Already, the melting sea ice in Antarctica has caused severe problems for the Southern Ocean. These include habitat loss and sea level rises as well as the intensity of storms. It turns out, however, that the situation can change at any time.
According to a new study published in the Proceedings of the National Academy of Sciences, the Southern Ocean’s surface is becoming saltier instead of fresher as Antarctic sea ice continues to disappear. The study’s authors claim that this pattern began in 2015. This trend is a shock to scientists and could spell trouble for remaining sea ice. Alessandro Silvano is a University of Southampton researcher and study author. According to a release, “saltier surface water allows deeper ocean heat to easily rise, melting the sea ice below.” It’s a vicious feedback loop. Less ice causes more heat which in turn leads to less ice.
Sudden Sea Change (
) Antarctica sea ice is melting and has done so for many decades. This melt makes the Southern Ocean’s surface fresher. The ice still present on the ocean floor has survived. A fresher surface of the ocean supports the remaining ice more than one that is saltier, as it traps heat from the depths and prevents the melting. The surface of the Southern Ocean has not been getting fresher, but has instead become saltier. This puts the remaining ice at greater risk.
Using data collected from submersible and satellite robots, study authors found that the Southern Ocean surface’s saltiness has increased since 2015. In the past few years, large swaths that would cover Greenland’s surface have disappeared. A single patch of ocean, the Maud Rise Polynya, has returned to the Weddell sea for the first since 1970s. It covers an area four times the size of Wales. The return of Maud Rise Polynya is a sign that the conditions in place are unusual, Silvano stated. If this low-ice, salty state persists, it will permanently change the Southern Ocean and the entire planet. These effects have already been felt worldwide: more intense storms, warming oceans, shrinking habitats of penguins, etc.
Is the current model of climate change up to scratch? Before the study was published, scientists believed that Antarctic sea ice could be preserved with warming for at least a short time. Although increasing temperatures will melt some ice, it is believed that the melting process would help protect the remaining ice by keeping the ocean surface fresher. The ocean would stratify, which will separate the warm waters in the deep ocean and the cool waters on the surface, stopping any melting of ice. According to a press release, Aditya Narayan, a research scientist at University of Southampton and another author of the study, said that previous projections had emphasized increased surface freshening, and stronger stratification of the ocean, both of which would have been able to support sustained sea ice coverage. The team says that further work is needed to identify the forces driving this change. The new study highlights that until these forces are determined, there will be some surprises with climate change. These surprises are important to monitor and integrate into the current climate models. According to a press release, “the new findings indicate that our understanding of climate change may not be sufficient to accurately predict the future,” Alberto Naveira Garabato is another author of the study and a Professor at the University of Southampton. It is therefore imperative that we continue to monitor the system with satellites and on-site monitoring, in order to better understand recent and future changes.
Sources for Articles
Discovermagazine.com writers use high-quality peer-reviewed sources and studies for their articles. Our editors check for accuracy, scientific standards and editorial standards. The sources for this article are listed below:
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PNAS. Science Advances: Satellites reveal a new southern ocean state with rising surface salinity and declining sea ice.
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Ekman Driven Salt Transport As A Key Mechanism For Open Ocean Polynya Forming At Maud Rise.
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Communications Earth & Environment. The Regional Emperor Penguin population declines exceed modelled projections
Sam Walters, a Discover journalist, covers archaeology and paleontology as well as ecology, evolution, and other topics. Sam Walters studied journalism at Northwestern University, Evanston, Illinois, before joining Discover as assistant editor in the year 2022.
