This is because the latest climate model projections presented in the 6th assessment report of the Intergovernmental Panel on Climate Change (IPCC) do not agree on how quickly the major ice sheets will respond to global warming, they said.
The study, published in the journal Nature Communications, noted that melting ice sheets are potentially the largest contributor to sea level change, and historically the hardest to predict because the physics governing their behaviour is notoriously complex.
“Moreover, computer models that simulate the dynamics of the ice sheets in Greenland and Antarctica often do not account for the fact that ice sheet melting will affect ocean processes, which, in turn, can feed back onto the ice sheet and the atmosphere,” said Jun Young Park, PhD student at the IBS Center for Climate Physics and Pusan National University, South Korea and first author of the study.
Using a new computer model, which captures for the first time the coupling between ice sheets, icebergs, ocean and atmosphere, the researchers found that an ice sheet/sea level run-away effect can be prevented only if the world reaches net zero carbon emissions before 2060.
“If we miss this emission goal, the ice sheets will disintegrate and melt at an accelerated pace, according to our calculations. If we don’t take any action, retreating ice sheets would continue to increase sea level by at least 100 cm within the next 130 years,” said Professor Axel Timmermann, co-author of the study and Director of the IBS Center for Climate Physics.
“This would be on top of other contributions, such as the thermal expansion of ocean water,” Timmermann said. Ice sheets respond to atmospheric and oceanic warming in delayed and often unpredictable ways. Previously, scientists have highlighted the importance of subsurface ocean melting as a key process, which can trigger runaway effects in the major marine based ice sheets in Antarctica.
“However, according to our supercomputer simulations, the effectiveness of these processes may have been overestimated in recent studies,” said Professor June Yi Lee from the IBS Center for Climate Physics and Pusan National University and co-author of the study.
“We see that sea ice and atmospheric circulation changes around Antarctica also play a crucial role in controlling the amount of ice sheet melting with repercussions for global sea level projections,” she added.
The study highlights the need to develop more complex earth system models, which capture the different climate components, as well as their interactions.