Sep 24 2020
A group of climate scientists has reported that upcoming ice-sheet melt is anticipated to have a major impact on the global climate. This finding was based on the latest climate modeling study that examined the effects of accelerated ice melt from the Antarctic Ice Sheet (AIS) on the upcoming climate.
Antarctica seen from the R/V Laurence M. Gould. Image Credit: Dan Lowenstein, © WHOI.
Shaina Sadai, the study’s first author and graduate student from the University of Massachusetts Amherst (UMass Amherst), along with Alan Condron from the Woods Hole Oceanographic Institution, Rob DeConto from UMass Amherst, and David Pollard from Pennsylvania State University, has reported the details in the Science Advances journal.
The researchers’ study predicts how upcoming climate conditions can change under low and high greenhouse gas emissions conditions while accounting for expedited melting of the AIS.
Although investigators had known for a long time that upcoming meltwater input from the Antarctic will impact the Southern Ocean and global climate, ice-sheet processes are not currently included in a majority of the advanced climate prediction simulations, stated Sadai.
Along with her collaborators, Sadai reported that their new modeling with the added ice melt data exposes the interacting processes.
In this study, Sadai’s task was to introduce accelerated AIS melting as well as icebergs into simulations of the Earth’s upcoming climate. One major step was to add the details of when and where the meltwater will enter the ocean.
We found that future melt water coming off Antarctica leads to huge amounts of thick sea ice around the continent. With higher greenhouse gas emissions, the ice sheet melts faster, which in turn leads to more freshwater flowing into the ocean and more sea ice production.
Shaina Sadai, Study First Author and Graduate Student, University of Massachusetts Amherst
All these sea ice productions and additional meltwater considerably slow down the rate of upcoming warming around Antarctica, reported the team—which is apparently welcome news. And most incredibly, the effects of climate are not simply limited to the Antarctic.
Condron, who was earlier at UMass Amherst, pointed out that the cooling effects are experienced throughout the world.
All that said, it's important to note that this is not a global 'cooling' scenario - average global temperatures would still be roughly 3 degrees Celsius warmer than today due to human greenhouse gas emissions, even with the cooling effects of this melt water on climate.
Alan Condron, Woods Hole Oceanographic Institution
Although atmospheric warming has slowed down, the deep sea waters around Antarctica warm faster in the researchers’ model. The reason is, the new sea ice prevents heat from escaping from the deeper waters to the air, explained Condron.
“The subsurface ocean waters warm by as much as one degree Celsius, which can increase melting below parts of the ice sheet. This could make the ice sheet more unstable and accelerate rates of sea-level rise beyond current projections,” added Condron.
Our results demonstrate a need to accurately account for meltwater input from ice sheets if we are to make confident climate predictions.
Shaina Sadai, Study First Author and Graduate Student, University of Massachusetts Amherst
Sadai emphasized that the delayed upcoming warming found by the team in the latest simulations may sound like good news. However, it must be remembered that serious warming and sea-level rise will continue to take place with persistent emissions of greenhouse gas, which will have an impact on both coastal communities and global ecosystems.
DeConto and Pollard added that the upcoming stability of the AIS and upcoming sea-level rise will be decided by which process wins out—that is, atmospheric cooling or ocean warming. The target of the researchers’ ongoing study is to answer this question.
Journal Reference:
Sadai, S., et al. (2020) Future climate response to Antarctic Ice Sheet melt caused by anthropogenic warming. Science Advances. doi.org/10.1126/sciadv.aaz1169.