According to recent estimates, about a third of the ice shelves holding back massive glaciers in Antarctica are at risk of collapsing if the world fails to take appropriate action on climate change.The ice shelves that circle the continent are vulnerable to meltwater on their surface, which causes cracking and disintegration of the ice, a process known as hydrofracturing.
According to computer modeling by Ella Gilbert of the University of Reading in the United Kingdom and Christoph Kittel of the University of Liege in Belgium, if the planet warms by 4°C above pre-industrial levels, 34% of the continent’s ice shelves would have meltwater on their surface, indicating that they are at risk of collapsing.
If the temperature increases are checked at 2°C, the figure drops to 18 percent. The global economy is currently on track to increase by 2.9° C
, but if implemented it will reduce climate plans and the net zero targets to 2.1° C.
“Warming to 2°C means half the ice shelf area is at risk of collapsing. That is the message: the less the warming the better,” says Gilbert.
She and Kittel used a climate model with a far higher resolution than previous studies, with grid squares measuring 35 kilometers rather than hundreds of kilometers. It also more accurately reflects cloud physics, which is important because how much ice loss is replaced by snowfall affects estimates of the region at risk of collapse. In a 4°C warmer climate, melting outweighs increased snowfall, resulting in a significant gap between the 2°C and 4°C rise scenarios.
One of the most vulnerable areas was discovered to be the Larsen C ice shelf on the east coast of the Antarctic Peninsula, where a massive iceberg broke off in 2017.
“This study shows melting at the ice shelves’ surface will spreads southwards to parts of the continent where huge reservoirs of inland ice may lose their protective barrier. If that happens, we can expect rapid increases in sea level rise along every coastline of our planet,” says Andrew Shepherd at the University of Leeds, UK, who wasn’t involved with the paper.
The study doesn’t specify how much sea level rise would occur if ice shelves collapsed and the glaciers behind them were released. “My gut instinct is for 4°C, it could theoretically contribute tens of centimetres if they did collapse,” Gilbert says. Avoiding a ten-centimetre increase in sea level will put 10 million people in the world at risk of flooding.
Helene Seroussi, who was not part of the research team at NASA’s Jet Propulsion Lab, says that the major progress of the study is with a higher-resolution model. While investigations identify hydrofractured ice shelves, Seroussi says further analysis of how individual ice shelves – the dynamic stress scheme – move around is necessary to identify which ones will collapse.
Source: New Scientist