At the far edge of the planet, where the frozen southern continent meets the open ocean, a slow unraveling is gathering pace that a new study in Nature now places among the great turning points of the climate system. The sea ice that forms each year around Antarctica has shrunk well beyond the range the planet has known for centuries, and the researchers describe the change as more sudden and less reversible than the retreat of ice in the Arctic. Their evidence, drawn from satellites, ice cores and old ship logs, shows a loss that feeds on itself, as less ice means more absorbed heat, more dis
Rapid Antarctic Sea Ice Loss May Be a Climate Tipping Point, Nature Study Warns
Even if we stabilise the climate, we are committed to still losing Antarctic sea ice
Mark
Why is this paper getting attention? We already knew sea ice was shrinking.
Mimi
Because it frames the recent drop as a regime shift. The ice extent is far below anything in the natural variability of past centuries, according to the ice cores, logbooks and observations they combined.
Mark
And the Arctic comparison?
Mimi
The authors say that in some respects Antarctic loss is more abrupt, non-linear and potentially irreversible than the Arctic's. That's a notable claim.
Luke
Worth noting the wording, though: "in some respects" and "potentially." The paper isn't saying it's proven irreversible across the board.
Mark
What makes it self-reinforcing?
Mimi
Several loops. Less ice reflects less sunlight, so more heat is absorbed. The overturning circulation likely weakens. Penguins, krill and phytoplankton suffer, and phytoplankton help pull carbon from the air.
Luke
Some of that is stated as probable, like the circulation weakening. And Abram's line that it "may actually be" a tipping point is hedged. It's a warning, not a confirmed threshold crossing.
Mark
Does cutting emissions still matter?
Mimi
Yes, it reduces the risk, the study says. But it may not prevent major change, and Abram says loss would continue for centuries even with a stable climate.
Luke
The article gives no figures for how much ice, how fast, or what sea level rise to expect. Those details aren't in this reporting.
O Pulso
- Antarctic sea ice has slipped far outside the natural range of the last several centuries, and the drop is arriving faster than many expected.
- Each lost patch of ice reflects less sunlight, so the ocean absorbs more heat and the loss accelerates on its own.
- Emperor penguins, krill and the phytoplankton that pull carbon from the air are all being pushed toward decline by the shrinking ice.
- Scientists are mapping the changes against ice cores and ship logbooks, searching for the thresholds where the process becomes irreversible.
- Even if emissions are curbed, the ice may keep retreating for centuries, leaving the central question how much damage can still be limited.
At the far edge of the planet, where the frozen southern continent meets the open ocean, a slow unraveling is gathering pace that a new study in Nature now places among the great turning points of the climate system. The sea ice that forms each year around Antarctica has shrunk well beyond the range the planet has known for centuries, and the researchers describe the change as more sudden and less reversible than the retreat of ice in the Arctic. Their evidence, drawn from satellites, ice cores and old ship logs, shows a loss that feeds on itself, as less ice means more absorbed heat, more disturbed currents and fewer living things at the base of the food web. The paper's hardest lesson is that cutting emissions still matters, yet even a stabilised climate may not spare the south the losses already set in motion.
A paper published in the journal Nature has delivered a sobering verdict on the frozen south. Researchers say the rapid loss of Antarctic sea ice may be a tipping point for the global climate, with effects that reach into sea levels, ocean currents and marine life, and that may not be reversed.
The team, led by Nerilie Abram, set out to show how the warming of Antarctica's surroundings interlocks across the system. To judge how far the present decline has strayed, they combined modern observations with ice cores and ship logbooks, building a picture of sea ice stretching back much further than satellites allow. Their conclusion was that a regime shift has pushed the ice far below anything seen in past centuries, and that the change is more abrupt and potentially irreversible than in the Arctic.
The mechanisms reinforce one another. Less ice reflects less sunlight, so more warmth is absorbed, while the ocean circulation that distributes heat and nutrients weakens. Wildlife is already paying the price: emperor penguins that breed on the ice, krill that feed beneath it, and the phytoplankton that draw carbon from the atmosphere are all threatened.
Abram, now chief scientist at the Australian Antarctic Division, says the ice may be one of the Earth's true tipping points, and that once it begins to go, a self-perpetuating process takes hold. Cutting emissions would lower the risk, the paper says, but may not prevent major change. Even a stabilised climate would leave the ice declining for centuries. The study's remaining question is not whether all the damage can be avoided, but how much of it can still be contained.
A paper published in the journal Nature has set out a stark reading of what is happening at the bottom of the world: the rapid loss of Antarctic sea ice may amount to a tipping point for the global climate, with consequences including sea level rise, altered ocean currents and losses of marine life that cannot be reversed.
The study set out to describe, in more detail than has been done before, how the effects of global warming on Antarctica interlock. Its authors wrote that evidence is emerging of rapid, interacting and sometimes self-perpetuating changes in the Antarctic environment. The continent sits at the planet's South Pole and is frozen year-round, but the ice that forms around it is the part now in retreat.
To put recent years in context, the researchers drew on three kinds of record: modern observations, ice cores, and ship logbooks. Together these let them chart long-term changes in the area covered by sea ice and measure the recent rapid decline against a much longer baseline.
Their conclusion was blunt. A regime shift, they wrote, has pushed Antarctic sea-ice extent far below its natural variability of past centuries. In some respects, the paper said, this is more abrupt, non-linear and potentially irreversible than the loss of sea ice in the Arctic, at the North Pole.
Lead author Nerilie Abram said the changes are cascading through the ecosystem and in some cases amplifying one another. The mechanisms are specific. A smaller expanse of ice reflects less solar radiation, so the planet absorbs more warmth. The loss is also likely to speed up a weakening of the Antarctic Overturning Circulation, an ocean-spanning current that distributes heat and nutrients and helps regulate weather.
Wildlife is already affected. Emperor penguins, which breed on the ice, and krill, which feed beneath it, are increasingly harmed by its disappearance. The study added that warming surface water will further reduce phytoplankton populations, which draw vast quantities of carbon out of the atmosphere.
Abram, a former professor at the Australian National University and now chief scientist at the Australian Antarctic Division, said Antarctic sea ice may actually be one of those tipping points in the Earth's system. Once the ice starts to go, she said, a self-perpetuating process is set in train.
The paper's message on emissions is a qualified one. Reining in global carbon dioxide emissions would reduce the risk of major changes in the Antarctic, it said, but may still not prevent them. Abram put the long view plainly: even if the climate is stabilised, the world is committed to continued loss of Antarctic sea ice over many centuries to come. The question the study leaves is how much of the damage can still be limited, not whether it can all be avoided.
Citações Notáveis
Antarctic sea ice may actually be one of those tipping points in the Earth's system.— Nerilie Abram, lead author
Once we start losing Antarctic sea ice, we set in train this self-perpetuating process.— Nerilie Abram, lead author
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Climate & Environment