[LUM#23] What if the Earth Tilted?
Since the 2000s, the theory of tipping points has gained ground in the modeling of climate and ecological change. For its proponents, taking runaway phenomena into account is essential for informing public policy decisions. We discuss this with Vasilis Dakos, an ecologist at the Institute of Evolutionary Sciences in Montpellier.
The world has likely passed its firsttipping point related to climate change. Tropical coral reefs, which are experiencing repeated bleaching events due to ocean warming, are undergoing “widespread decline,” according to the report *Global Tipping Points*, published in October 2025. The study establishes the tipping point for corals at +1.2°C above pre-industrial levels. Today, the planet has reached +1.5°C. And other systems may be on the verge of crossing this point of no return, such as the cryosphere, which has begun to melt, or the Amazon rainforest, which is undergoing savannaification.
One of the 160 scientists involved in this report, Vasilis Dakos, an ecologist at the Institute of Evolutionary Sciences in Montpellier (ISEM), emphasizes the importance of this concept for understanding the changes currently underway (“Tipping Point Detection and Early Warning in Climate, Ecological, and Human Systems”, European Geosciences Union, 2024). One of the characteristics of a tipping point is its irreversibility.“Once it is crossed, it is virtually impossible to go back, even by recreating the previous conditions,” explains the specialist. Thus, once melted, Antarctic ice will not reform, even at early20th-century temperatures.
Feedback Loops
Also at play are complex phenomena that combine and reinforce each other’s effects—“feedback loops,” explains Vasilis Dakos. The thawing of permafrost, for example, releases CO2 and methane, which amplifies the greenhouse effect—and thus global warming—which in turn leads to further thawing, and so on. Another critical case is that of the Amazon rainforest. This vast forest creates its own hydrological cycle, producing so much moisture that it generates clouds and rain. With climate change, drought will cause some of the trees to die, thereby reducing the amount of water vapor released in the region, which will increase the drought, accelerating the death of the trees… (Emerging Signs of a Decline in Forest Resilience to Climate Change, Nature, 2022) Worse still, drought fuels wildfires that release massive amounts of carbon into the atmosphere, further exacerbating global warming. This cycle will ultimately lead to the Amazon’s transformation into savanna.
Based on René Thom’s mathematical work in the 1960s (video: René Thom or catastrophe theory), the theory of tipping points in the Earth system emerged in the early 2000s. Ecologists were the first to apply this mathematical model to ecological systems. Climate scientists subsequently identified about 40 feedback loops in the Earth’s climate system, two-thirds of which exacerbate global warming, according to an international study published in *One Earth* in 2023.
"A real risk to consider"
In ecology, where systems are even more complex than in climatology, proving that a tipping point exists is no easy task.“It’s an indirect modeling approach that doesn’t allow us to pinpoint exactly where the tipping point is, but it is capable of showing the amplification of feedbacks that drive the system into a crash,” explains Vasilis Dakos. “It’s not foolproof, but it works well enough to show that there’s a real risk we need to take into account!”
To confirm their theory, proponents of the existence of tipping points have analyzed fossil data on geological timescales. “But it remains difficult to demonstrate whether and how a tipping point occurred in the past. So skepticism about the relevance of tipping points persists among some members of the scientific community ,” explains the researcher. This concept should not, however, be confused with ecological thresholds—those critical points that characterize the response of certain ecosystems under stress, which no one disputes.
"A doomsday mentality that doesn't go over well"
“Tipping points also imply a sense of doom and gloom that people don’t like, ”acknowledges Vasilis Dakos.“But despite the uncertainty, taking the risk of ignoring these phenomena can have dramatic consequences.” ” He goes on to explain that mitigation efforts are approached differently when we know we’re not dealing with a linear phenomenon but rather an acceleration that could tip everything over. Proponents of the concept are even concerned that reaching one tipping point could trigger them all, since certain interconnected systems can destabilize one another.
As evidence that the concept is gaining ground in climate science, a large-scale European project called Climtip was launched in 2024 and will contribute to the scientific literature for the next IPCC report.“In this project, our team BioDICéeis studying the impact of tipping points on biodiversity. We’re simulating scenarios in our models where the climate system tips—in my case, a shutdown of the Atlantic Ocean Circulation (AMOC) and the conversion of the Amazon into savanna—and we’re assessing the risk of extinction for more than 50,000 terrestrial species. ” This work will allow us to compare future scenarios with and without tipping points. Hopefully, this exercise will finally trigger a political tipping point in the fight against climate change.
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