Fresh alarm has been raised about the state of the climate after experts announced that ice-free Arctic summers are now unavoidable.
The polar region could be without sea ice in September as soon as the 2030s, according to the journal Nature. Researchers from South Korea, Canada and Germany examined satellite data and climate models from 1979-2019 to see how Arctic sea ice has changed. They found that ice loss will occur earlier than previously predicted – a decade sooner than the last assessment from the UN, which forecast an ice-free Arctic from the middle of the century.
The findings could be further evidence that the world is close to several major climate tipping points, some of which might have already been crossed. “We basically are saying that it has become too late to save the Arctic summer sea ice,” Professor Dirk Notz, from the University of Hamburg, who took part the study, told Bloomberg.
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What are the climate change tipping points?
The UN’s Intergovernmental Panel on Climate Change (IPCC) defines tipping points as “critical thresholds in a system that, when exceeded, can lead to a significant change in the state of the system, often with an understanding that the change is irreversible”. Even “small changes in global temperatures can kick off reinforcing loops that ‘tip’ a system into a profoundly different state”, said the climate non-profit news outlet Grist.
There are five climate tipping points that may have already been reached, according to a study published last year in the journal Science. These include the collapse of Greenland’s ice cap and the Gulf Stream in the north Atlantic, and the abrupt melting of permafrost. Other tipping points on the horizon include disruption to monsoon and tidal patterns and irreversible changes to the Amazon rainforest. The tipping points “can behave like a domino effect, with one making another more likely”, the study authors added.
When will the tipping points be crossed?
Five tipping points “may already have been passed due to the 1.1C of global heating caused by humanity to date”, said The Guardian.
At heating of 1.5C above pre-industrial levels, “four of the five tipping points move from being possible to likely”, added the paper, and five additional tipping points become possible, “including changes to vast northern forests and the loss of almost all mountain glaciers”. In total, researchers have found evidence for 16 tipping points, with the final six requiring global heating of at least 2C to be triggered.
What would the effects be?
The effects could be drastic and wide-ranging, with an increased risk of droughts and rising sea levels, according to Earth.org.
Thawing permafrost would see more carbon dioxide and methane released into the atmosphere, and coral systems could undergo irreversible bleaching and physical destruction. A slowdown of the AMOC (the Atlantic Meridional Overturning Circulation – a large system of ocean currents) would lead to more winter storms in Europe and weaker summer monsoons in Asia. Increasing heat levels could cause oceanic plankton to release carbon dioxide rather than absorb it, according to a study published this week in Functional Ecology.
As for an ice-free Arctic, “expect the shipping, oil and gas and minerals corporations to descend like vultures”, Bill McGuire, Professor Emeritus of Geophysical and Climate Hazards at University College London, told The Independent.
Does everyone agree?
Some experts say the idea of climate tipping points is unhelpful and unscientific. Take Greenland’s ice sheet, for example. Some modelling suggests that it does not have a tipping point, as “increased snowfall over Greenland’s remaining ice” could allow the ice sheet to stabilise, said Grist.
How long the tipping points take to materialise is also up for debate, with estimates ranging from decades to centuries. The idea of tipping points might also put some people off taking action. Seaver Wang in The Breakthrough said that “the feeling that the planet is just years away from sliding beyond a catastrophic point of no return invites unproductive fatalism”. But the idea of an “imminent climate cliff” also makes sensible long-term planning less likely.
Is it too late?
“The only way we’ll avoid an accelerating slide into civilisational collapse is by transforming [our] suicidal way of life,” said Jonathon Porritt, one of Britain’s most respected environmentalists.
But while there are “grounds for grief”, Dr David Armstrong McKay, from the University of Exeter, told The Guardian, “there are also still grounds for hope”.
The fate of the climate is still in our hands as long as governments take seriously their commitments to keep the global temperature rise below 1.5C. “There is no tipping point beyond which Mother Earth wrestles control of the whole climate system away from human beings and proceeds to punish us for our sins,” said Wang in The Breakthrough.
