Antarctic Climate Emergency
An Imminent Peril to Coastal Cities & People Everywhere
Concerns about the climate crisis mostly focused on the Arctic, bleaching coral reefs around the globe, fires in the Amazon, Australia, and California. Mostly neglected are changes in the Antarctic that pose a looming threat to 40% of the global population with consequences to people everywhere. In this time of climate crisis, Antarctica is the big icy elephant in the room: often overlooked, but far too large to ignore. Scientists have long known that the Antarctic ice sheet has physical tipping points, beyond which ice loss can accelerate out of control. This southern continent holds enough land ice to raise global sea levels by more than 60 metres if melted– imagine a submerged New York City, San Francisco, Tokyo, Shanghai, Singapore, Maldives. We are already seeing signs of trouble.
According to a new study published in the journal, Nature, Antarctica is on track for a climate tipping point by 2060 (around the time today’s primary school children will be raising their families), with catastrophic melting if current carbon emissions are not reduced swiftly, coupled with vital actions to restore and protect vital natural carbon-capturing systems. The research shows Antarctica may force a reckoning between the choices of countries to make today about greenhouse gas emissions and the future survival of their coastlines and coastal cities, from New York to Shanghai. This estimate is coming much sooner than everyone realizes.
The Arctic is losing ice as global temperatures rise, and that is directly affecting lives and triggering feedback loops that fuel more warming. But the big wild card for sea-level rise is Antarctica. The new study also revealed if emissions continue at their current pace, by about 2060, the Antarctic ice sheet will have crossed a critical threshold and committed the world to sea level rise that is no longer reversible on human timescales. By then, it will be far too late to reduce carbon dioxide emission, as at that point, any action won’t stop the ice loss, and by 2100, the sea level could be rising more than 10 times faster than today.
Antarctica has several protective ice shelves that fan out into the ocean ahead of the continent’s constantly flowing glaciers, slowing the land-based glaciers’ flow towards the sea. But those protective shelves are thinning, and many have broken off as warmer water moves in from beneath. As these enormous ice shelves break up, they expose towering ice cliffs that may not be able to stand on their own. There are two potential instabilities at this point. Parts of the Antarctic ice sheet are grounded below sea level on bedrock that slopes inward toward the centre of the continent. Warming ocean water can eat around their lower edges, destabilizing them and causing them to retreat downslope rapidly. Above the water, surface melt and rain can open fractures in the ice. When the ice cliffs get too tall to support themselves, they can collapse calamitously, accelerating the rate of ice flow to the ocean.
The study used computer modelling based on the physics of ice sheets and found that above 2o C of warming, Antarctica will see a sharp jump in ice loss, triggered by the rapid loss of ice through the massive Thwaites Glacier. This glacier drains an area the size of Florida or Britain and is the focus of intense study by U.S. and U.K. scientists¹. To put it into context, the planet is on track to exceed 2oC warming under countries’ current policies ². (Fig 1)
Ocean and polar scientists have three important messages to highlight about Antarctica. First, every fraction of a degree matters. Second, allowing global warming to overshoot 2oC is not an option for coastal communities or the global economy. The comforting prospect of technological fixes allowing a later return to normal is an illusion that will leave coastline metres underwater with devastating economic impacts. Thirdly, policies today must take the long view because they can have irreversible impacts on Antarctica’s ice and the world.
A fourth message is coming into sharp focus. The nature of Earth is governed by its unique fabric of life. It has taken four and a half billion years to shape barren rocks and water into the vibrant planet suitable for life as we know it and about four and a half decades to destroy the very systems that make our existence possible.
The living ocean drives climate and weather, shapes planetary temperature, governs Earth’s chemistry and provides home for the greatest abundance and diversity of life. Like trees and other vegetation, phytoplankton in the waters surrounding Antarctica are critically important to capturing carbon from the atmosphere, conveying carbon and nutrients to animals that in turn form the basis of vital food webs – and carbon sequestration.
The breaking up of an ice sheet in the Weddell Sea, Antarctica.
Photo by Michael AW.