A team of scientists has conducted simulations on the UK's national supercomputer to investigate the melting of the West Antarctic ice sheet, to explore how much unavoidable melting needs to be adapted to, and how much melting the international community can still control by reducing greenhouse gas emissions, taking into account climate variability such as El Niño.

The research team from the British Antarctic Survey did not find much difference between medium-term emissions scenarios and the more ambitious targets of the 2015 Paris Agreement.

As the authority's press release notes, even under the best-case scenario of a global temperature rise of only 1.5 degrees Celsius, the melting of ice will increase 3 times faster than in the 20th century.

Looks like we've lost control.

The West Antarctic ice sheet collectively contains enough ice to raise the global average sea level by up to 5 meters. Dangerous is that we are losing this ice sheet, and previous models have found that this loss could be caused by warming of the Southern Ocean, especially the Amundsen Sea region.

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

Dr Caitlyn Nutton, lead author of the study published in the journal Nature Climate Change, said: "We seem to have lost control of the melting of the West Antarctic ice sheet, and if we wanted to preserve it in its historical state, we would have taken action on climate change decades ago."

The silver lining is that by acknowledging this situation in advance, the world will have more time to adapt to the upcoming sea level rise, she adds. "If you need to abandon a coastal area or redesign it entirely, 50 years ahead of you will make the difference," he said.

What we are doing now will help slow the rate of long-term sea level rise (Shutterstock)

Simulation of scenarios

The team simulated 4 future scenarios for the 21st century, as well as one historical scenario for the 20th century. Future scenarios were either to stabilize global temperature rise at the targets set by the Paris Agreement, which are between 1.5°C and <>°C, or to follow standard scenarios for medium and high carbon emissions.

All scenarios have led to significant and widespread future warming of the Amundsen Sea and further melting of its ice shelves. The three scenarios with a lower temperature range followed almost identical trajectories during the 21st century.

Even under the best-case scenario, the warming of the Amundsen Sea accelerated by about 3-fold, followed by the melting of floating ice shelfs that stabilize inland glaciers, although they began to flatten by the end of the century.

The worst-case scenario was the melting of the ice shelf, but only after 2045. The authors, however, note that this high fossil fuel scenario, where emissions are increasing rapidly, is unlikely to happen.

"We must not stop working to reduce our dependence on fossil fuels. What we are doing now will help slow the rate of sea level rise in the long run. "The slower the changes in sea level, the easier it is for governments and society to adapt to it, even if it can't be stopped."