A new study published in the ‘Nature’ journal has shown how Antarctica is moving towards a climate tipping point that has global consequences. The new research led by Robert DeConto, David Pollard and Richard Alley refocuses the attention on Antarctica and the impact it has on climate change.

Previous studies on global warming and the effects of greenhouse gases had set the Arctic region in front and centre trying to understand what the immediate consequences are. It is true that the Arctic is losing ice with the global temperature rise. This puts the lives of people who live in the region at great risk.
Towards this backdrop, the new study puts Antarctica as a force to reckon with. Unpopulated by humans, this gigantic mass of frozen water has got enough land ice to raise sea levels across the globe by more than 60 meters. As it turns out, Antarctica is reaching a critical tipping point in a few decades and it has the potential to overrun our current estimations.

What is this tipping point?

Antarctica has a lot of protective ice sheets, that keeps tall larger blocks of ice in place. These sheets act as a barrier and slow down the flow of glacial ice from the land to the sea. The more isolated the glacial ice remains lower will be their rate of melting.

As global ocean temperature rises, warmer water makes its way into the Antarctic and comes into contact with the protective sheets of ice. The sheets of ice melt, weakening it. Since these sheets are grounded on an inward sloping bedrock under the sea level, the melting results in a downward retreat of these sheets.

Illustration shows how warming water can get under glaciers and destabilize them

As a result ice cliffs which relied on the support of the protective ice sheets destabilizes and run the risk of toppling down. Surface melting and rainwater will then fracture these larger blocks into smaller chunks. The net result is a cascading set of events that accelerates the rate of melting of ice.

In the study, the researchers used a computer model to simulate the effects of warm water on the physics of these protective ice sheets. They inferred that a temperature rise that exceeds 2-degree Celcius can trigger ice loss in the Thwaites Glacier. This glacier has enough water to drain an area the size of Florida or Britain.

The study also shows us that if today’s emission rates continue well through to the year 2100, we will be looking at an explosive sea level rise (more than 6 cm per year by 2150). When accounted for the effect of protective sheets in the Antarctic region, the researchers state that by 2300 sea level would be ten times higher than the levels expected by the Paris Agreement (If all countries meet their goals).

Challenges before us

Almost all research in the field agrees to the point that the magnitude of rising sea level can be controlled to a good extent by meeting the Paris Agreement targets. But that doesn’t mean the approach is perfect. The agreement itself expects to have an overshoot of emissions and bets on future technologies to remove carbon dioxide from the atmosphere. The problem here is that once the events are set in motion they are irreversible. It is impossible to cool down a warm ocean fast, and we cannot reverse the weakening of protective ice sheets.

What can we do?

We should be focusing our attention on reducing emissions as fast as we can. Every fraction of degree matters. Even a slight overshoot from the projected 2-degree Celcius warming puts our coastal communities at great risk. Finally, the policies of today must take a larger view and must take into account what is happening in Antarctica.

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