A new model of Earth’s climate system suggests that if global temperatures pass the Paris Agreement’s 1.5 °C limit, it could set off a chain of irreversible tipping points. German researchers say that on the current warming path, the chance of crossing at least one of four major tipping points could climb as high as 45 percent by 2300. What does that mean for humanity? Last year, Earth’s temperature rose 1 °C above pre-industrial levels for the first time, putting the planet alarmingly close to 1.5 °C. Some experts say the world will either hit that target in the coming years or fail to do so; others argue humanity crossed the line long ago, according to Science Alert.
In a recent study, climatologists Tessa Möller and Anika Ernst Hegner of the University of Potsdam examined four potential tipping points—critical thresholds that, once crossed, could trigger rapid and severe changes across the climate system. The four they looked at are the collapse of the Atlantic Ocean’s major current system, the dieback of the Amazon rainforest, the Greenland ice sheet, and the West Antarctic ice sheet. Experts have warned the Atlantic current system could fail as early as 2050, and the Greenland ice sheet may already be very close to its tipping point. Biospheric systems like the Amazon could also flip and drastically alter Earth’s climate; some scientists believe tropical forests are already releasing more carbon than they absorb, which adds to global warming.
The research team defined the probability of exceeding any one of these thresholds as a “tipping risk.” Using a new conceptual model, Möller and Hegner assessed tipping risks over three time frames: short term (to 2100), medium term (to 2300), and long term (over 50,000 years). Their simulations suggest that at the current rate of warming, tipping risk could reach 45 percent by 2300, and over the very long term it could rise to about 76 percent. While those long-range numbers look far off, today’s emissions and policies will determine which climate trajectory the planet follows.
The study underscores the importance of meeting the Paris Agreement’s limits. If global temperatures exceed 1.5 °C, even briefly, there may be no turning back. The authors say achieving net-zero greenhouse gas emissions by 2100 is crucial to minimizing long-term tipping risks. In short, the stability of Earth’s climate system is hanging in the balance. The results were published in the journal Nature Communications.
