Up to a quarter of West Antarctic ice is unstable because of human-caused climate change – and the rate of ice melt is accelerating, with a study finding the white continent is melting at six times the speed it was in 1979.

But just as human activity is responsible for this ice loss, it could help bring it back. Researchers at the Potsdam Institute for Climate Impact Research (PIK) have published a study in Science Advances examining the possibility of physically generating supplementary snowfall from ocean water and distributing the icy slush via snow cannon. 

If it were to go ahead, it would involve an engineering feat of unprecedented proportions (in exceptionally harsh conditions), but it could provide a solution to long-term sea-level rise – a risk that threatens to see cities like Miami and Bangkok underwater by the turn of the century. 

However, saving these cities comes at a price, explains co-author Anders Levermann, a physicist at PIK and Columbia University.

"The fundamental trade-off is whether we as humanity want to sacrifice Antarctica to save the currently inhabited coastal regions and the cultural heritage that we have built and are building on our shores. It is about global metropolises, from New York to Shanghai, which in the long term will be below sea level if nothing is done," Levermann said in a statement.

"The West Antarctic Ice Sheet is one of the tipping elements in our climate system. Ice loss is accelerating and might not stop until the West Antarctic ice sheet is practically gone."

Researchers used computer simulations designed to predict future loss. The results confirmed previous research, suggesting even drastic cuts to greenhouse gas emissions may not be enough to stop the West Antarctic ice sheet collapsing.

They then turned to fixes that could help remedy the problem and avert a crisis. This led them to investigate interventions that might increase snowfall in the destabilized regions of the West Antarctic ice sheet.

"[W]e find that an awful lot of snow can indeed push the ice sheet back towards a stable regime and stop the instability," said co-author Johannes Feldmann.

"In practice, this could be realized by an enormous redisposition of water masses."

It would require trillions of tons of artificially-produced snowfall to lay an area the size of Costa Rica (or half the size of Iceland) – roughly 52,000 kilometers squared in total.

The researchers are keen to stress that this isn't a proposal, pointing to the scale of disruption – and energy – such a scheme would involve. The uplifting, desalinating, and heating of ocean water and powering of snow cannons would guzzle up so much energy it would require building over 12,000 high-end wind turbines. the study authors calculate.

"Putting up such a wind farm and the further infrastructure in the Amundsen Sea and the massive extraction of ocean water itself would essentially mean losing a unique natural reserve," said Feldmann.

"Further, the harsh Antarctic climate makes the technical challenges difficult to anticipate and hard to handle while the potentially hazardous impacts to the region are likely to be devastating."

The study authors explain their model simulations exclude many things that may slow down or exacerbate Antarctic ice melt, like ice shelf hydrofracturing triggered by atmospheric warming. It also relies on us sticking to the terms of the Paris Agreement and meeting the 1.5 °C limit.

"The apparent absurdity of the endeavor to let it snow in Antarctica to stop an ice instability reflects the breath-taking dimension of the sea-level problem," said Levermann.

Other imaginative engineering feats dreamt up to stop sea-level rise include a giant artificial wall built to prop up Antarctica's ice sheets.