Dire Warning About Global Sea Level Rise

Arctic Fjord Greenland Iceberg Sermilik Sea Ice

 An international team of scientists have concluded that an irreversible loss of the West Antarctic and Greenland ice sheets, and a corresponding rapid acceleration of sea level rise, may be imminent if global temperature change cannot be stabilized below 1.8°C, relative to the preindustrial levels.

Melting ice sheets are potentially the largest contributor to sea level change, and historically the hardest to predict because the physics governing their behavior is notoriously complex.

Prof. Axel Timmermann, Director of the IBS Center for Climate Physics, explained:

“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.”

Sea level rise contributions from the Antarctic and Greenland ice sheets, and maps of projected 2150 CE Antarctic ice sheet surface elevation following different greenhouse gas emission scenarios (SSP1-1.9, strong emission cuts; SSP2-4.5, medium emission cuts; SSP5-8.5, weak emission cuts). Image credit: Institute for Basic Science Jun-Young Park

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.

But says Prof. June Yi Lee from the IBS Center for Climate Physics and Pusan National University, “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.”

The study highlights the need to develop more complex earth system models, which capture the different climate components, as well as their interactions. Furthermore, new observational programs are needed to constrain the representation of physical processes in earth system models, in particular from highly active regions, such as Pine Island glacier in Antarctica.

Prof. Axel Timmermann said:

“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.”

Click on this link to access the study, Future sea-level projections with a coupled atmosphere-ocean-ice-sheet model, published in Nature Communications

Ice melange, a combination of ice shelf fragments, windblown snow and frozen seawater, can act as a glue to fuse large rifts in floating ice in Antarctica. Researchers at UCI and NASA JPL found that a thinning of the substance over time can cause rifts to open, leading to the calving of large icebergs. Image credit: Beck / NASA Operation IceBridge

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