While coastal populations all over the world are already bracing for rising sea levels, planning for measures to mitigate flooding and other possible damages has been quite difficult. This is because the latest climate projections disagree on how rapidly the world’s largest ice sheets will respond to global warming.
Now, a study published in the journal Nature Communications argues that an irreversible loss of the West Antarctic and Greenland ice sheets, along with a rapid acceleration of sea level rise, will be imminent if global temperatures rise more than 1.8°C above pre-industrial levels.
Although melting ice sheets are likely the largest contributor to sea level rise, their behavior has been hardest to predict since the physics governing their temperature-related changes is highly 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 study lead author Jun Young Park, a doctoral student in Climate Sciences at the IBS Center for Climate Physics and the Pusan National University in South Korea.
By using a groundbreaking computer model that captures the complex relations among ice sheets, icebergs, ocean, and atmosphere, the scientists discovered that a rapid acceleration of ice sheet melting and sea level rise could only be prevented if the world reaches net zero emissions by 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. This would be on top of other contributions, such as the thermal expansion of ocean water,” explained study co-author Axel Timmermann, the director of the IBS Center.
While in previous studies scientists have mainly stressed the importance of subsurface ocean melting, sea ice and atmospheric circulation changes around Antarctica also play major roles in controlling the amount of ice sheet melting and subsequent sea level rise. Thus, more complex earth system models that can capture the interactions between different climate components are urgently needed, along with new observational programs.
“One of the key challenges in simulating ice sheets is that even small-scale processes can play a crucial role in the large-scale response of an ice sheet and for the corresponding sea-level projections. Not only do we have to include the coupling of all components, as we did in our current study, but we also need to simulate the dynamics at the highest possible spatial resolution using some of the fastest supercomputers,” Timmermann concluded.
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