The accelerated melting of West Antarctica is “inevitable”

  • Scientists have run simulations on the UK’s national supercomputer to investigate the melting of the West Antarctic ice sheet

The West Antarctic ice sheet will continue to increase its rate of melting in the remainder of the century, no matter how much the use of fossil fuels is reduced.

Research from the British Antarctic Survey (BAS) published in the journal Nature Climate Change warns that a substantial acceleration of melting may now not be avoided, implying that Antarctica’s contribution to sea level rise could increase. rapidly in the coming decades.

Scientists have run simulations on the UK’s national supercomputer to investigate ocean-driven melting of the West Antarctic ice sheet to find out to what extent it is inevitable and needs to be adapted to, and how much melting they still have control over. the international community by reducing greenhouse gas emissions.

Taking into account climate variability such as El Niño, they found no significant differences between mid-range emissions scenarios and the most ambitious goals of the 2015 Paris Agreement. Even in the best-case scenario, with a global temperature rise of 1.5 °C, melting will increase three times faster than in the 20th century.

The West Antarctic Ice Sheet is losing ice and is Antarctica’s largest contributor to sea level rise. According to previous models, this loss could be due to warming of the Southern Ocean, especially in the Amundsen Sea region. Together, the West Antarctic Ice Sheet contains enough ice to raise mean sea level by up to five metres.

Around the world, millions of people live near the coast and these communities will be greatly affected by rising sea levels. A better understanding of future changes will allow policymakers to plan ahead and adapt more easily.

Kaitlin Naughten, lead author of the study and researcher at the British Antarctic Survey, points out in a statement that “it seems that we have lost control of the melting of the West Antarctic ice sheet. If we wanted to preserve it in its historical state we would have had to act on climate change decades ago. The positive side is that by recognizing this situation in advance, the world will have more time to adapt to the coming sea level rise, she says. If a coastal region has to be abandoned or substantially remodeled, having 50 years in advance is going to make the difference.

The team simulated four future scenarios from the 21st century, plus one historical scenario from the 20th century. Future scenarios stabilized global temperature rise at the targets set by the Paris Agreement, 1.5°C and 2°C, or followed standard medium and high carbon emission scenarios.

All scenarios caused significant and widespread warming of the Amundsen Sea and further melting of its ice sheets. The three lower-ranking scenarios followed almost identical trajectories throughout the 21st century. Even in the best-case scenario, warming of the Amundsen Sea accelerated by a factor of three, and melting of the floating ice shelves that stabilize inland glaciers followed, although it began to flatten by the end of the century.

In the worst case, ice shelves melted more than others, but only after 2045. The authors warn that this high fossil fuel consumption scenario, in which emissions increase, is considered unlikely to occur. quickly.

This study presents sobering forecasts for the melting of the Amundsen Sea Ice Shelf, but does not undermine the importance of mitigation to limit the effects of climate change.

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