If global climate policies do not change, Earth faces an average 62% probability of triggering irreversible climate tipping points – critical points for the Planet’s climate system – by the end of this century.
This alarming forecast comes from a recent study published in Earth System Dynamics. Researchers from the University of Exeter and the University of Hamburg assessed the tipping point risks across 16 systems under five different global socio-economic pathways (SSPs), reflecting future emissions and transition scenarios.
What is a climate tipping point?
In climate science, a tipping point is a threshold beyond which a small rise in global temperature can trigger profound, rapid, and often irreversible changes in Earth’s systems.
These include, for example, the collapse of ice sheets, degradation of the Amazon rainforest, or mass coral reef die-offs.
Once activated, these processes can become self-sustaining, causing cascading effects that are hard to control – and hard to predict, as their development is non-linear.
How likely are we to trigger tipping points?
In the SSP2-4.5 scenario – the one most aligned with current global warming trajectories (about +2.8 °C by 2100) – the probabilities are alarming. According to the study:
- there is an average 62% chance of triggering at least one tipping point among the 16 analyzed;
- 9 out of 16 tipping points have more than a 50% chance of being activated.
In higher-emissions scenarios (SSP3-7.0, SSP5-8.5), the probability climbs to 95%. Only the most ambitious pathways (SSP1-2.6 and SSP1-1.9) can be considered relatively “safe,” bringing the risk down to 37% and 27%, respectively – though the risk remains significant.
The study also calculated the potential additional warming caused by releasing greenhouse gases from certain Earth system components that hold large carbon stores, known as “carbon tipping elements” (TEs). Researchers focused on three key systems:
- large-scale loss of the Amazon rainforest;
- rapid thawing of permafrost;
- systemic collapse of permafrost driven by internal feedback loops.
In the SSP2-4.5 scenario, these elements could add up to 0.91 °C of extra warming by 2500, with the peak impact around 2100.
The table below summarizes the probability of triggering tipping points without and with the added effect of carbon tipping elements:
| SSP Scenario | Average tipping point risk | + Carbon TEs effect |
|---|---|---|
| SSP1-1.9 | 26% | 27% |
| SSP1-2.6 | 37% | 39% |
| SSP2-4.5 | 62% | 67% |
| SSP3-7.0 | 91% | 92% |
| SSP5-8.5 | 95% | 96% |
Emissions scenarios and tipping point probabilities
The study also examined the likelihood of crossing each tipping point under different scenarios. In the SSP2-4.5 pathway, the following probabilities were observed:
- 98% probability of widespread permafrost degradation;
- 93% probability of Greenland ice sheet collapse;
- 96% probability of West Antarctic ice sheet collapse;
- 91% probability of tropical coral reef die-offs.
Other tipping points, like the collapse of the Atlantic Meridional Overturning Circulation (AMOC) or destabilization of the East Antarctic ice sheet, remain below 50%, but still pose non-negligible risks.