The hidden ocean beneath Antarctica’s largest ice shelf may be the continent’s Achilles’ heel and a major driver of higher sea levels than scientists once expected.
What happened?
For the first time, researchers have collected long-term measurements from deep beneath the Ross Ice Shelf, a floating ice sheet about the size of France that helps hold back the polar ice caps.
For more than four years, scientists have tracked ocean temperature, salinity and currents under the ice using instruments placed through boreholes.
Their study, published in the Journal of Geophysical Research: Oceans, shows that ocean cavities beneath the ice are more dynamic than previously thought. Rather than remaining stable, the water undergoes seasonal changes, including deeper, supercooled currents and currents that transfer heat to the ice from below.
Even a slight rise in ocean temperatures can dramatically accelerate melting at the base of ice shelves, a process scientists call basal melting.
Why is this finding concerning?
Ice shelves act like barriers, slowing the movement of glaciers toward the ocean, according to the National Snow and Ice Data Center. Eventually, thinning glaciers can flow more freely into the ocean, which could contribute to global sea level rise.
Basal melting is troubling because it is largely invisible and is responsible for much of the ice shelf loss. Tracking surface ice loss is relatively easy, but melting from below is difficult to monitor without customized equipment and can destabilize large-scale ice systems before significant collapse occurs.
When sea levels rise, it can threaten coastal cities, infrastructure and freshwater supplies. It would also increase the risk of flooding and disease for millions of people. When polar ice disappears, it disrupts global ocean circulation, which plays an important role in regulating weather patterns and marine ecosystems.
These changes are driven by human activities, particularly the burning of oil, gas and coal, which trap heat in the atmosphere and oceans.
Previous reports have shown that the Ross Ice Shelf is sliding at a measurable rate every day, while other studies have warned of increasing amounts of “slush” on top of the ice shelf — a waterlogged layer that produces nearly three times the amount of meltwater as solid ice because it absorbs more heat.
What is being done about these situations?
Expanded ocean monitoring is critical to improving climate models and predicting future risks.
Initiatives such as NASA’s Earth System Explorer program aim to enable similar space science research and monitoring tools to study how greenhouse gases and other factors are eroding the Earth.
In the long term, reducing reliance on oil, gas and coal remains one of the most effective ways to slow ocean warming. Switching to clean energy, protecting ocean ecosystems, and discussing these issues with family and friends can help keep the oceans cool.
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