New study finds 'rivers in the sky' could cause Antarctic Peninsula's biggest remaining ice shelf to collapse

Iceberg calved from Larsen C ice shelf in 2017.
Iceberg calved from Larsen C ice shelf in 2017. Photo credit: Getty Images

Scientists warn the biggest remaining ice shelf in the Antarctic Peninsula is at risk of total collapse due to 'rivers in the sky'.

Located in West Antarctica, the Antarctic Peninsula's ice shelves have been disintegrating, with an ice shelf of approximately 1200 square kilometres - slightly larger than Auckland - collapsing in March.

During March, Antarctica experienced a heatwave with temperatures in east Antarctica 40C above normal levels. While scientists don't know what role the high temperatures played in the fall of the ice shelf, they believe the heat rushed through a 'river in the sky', also known as an atmospheric river.

A river in the sky is a long plume of moisture that transports warm air and water vapour thousands of kilometres from the tropics across other parts of the Earth.

A new study called 'Intense atmospheric rivers can weaken ice shelf stability at the Antarctic Peninsula' found over 60 percent of the peninsula's calving events between 2000 and 2020 were triggered by atmospheric rivers.

The study found atmospheric rivers were causing extreme temperatures, surface melt, sea-ice disintegration and large ocean swells that are causing icebergs to break off the ice shelves.

"In the past 30 years, the large and dramatic collapses of the Larsen A, Larsen B, along with other major ice shelves along the Antarctic Peninsula (AP) raised fears for the fate of other ice shelves controlling the outgoing continental ice," the study stated.

The study said the biggest remaining ice shelf, Larsen C, is also at risk of total collapse.

"What our study found was that all these different aspects are actually caused by atmospheric rivers, especially the intense ones," one of the study's lead authors, Jonathan Wille from the Université Grenoble Alpes in France, told CNN.

If Larsen C were to collapse would make a critical contribution to rising sea levels.

"Ice shelves keep the glaciers that are on land behind them from flowing into the ocean," Wille told the outlet.

"And when these shelves disappear, there's nothing holding back those glaciers. Their velocity increases and starts flowing into the ocean. And that then directly contributes to sea-level rise."

A meteorologist at the British Antarctic Survey not involved in the study, John Turner, told the outlet most of an ice shelf's instability comes from melting from the bottom, also known as basal melt.

He said there are other reasons for the collapsing but agrees that atmospheric rivers may be "the nail in the coffin of some of these ice shelves".