Warming of the Southern Ocean threatens 60% of Antarctic ice sheets
An international team of scientists, led by researchers from Université Grenoble Alpes and the CNRS, warns that sixty percent of the floating ice sheets around Antarctica are at risk of disappearing in the long term. VUB researcher Christoph Kittel also contributed to the study published in the scientific journal Nature.
These ice shelves are of great importance because they act as a natural brake on the land ice of the Antarctic ice sheet. They slow down the sliding of the ice into the ocean and thus limit the rise in sea level. According to the researchers, if greenhouse gas emissions remain high and the Earth warms by an average of twelve degrees Celsius by the year 2300, the ocean will warm significantly. This warming will cause intense melting at the bottom of the ice sheets, causing them to disappear over time. Their supporting effect will then also disappear, which will drastically accelerate sea level rise.
According to lead author Clara Burgard, affiliated with Université Grenoble Alpes and the CNRS, the results leave no doubt that the future of Antarctica depends directly on our current climate policy. Burgard emphasises that "the future of Antarctica is literally in our hands, because what we do now to limit emissions will determine whether most ice sheets can continue to exist or disappear forever."
Antarctica's weak spot
The floating ice shelves are the Achilles heel of the Antarctic ice sheet. They temporarily hold back the land ice, but are extremely sensitive to changes in air and sea temperature. Their disappearance would greatly accelerate sea level rise, posing a major long-term risk to coastal areas worldwide.
The researchers used a new analysis method that takes into account uncertainties in climate and ice processes, such as ice breaks and the calving of icebergs. This enabled them to estimate when certain ice shelves will almost certainly no longer survive.
If we do nothing
The study shows that if greenhouse gas emissions continue to rise, 26 of the 64 large ice sheets will disappear by 2150, a scenario that corresponds to a world that is approximately eight degrees warmer than in the pre-industrial era. By 2300, warming could reach around twelve degrees, causing the loss of 38 ice sheets.
The main cause is the warming of the ocean, which is melting the ice from below beyond a critical point. When these natural support structures disappear, Antarctic land ice can flow into the sea much faster. According to the researchers, this could lead to a sea level rise of up to ten metres in the long term.
In a favourable scenario, in which global emissions fall rapidly and sharply and the temperature rise remains below two degrees, only one of the 64 ice shelves would disappear. Burgard says that ‘these results make it clear that our choices today about greenhouse gas emissions directly determine what Antarctica and our coastlines will look like in the future.’
The research shows that drastic emission reductions can still make the difference between preserving or losing most Antarctic ice sheets.
