The ‘points of no return’ for climate change may be much closer than we thought.
Climate tipping points — the “points of no return” beyond which key components of the Earth’s climate begin to irreversibly degrade — could be triggered by much lower temperatures than previously thought, with some tipping points potentially already reached. According to a new study, there are many more potential tipping points than scientists previously identified.
A tipping point in climatology is defined as a rise in global temperature beyond which a localized climate system, or “tipping element,” such as the Amazon rainforest or the Greenland ice sheet, begins to decline irreversibly. Once a tipping point is reached, that tipping element will experience runaway effects that will effectively doom it indefinitely, even if global temperatures fall below the tipping point.
Climate tipping points were first proposed in a 2008 paper published in the journal PNAS, when researchers identified nine key tipping elements that could reach such a threshold as a result of human-caused climate change. A team of researchers reassessed data from more than 200 papers on the subject of tipping points published since 2008 in the new study, which was published Sept. 9 in the journal Science. They discovered 16 major tipping points, almost all of which could reach the point of no return if global warming exceeds 2.7 degrees Fahrenheit (1.5 degrees Celsius) above preindustrial levels.
The Earth has already warmed by more than 2 degrees Fahrenheit (1.1 degrees Celsius) above preindustrial levels, and if current warming trends continue, it will warm by between 3.6 and 5.4 degrees Fahrenheit (2 and 3 degrees Celsius), according to the study’s authors.
“This puts Earth on track to cross multiple dangerous tipping points, which will be disastrous for people all over the world,” study co-author Johan Rockström, director of Germany’s Potsdam Institute for Climate Impact Research, said in a statement.
When the researchers reassessed the tipping points, they eliminated two of the original nine due to insufficient evidence — but then they discovered nine new ones that had previously been overlooked, bringing the total to 16, according to the study.
“Since I first assessed climate tipping points in 2008, the list has grown, and our assessment of the risk they pose has increased dramatically,” said co-author Tim Lenton, director of the Global Systems Institute at the University of Exeter in the United Kingdom and lead author of the original 2008 tipping points paper.
The researchers calculated the exact temperature at which each tipping element would be likely to pass its point of no return in the new study.
Their analysis revealed that five tipping elements — the Greenland and West Antarctic ice sheets, Arctic permafrost, tropical coral reefs, and a key ocean current in the Labrador Sea — are in the “danger zone,” which means they are on the verge of tipping.
Two of these danger zone tipping points, the Greenland and West Antarctic ice sheets, have already passed their lowest potential tipping points of 1.4 F (0.8 C) and 1.8 F (1 C) above preindustrial times, respectively, implying that these two systems may be beyond saving, according to researchers.
The other 11 tipping points are listed as “likely” or “possible” if warming exceeds 2.7 degrees Fahrenheit.
Previous estimates, such as the United Nations Intergovernmental Panel on Climate Change’s Sixth Assessment Report, published in three parts in 2021 and 2022, suggested that most major tipping points would be reached only if the Earth’s temperature rose above 3.6 degrees Fahrenheit, giving humanity more time to plan mitigation and adaptation strategies. However, the new study suggests that those tipping points may be closer than previously thought.
Researchers now fully understand the interconnectedness of tipping points, which could explain the accelerated timeline. Better climate models now show that the collapse of one tipping point increases the likelihood of another. For example, if Arctic permafrost melts due to rising temperatures, more carbon will be released into the atmosphere. This will raise surface temperatures on land and in the oceans, hastening the melting of major ice sheets and stressing coral reefs. In other words, tipping points are stacked like dominoes; if one falls, the others may quickly follow.
As a result, the researchers warn that we must drastically reduce our greenhouse gas emissions before this irreversible chain reaction begins.
“We must do everything possible to avoid crossing tipping points in order to maintain liveable conditions on Earth, protect people from rising extremes, and enable stable societies,” Rockström said. “Every tenth of a degree is significant.”
However, this will not be an easy task. To have a 50% chance of keeping global warming to 2.7 degrees Celsius, greenhouse gas emissions must be cut in half by 2030 and reach net zero by 2050, according to the researchers.
Given the slow pace of progress in combating climate change, this goal may appear unattainable. In fact, we appear to be moving backward in some ways; in June, the United States Supreme Court severely limited the federal government’s ability to regulate greenhouse gas emissions.
However, the study’s authors argue that such drastic changes could still be achieved through a different type of tipping point: a social one. According to the scientists, this is a theoretical public opinion threshold that, if reached, will force governments and large corporations to take drastic climate action.
The only issue is that this social tipping point must be reached well before the climate tipping points are reached, or else it will be too little, too late.
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