At the Bonn climate talks in Germany on June 8-18, alongside the usual laundry list of contested themes like climate finance, tipping points became an unexpected source of debate and controversy.
According to the Earth Negotiations Bulletin, India urged care and clarity in using terms like “tipping points”, which it said would present challenges around defining the idea and cautioned against mis-communicating or oversimplifying the science.
However, the European Union muddied the waters by raising concerns about “coordinated misinformation” and “obstruction”.
Complexities, uncertainties
A climate tipping point is a threshold in the earth’s climate system beyond which a part of it jumps into a new state. Once such a tipping point has been crossed, changes can happen faster or harder to reverse on human timescales, even if the original cause of the change is removed.
For example, say warming in the Arctic melts enough sea ice to expose large areas of dark ocean. These waters could absorb more heat, causing more warming and even more melting. With enough heat, this cycle may be able to continue on its own, rendering recovery very difficult.
However, it is difficult to project tipping points in the climate because of complexities in the climate system and uncertainties in the input data. Climate communicators also struggle with this concept: some see it as a catalyst for urgent action while others have argued that its inherent uncertainties undermine its value for policymaking.
In fact, climate-related drivers of directly experienced disasters, such as extreme rainfall or heatwaves, are sometimes seen as more effective for raising public awareness of climate change and the need for climate action than the relatively abstract concept of climate tipping points.
However, the risks that tipping points carry are significantly larger than routine climate-induced disasters, and thus raise larger questions about how people can adapt to the effects of a breached tipping point.
Multiple thresholds
Tipping points have non-linear behaviour. This means they don’t increase at the same pace or intensity at which greenhouse gases accumulate in the environment. Instead, even small increases in temperature can trigger large, self-amplifying feedback loops.
Aside from warming in Arctic, potential climate tipping points include a ‘dieback’ of the Amazon rainforest (i.e. the risk of the forest reverting to being a savannah), the collapse of an ocean current called the Atlantic meridional overturning circulation (AMOC), the mass-bleaching of coral reefs, changes in the monsoons over India and West Africa, and the disintegration of the Greenland ice sheet.
While human societies will be better off not threatening any of the climate tipping points, there are also positive social tipping points in the climate space — such as the adoption of renewable energy. Once these technologies win a critical adoption level, some experts have argued, they will be on track to large-scale adoption.
Contesting tipping points
That said, many experts have also said tipping points raise more questions than answers. Scientists also still struggle to project when the AMOC will collapse or when the Amazon rainforest will transition into a savannah ecosystem.
One reason is that scientists have to work with projected emissions and temperature ranges in future and, based on that, they have returned with indications that certain climate systems will change slowly rather than suddenly to new states.
For example, one Science Advances paper in April noted that AMOC could slow down by 51%, rather than altogether collapse, by 2100 in a medium-emissions scenario. This conclusion also depends on the model context because it is not a direct forecast: the paper only aimed to identify which model projections were more credible than others. In other words, uncertainties are implicit in the data and cannot be removed using more data alone.
In fact, research suggests that scientists may be able to identify fixed tipping points clearly only in post facto analysis from a historical lens. Meaning, in hindsight.
And in the case of complex ecosystems like the Amazon rainforest, whose fate is closely tied to millions of tribal and urban community members and numerous artisanal enterprises, a projection of tipping points based only on changes in the climate would miss influences due to, say, cattle-ranching and human deforestation — and underestimate the implications of a change to a savannah.
That said, some scientists have also contested whether tipping points will be abrupt. For example, ice sheets deplete over thousands of years — which is far from abrupt for human observers.
A faux threshold
There is a popular notion that the earth’s surface warming beyond 1.5 C is a tipping point. The confusion persists even among participants in climate negotiations, research published in 2019 found.
However, negotiators adopted this number as well as 2 C at the COP21 climate talks in 2015 as a political target based on scientific evidence that warming beyond 1 C, 1.5 C or 2C will increasingly disrupt the climate. The temperature goals are not tipping points in and of themselves.
At the Bonn climate talks, when India urged caution on how the term ‘tipping point’ is defined and used, the European Union said that amounted to “misinformation”.
Specifically, India argued that the term ‘tipping point’ entails “definitional challenges”. This much has been acknowledged in independent scientific research and in state-led efforts. For instance, the U.K.’s national meteorological office is working on a project titled ‘An Up-HILL Battle: Building consensus on terminology for high impact climate events and tipping point risks’. According to a project document: “Unclear and inconsistent terminology for high impact climate phenomena, including concepts such as tipping points, irreversibility, ‘collapse’ and ‘shutdown’, presents a substantial barrier to clear understanding of Earth system risks.”
Way from here
Many scientists and science communicators agree that clearly communicating scientific uncertainty is a good thing because it builds trust. Both false alarm and a false sense of hope can affect credibility when, say, a projection or a forecast doesn’t come to pass. The risk — rather than the certainty — implicit in tipping points is also significant enough to warrant climate action.
In one 2025 article in Nature Climate Change, researchers from Canada, Switzerland, the U.K., and the U.S. criticised the ‘tipping points’ framework for “oversimplifying the diverse dynamics of complex natural and human systems and for conveying urgency without fostering a meaningful basis for climate action.”
They also called for more clarity, especially on the degree of abruptness, the reversibility of changes, and feedback-driven self-amplification.
“Climate change is already causing demonstrable and obvious harm around the world,” the researchers wrote. In tipping point discourse, on the other hand, “there is no specific increment of temperature increase that science can identify as the boundary between our current, already-dangerous climate and a future catastrophic climate, and no justification for doomism and paralysis while the world continues to warm.”
Rishika Pardikar is a freelance journalist.
