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The Greenland ice sheet may have reached a tipping point that puts it on an irreversible path to disappear completely.
The snowfall that normally replenishes Greenland’s glaciers each year can no longer keep pace with the melting ice, according to researchers at Ohio State University.
This means that the Greenland ice cap – the second largest mass of ice in the world – would continue to lose ice even if global temperatures stop rising.
In their study, published Thursday in the journal Nature, scientists looked at 40 years of monthly satellite data from more than 200 large glaciers that drain into the ocean across Greenland.
“What we found is that the ice flowing into the ocean far exceeds the snow that accumulates on the surface of the ice sheet,” said Michalea King, lead author of the study and researcher at the Byrd Polar and Climate Research Center at Ohio State University. , said in a press release.
The complete melting of the Greenland ice sheet could raise the sea level by 23 feet (~ 7 meters) by the year 3000.
If that happens, the ocean would engulf coastal cities around the world.
Greenland’s ice is already the world’s largest contributor to sea level rise. In the next 80 years alone, its current melt rate would add another 2.75 inches (6.9 cm) to the global level of the sea, according to a study published in December.
“The retreating glaciers have shifted the dynamics of the entire ice sheet into a constant state of loss,” said Ian Howat, glaciologist and co-author of the paper, in the statement.
“Even if the climate were to stay the same or even get a little colder, the ice cap would still lose mass.”
But that’s just one of the many tipping points on climate change that human activity could bring. There is still time to avoid irreversible paths to further calamities.
There are more points of no return
The amount of ice lost by Greenland each year has steadily increased over the past two decades. Before 2000, researchers found that the ice sheet had an equal chance of gaining or losing mass every year.
But in the climate of the past 20 years, it will only gain mass once every 100 years, the researchers found.
Greenland dumped an unprecedented amount of ice and water into the ocean in the summer of 2019, when a heat wave from Europe swept through the island.
The ice cap lost 55 billion tonnes of water in five days – enough to cover the state of Florida with nearly five inches of water.
Melting causes more melting, as the water that collects through the ice sheet absorbs more sunlight and further heats everything around it. That’s why tipping points like Greenland’s accelerate ice loss so much.
Rising global temperatures and certain human activities can also cause tipping points in other parts of the world.
In the Arctic, melting ice exposes permafrost – frozen ground that releases powerful greenhouse gases when it thaws. If warming thaws enough permafrost, the released gases will trap heat faster than fossil fuel emissions from humans.
In the Amazon rainforest, humans have been cutting and burning trees for years, allowing moisture to escape the ecosystem. Sufficient deforestation could trigger a process called “dieback,” in which the rainforest withers, burns and becomes a savanna-like landscape, releasing up to 140 billion tonnes of carbon into the atmosphere.
Last year, leading rainforest scientists warned the Amazon was “teetering on the edge” of that threshold.
Yet scientists say switching to less carbon-intensive forms of energy, like solar power, and reducing unsustainable logging and mining can help us avoid these disasters.
Even for the Greenland ice sheet, the future holds more tipping points – degrees of collapse that will accelerate the melting of glaciers even more. Limiting global warming could delay these tipping points and give the world more time to prepare.
“We are past the point of no return, but there is obviously more to come,” Howat told CNN.
“Rather than being a single tipping point where we went from a happy ice cap to a rapidly collapsing ice cap, it’s more of a staircase where we fell from the first step, but there is has many more steps to go down into the pit. “
This article was originally published by Business Insider.
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