According to a new report led by professor Tim Lenton from the University of Exeter’s Global Systems Institute, in collaboration with more than 200 researchers worldwide, Earth’s climate has already warmed enough that humans are at risk of triggering five global “tipping points” that could have disastrous effects on the planet.
If the world warms more than 1.5 degrees Celsius above pre-industrial levels, the likelihood of breaching these tipping points increases, as does the chance of crossing others, reported New Scientist.
“Triggering one tipping point could trigger another in a kind of dangerous domino effect,” Lenton said, as New Scientist reported.
The report, Global Tipping Points, was assembled by researchers in 26 countries from more than 90 organizations.
Lenton referred to a tipping point — a slight change in a system that causes drastic changes that are difficult to reverse or are even irreversible due to an intensifying feedback loop — as akin to leaning backwards in a chair.
The five tipping points laid out in the report are: the melting of the ice sheets in West Antarctica and Greenland; the rapid thawing of large swaths of Arctic permafrost; the slowing of the North Atlantic subpolar gyre; and tropical coral reef die-off.
“[T]hese tipping points in the Earth system could, in turn, trigger damaging tipping points in societies, things like food security crises, mass displacement and conflicts. Stopping these threats is possible, but it’s going to require urgent global action,” Lenton said, as reported by WION.
The North Atlantic subpolar gyre is an important circular ocean current associated with the Atlantic meridional overturning circulation (AMOC), New Scientist said. AMOC is a large system of currents that circulates water in a long cycle from north to south within the Atlantic Ocean, bringing warmth and nutrients to parts of the planet.
According to David Armstrong McKay, a research impact fellow at the University of Exeter, there is evidence that the subpolar gyre could slow down or stop sooner than AMOC.
“[The slowing of the subpolar gyre] could happen within about 10 years. It would have pretty major impacts across both sides of the Atlantic,” McKay said, according to New Scientist. “It would cause regional cooling and affect agriculture in Europe and North America, and change the patterns of extreme weather events.”
Manjana Milkoreit, who contributed to the report and is a postdoctoral researcher at the University of Oslo, said if we want to stop some of these tipping points, we need to do it right away.
“For some tipping points, we have a very short window for preventive action open right now which might close as soon as the 2030s,” Milkoreit said, as New Scientist reported. “We think that the prevention of Earth system tipping points should be the core objective of governance efforts because of the scale and severity of the threats that they represent, their cascading potential and the irreversibility of many tipping processes on relevant human timescales.”
The collapse of fisheries and the die-off of mangrove forests and seagrass meadows are some of the other tipping points.
The report points out that whether or not some systems have tipping points, how far off they are and what the potential impacts would be remains unclear.
Milkoreit emphasized that reducing and eliminating greenhouse gas emissions as quickly as possible is still the best way to limit global heating and reduce the chances of triggering these dangerous tipping points. Additional actions like stopping Amazon deforestation would also help, Milkoreit said.
“Even with a profound acceleration of action, some Earth system tipping points may be unavoidable,” Lenton pointed out. “But still there are things we can do to mitigate the risk they pose by reducing the vulnerability of people to the impacts coming from them.”
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