By 2060, New York may go under water: melting glaciers in Antarctica will raise sea level by 60 m

While US Secretary of State Anthony Blinken draws attention to climate change in the Arctic in meetings with other national officials, an even greater threat looms on the other side of the planet. The edition told in more detail Phys.

New research shows that it is Antarctica that can force the decision between the choices countries are making today regarding greenhouse gas emissions and the future survival of their coastlines and coastal cities, from New York to Shanghai.

This can happen much earlier than people think.

As the global temperature rises, the Arctic is losing ice, which directly affects people's lives and triggers feedback loops that contribute to even greater warming. But Antarctica plays a big role in sea level rise. There is enough ice on land to raise sea levels by more than 200 feet (60 meters) - about 10 times that of the Greenland ice sheet - and there are already signs of trouble.

Scientists have long known that the Antarctic ice sheet has physical fracture points beyond which ice loss can spiral out of control. A new study, published in the journal Nature, shows that Antarctica's ice sheet could reach a tipping point in just a few decades.

The results mean that the common argument for not cutting greenhouse gas emissions now and that technological advances can save us in the future is likely to fail.

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New research shows that if emissions continue at their current rates, by about 2060, the Antarctic ice sheet will cross a critical threshold and lead to a rise in world sea levels that is irreversible on human timescales. Removing carbon dioxide from the air at this point will not stop the ice from melting, and by 2100, sea levels could rise more than 10 times faster than today.

The tipping point

Antarctica has several protective ice shelves that fan out into the ocean in front of the continent's ever-flowing glaciers, slowing the flow of land-based glaciers into the sea. But these glaciers can thin and collapse when warmer water gets under them.

As ice shelves erode, they can expose tall ice cliffs that may not be able to resist on their own.

There are two potential instabilities at this point. Portions of the Antarctic ice sheet rest below sea level on bedrock that slopes inward towards the center of the continent, so warming ocean water can erode their lower edges, destabilizing them. Over water, melting surfaces and rain can open cracks in the ice.

When ice cliffs get too high to support themselves, they can collapse catastrophically, increasing the speed of ice flow into the ocean.

The study used computer simulations based on the physics of ice sheets and found that warming above 2 ° C (3,6 F) in Antarctica would cause a sharp jump in ice loss caused by the melting of the massive Thwaites Glacier. This glacier is the object of intensive research by scientists from the United States and Great Britain.

Other forecasts do not account for the instability of ice cliffs and generally give lower estimates of the rate of sea level rise. While much of the press coverage following the release of the new document has focused on the differences between the two approaches, both have come to the same fundamental conclusions: sea level rise can be dramatically reduced by fulfilling the goals of the Paris Agreement.

The disaster will not end in 2100

The new study by Robert DeConto, David Pollard and Richard Ellie is one of the few to go beyond this century.

It shows that if today's high emissions persist until 2100, sea level rise will explode, surpassing 2,3 inches (6 cm) per year by 2150. By 2300, sea levels will be 10 times higher than expected if countries adhere to the Paris Agreement targets. Warmer, softer ice sheets and a warmer ocean that retains warmth for centuries prevent the protective ice shelves of Antarctica from freezing again, leading to a completely different world.

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The vast majority of ways to implement the Paris Agreement assume emissions exceed targets to keep warming below 1,5C (2,7F) or 2C (3,6F), and then look to future technology advances to remove enough carbon dioxide from environment to lower the temperature again. The rest require a 50% reduction in global emissions by 2030.

While most countries, including the United States, Britain and the European Union, have set this goal as their primary target, current global policy will see a reduction of just 1% by 2030.

It's all about reducing emissions quickly

Some other researchers suggest that ice rocks in Antarctica may not collapse as quickly as in Greenland. But given their size and current rate of warming - much faster than on a historical scale - what if they decay faster instead?

As countries prepare to increase their Paris Agreement commitments ahead of the November meeting of the United Nations, Antarctica provides three important messages.

First, every fraction of a degree matters.

Second, letting global warming exceed 2 ° C is not a realistic option for coastal communities or the global economy. The reassuring prospect of technological fixes allowing later return to normal life is an illusion that will leave the coastline underwater with devastating economic consequences.

Third, today's policy must have a long-term perspective, because it can have irreversible consequences for the ice of Antarctica and the entire world. In recent decades, the focus of rapid climate change has been on the Arctic and its rich diversity of endangered cultures and ecosystems.

As scientists learn more about Antarctica, it becomes clear that it is this continent - without the constant presence of humans - that will determine the state of the planet on which today's children and their children will live.