The edge of A-68, the iceberg the calved from the Larsen C ice shelf in July 2017.
Photo: NASA/Nathan Kurtz

To quote from Vanilla Ice’s 1990 smash hit, I want to talk about “ice ice baby.” The lowdown isn’t too uplifting: glaciers are melting at alarming levels across the planet, chunks of ice bigger than the state of Delaware are breaking off into the ocean, and projections show at least 2 feet of sea level rise by the end of the century. So, to borrow from Vanilla Ice’s prophetic song again: “Will it ever stop?”

One of the keys to answering this question lies in the frozen wasteland at the bottom of our planet. Antarctica contains something like 6.5 million cubic miles of ice, which, if melted, could raise global sea level by almost 200 feet! I don’t need to tell you how bad that would be for the 40% of the world’s population that lives within 60 miles of the coast.

So, the critical question for many years has been is Antarctica melting? While this might sound easy to answer, it’s proven tricky to predict how ice sheets respond to a warming climate. In fact, for many years the Intergovernmental Panel on Climate Change, which is the leading scientific body investigating climate change, thought that a warming climate would actually mean more ice in the poles. Satellite data has helped correct this narrative in recent years, with most of the scientific community agreeing that Antarctica is in fact losing ice. And now, a new report from the UK Centre for Polar Observation and Modelling provides the first complete mapping of Antarctica’s glacial retreat, showing that warm ocean water circulating beneath glaciers’ floating edge is melting the massive ice sheets. The study, published today in Nature Geoscience, details how over 550 square miles of ice were melted between 2010 and 2016.

Map showing rates of grounding line migration and their coincidence with ocean conditions around Antarctica between 2010 and 2016 (seabed temperatures: Locarnini et al., 2013. World Ocean Atlas 2013, Volume 1: Temperature. S. Levitus, Ed., A. Mishonov Technical Ed.; NOAA Atlas NESDIS 73, 40 pp.). Grounding line locations are from Rignot et al., 2013, Science 341 (6143), pp. 266-270.
Graphic: Hannes Konrad et al, University of Leeds

“Whenever you don’t map something in its entirety, somebody can always say ‘ah, but it might be advancing in another location,’ so this study closes that gap, making it clear that [Antartica ice] isn’t advancing,” said the study’s co-author Andrew Shepherd, from the School of Earth and Environment at the University of Leeds. “We’ve mapped 16,000 kilometers around the ice sheet, and seen a net overall retreat; in some parts of Antarctica, more than a fifth of the glaciers are retreating.”

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The ice in Antarctica isn’t melting from the top down, like it is in Greenland, but rather it’s melting from the bottom, where the ice meets the sea. As the temperatures increase in the ocean, warmer water works away at the ice. The problem, explained Shepherd, is that the place where glacial ice meets the sea (called the grounding line) is incredibly hard to reach, being 1-2 kilometres below sea level in a frigid, dark and cold environment.

Cartoon illustrating how horizontal motion of glacier grounding lines is detected usingsatellite measurements of their elevation change
Graphic: Hannes Konrad et al, University of Leeds

Shepherd and his colleagues were able to track the movement of Antarctica’s grounding line by using European Space Agency’s CryoSat-2 research satellite. By applying an understanding of glacier and sea floor geometry and a bit of math (Archimedes principle of buoyancy) the researchers were able to calculate the retreat in the grounding line across huge swaths of the country. The result is the first ever complete map detailing how the continent’s grounding line is shifting.

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“Our study provides clear evidence that retreat is happening across the ice sheet due to ocean melting at its base, and not just at the few spots that have been mapped before now,” said the study’s lead author, Hannes Konrad from the Alfred Wegener Institute. “This retreat has had a huge impact on inland glaciers, because releasing them from the sea bed removes friction, causing them to speed up and contribute to global sea level rise.”

So, what do these findings mean for sea level rise? While it’s still not totally clear, the fact that Antarctica’s grounding line is retreating is certainly not good news. A study published in the Proceedings of the National Academy of Sciences earlier this year found that accelerated melting in Greenland and Antarctica means that by 2100, the world’s oceans will be at least 60cm (2ft) higher than present. Other computer forecasts suggest that if emissions continue at their current, stupidly-high levels, huge chunks of Antarctica could break up, and lead the oceans to rise six feet or more by the end of this century.

This doesn’t have to mean the end of the world. Through proper adaption (seawalls, dams, canals, flood plains and pump systems) and mitigation (curbing emissions ASAP), the worst impacts of sea level rise can be avoided. Of course, the first step needs to be accepting that climate change and sea level rise are problems, and Trump doesn’t seem like the best person to prepare the U.S. for the rising tide.

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“We have to stop disagreeing about the things that we do know in terms of climate change, and quit using this “debate” as an excuse for not doing anything,” said Shepherd. “And we have to continue to convince people to think about generations in the future, rather than what’s happening today.”

Or, in Vanilla Ice’s words, all we have to do is “Stop! Collaborate and listen.”