‘Worrying’ discovery beneath Antarctic ice sheets

Small changes in ocean temperatures are having a very big impact on the melting of ice.

A red vehicle moving along the West Antarctic Ice Sheet.
The West Antarctic Ice Sheet (pictured) has experienced widespread melting. Source: David Vaughan, BAS

Deep beneath the frigid surface of Antarctica, researchers have detected a “worrying” change.

While it’s long been known that melting ice caps are causing sea levels to rise, researchers have discovered a previously unknown occurrence that could be speeding up the process.

The problem could directly impact the 900 million people who live in low-lying coastal cities around the world. So efforts to protect these towns from coastal inundation may need to be rolled out faster than previously thought.

Related: Ice shelf half the size of Canberra breaks off from Antarctica

The British Antarctic Survey (BAS) found the problem occurs where ice sheets that rest on land meet the sea. These stretches, known as “grounding zones”, are usually several kilometres long and known to be sensitive to atmospheric and oceanic change.

It’s here that increasingly warm seawater caused by climate change is accelerating the creation of new cavities in the ice. These holes allow more water to tunnel from the sea into the space between the ice and the ground it rests on. This lubricates the ice bed above and hastens the pace with which it melts back into the sea.

“A very small change in ocean temperature can cause a very big increase in grounding zone melting, which would lead to a very big change in flow of the ice above it,” BAS ice dynamics researcher Alex Bradley said.

Grounding zones across Greenland.
Warming water is effecting grounding zones across Greenland (pictured) and Antarctica. Source: Getty

Changes in this region are responsible for a lot of the water that enters the ocean and causes sea level rises. The BAS says the find illustrates a "new and worrying way" that large ice sheets melt.

Bradley is concerned the impact of warming waters on grounding zones in both Antarctica and Greenland have not yet been accounted for in climate modelling by the Intergovernmental Panel on Climate Change (IPCC).

“Our projections of sea level rise might be significant underestimates,” he warned.

The findings have been published in the journal Nature Geoscience.

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