In the 1960s, Soviet climatologist and mathematician Mikhail Budyko set out to explore the potential future of a planet threatened by nuclear apocalypse. His investigation was motivated by a pressing question:: if the global climate changed dramatically and catastrophically in the past, could humans change it today? Inspired by the idea that the ancient Earth might once have been a ball of ice, Budyko developed a mathematical model. He proposed that if sea ice expanded beyond a critical latitude, its reflective surface would reflect more sunlight back into space, triggering a runaway feedback loop: the planet would continue to cool until ice covered everything.

Experts feared that if the US and the Soviet Union detonated their nuclear arsenals and blocked out the sun, they would destroy life on the planet. Although the missiles were not launched, it turned out that nuclear weapons were not necessary for humanity to change the climate.

Mathematicians have since uncovered the potential for sudden and radical shifts in Earth's climate, known as turning points (tipping points). These points are wildly dramatic, but also wildly uncertain. They represent the worst-case scenarios of climate models: a reorganization of the world as we know it, and of human civilization, into a new equilibrium state – an unimaginable and terrifying unknown.

If we exceed these thresholds, the consequences will be devastating: the loss of sea ice could cause the oceans to absorb more of the sun's heat, leading to uncontrollable ice melt and rising seas. The Amazon rainforest could turn into savanna. Coral reefs could completely fade.

The most watched potential tipping point is Atlantic Meridional Overturning Circulation (AMOC), a vast current that drives salt and heat across the Atlantic. This “conveyor belt” supplies Nordic Europe with about 1.2 petawatts of heat—about a hundred times the annual energy produced by humans. If it were disrupted by an influx of freshwater from melting Greenland ice or warmer ocean temperatures, the consequences could be catastrophic: fertile land in the British Isles and Scandinavia could freeze over, and Scotland could turn into Siberia.

In 2023, shocking research by Peter and Susanne Ditlevsen came to the fore. Testing new techniques for analyzing nonlinear systems, the Ditlevsens found that AMOC collapse could occur between 2025 and 2095, with 95 % certainty, while they expect it to happen in 2057This specific date caused their study to gain enormous public attention. It was referenced in the media and resembled a fictional movie. The day after tomorrow.

However, the mathematics of the turning points themselves is burdened with uncertainty. Climatologists cannot directly observe many states of the Earth and must make many assumptions. Maya Ben-Yami, a climate researcher, argues that the uncertainties in historical data are too large to extrapolate meaningful predictions of the future of the AMOC. For example, some of the surface temperature data that the Ditlevsens used as a “current fingerprint” comes from 19th century and were obtained using buckets thrown into the sea by whalers.

It is frustrating for people that these dramatic changes could be relevant to them, their children or grandchildren, and they constantly ask: When? Despite the uncertainty, however, Susanne Ditlevsen warns that with today's knowledge we cannot rule out a complete collapse.

Although the debate about the exact date and type of collapse sometimes seems “fruitless,” the stability of the Earth’s climate is not something that should be taken for granted. Our climate is not destined to remain hospitable forever. Whether the dire predictions come true in 2057 or later, the answer to averting disaster remains the same and is “no rocket science”: we must reduce carbon emissions. JRi