degrees Celsius, or follow standard scenarios for medium and high carbon emissions.

The team simulated four future scenarios for the 21st century, as well as one historical scenario for the 20th century. Credit: Bass

All scenarios lead to a significant and widespread warming of the Amundsen Sea in the future and increased melting of its ice shelves. The three lower-scale scenarios followed almost identical trajectories over the 21 days^street a century. Even under the best-case scenario, the warming of the Amundsen Sea accelerated by about a factor of three, followed by the melting of floating ice shelves that stabilized the inland glaciers, although they began to flatten by the end of the century.

The worst-case scenario had the ice shelf melting more than the other scenarios, but only after 2045. The authors note that this high-fossil fuel scenario, where emissions increase rapidly, is considered unlikely to happen.

Conclusion and call to action

This study presents realistic future projections for ice shelf melting in the Amundsen Sea, but does not undermine the importance of mitigation in reducing the effects of climate change.

“We should not stop working to reduce our dependence on fossil fuels,” warns Naughton. “What we do now will help slow the rate of sea level rise in the long term. The slower the changes in sea level, the easier it will be for Governments and society adapt to it, even if it cannot be stopped.

Reference: “Unavoidable Future Increase in Melting of the West Antarctic Ice Shelf During the 21st Century” by Caitlin A. Naughton, and Paul R. Holland, Jean de Redt, October 23, 2023, The nature of climate change.
doi: 10.1038/s41558-023-01818-x