Scientists assessed the risk of “tipping” in 16 different parts of the Earth system — ranging from the collapse of major ice sheets to the dieback of tropical coral reefs and vast forests.

Based on current policies and the resulting global warming, their most conservative estimate is a 62% risk of triggering these tipping points on average.

However, more sustainable future pathways — with lower greenhouse gas emissions — significantly reduce the risk of tipping points.

The study, by the universities of Exeter and Hamburg, also found that carbon released by certain tipping points (Amazon rainforest dieback and permafrost thaw) is unlikely to cause enough warming to trigger other tipping points.

“The good news from our study is that the power to prevent climate tipping points is still in our hands,” said lead author Jakob Deutloff.

“By moving towards a more sustainable future with lower emissions, the risk of triggering these tipping points is significantly reduced.

“And it appears that breaching tipping points within the Amazon and the permafrost region should not necessarily trigger others.”

A “tipping point” occurs when a small change tips a system into a new state, causing significant and long-term transformation.

The study assessed tipping point probabilities in five different scenarios, known as shared socioeconomic pathways (SSPs). Professor Tim Lenton, from Exeter’s Global Systems Institute, said: “Climate tipping points could have devastating consequences for humanity.

“It is clear that we are currently on a dangerous trajectory — with tipping points likely to be triggered unless we change course rapidly.

“We need urgent global action — including the triggering of ‘positive tipping points’ in our societies and economies — to reach a safe and sustainable future.”

During the writing phase, Jakob Deutloff was funded by the German Research Foundation. Professor Lenton’s work was supported by the Bezos Earth Fund.

Located in the southern Andes between Chile and Argentina, Patagonia hosts the largest and wettest glaciated region in the Southern Hemisphere outside Antarctica. “The Southern Andes act as a natural barrier, blocking moisture-laden westerly winds from the Pacific Ocean,” explains Brice Noël, climatologist at the University of Liège. “As a result, glaciers locally receive over fifteen metres of snowfall annually, particularly on the western flank of the Andes.”

While snow accumulation at higher elevations contributes to glacier growth, rapid melting occurs at lower altitudes. “Glaciers can extend down to sea level, where warmer air triggers substantial summer melt. This meltwater eventually runs off into the ocean, leading to sea-level rise.” Scientists estimate that since the 1940s, Patagonian glaciers have lost over a quarter of their total ice volume, raising global sea level by 3.7 mm.

High-resolution climate model

The research team from Liège, Leuven, and Delft estimated the surface mass balance of Patagonian glaciers since 1940 — that is, the difference between winter snowfall and meltwater runoff in summer. “We used MAR, our regional climate model developed at the University of Liège,” adds Xavier Fettweis, climatologist at ULiège. MAR is a polar climate model that simulates snow and ice processes on a five-kilometre spatial grid, which is too coarse to represent the small-scale Patagonian glaciers. “High spatial resolution is essential to study the glacier surface mass balance in Patagonia, so we spatially refined our model to a 500-metre grid,” notes Brice Noël. Lower-resolution models fail to accurately capture narrow glacier tongues* that melt rapidly or estimate realistic precipitation over the rugged Andes. “Our high-resolution model closely aligns with in situ and satellite mass loss observations,” confirms Bert Wouters from Delft University of Technology.

What drives glacier mass loss?

Sustained mass loss since 1940 is attributed to a long-term increase in meltwater runoff to the ocean, a consequence of atmospheric warming in Patagonia. “We identify increased surface runoff as the primary driver of glacier mass loss, as snowfall has remained steady since the 1940s,” explains Brice Noël. Surface runoff intensifies when firn — the porous, perennial snow layer covering the upper glacier zones — melts away, exposing the underlying bare ice. “Bare ice is darker than the surrounding firn, thus absorbing more solar energy in turn enhancing melt and runoff,” explains Stef Lhermitte of KU Leuven.

Poleward shift of subtropical highs

Besides the effect of global warming, researchers attribute the fast increase in Patagonian temperatures to a large-scale atmospheric shift, whereby subtropical high-pressure systems migrate poleward. This shift, observed over the past forty years, channels more warm air into Patagonia, thereby amplifying mass loss. Ocean-atmosphere interactions underpinning this circulation change are driven by global warming and are likely to persist in the future. “Complete melting of Patagonian glaciers could raise global sea-level by an extra centimetre,” warns Brice Noël. “Their disappearance would endanger South American communities reliant on summer meltwater supply.” At the current rate of mass loss, scientists project that Patagonian glaciers could vanish within the next 250 years.

* A glacier tongue refers to the downstream extension of a glacier, resembling an icy “arm” descending into a valley or flatter terrain.

Iridium is known for its OER performance but is both scarce and expensive. Efficient use of Ir while maintaining stability is a major challenge for scaling up electrolyzer technologies. This study proposes a solution through a material that maximizes atomic-level efficiency.

The catalyst features a mesoporous spinel structure that allows for high Ir loading (13.8 wt%) without forming large Ir clusters. This configuration enables the formation of Co-Ir bridge sites, which show high intrinsic activity under acidic OER conditions.

Computational analysis indicates that under reaction conditions, oxygen intermediates (O*) fully cover Co3O4 surfaces, which usually passivates Co sites. However, Ir doping reactivates these sites, while simultaneously enhancing the structural integrity of the catalyst.

Leaching of both Ir and Co during reaction was significantly reduced. Compared to conventional Ir/Co3O4 catalysts, Ir and Co loss was lowered to approximately one-fourth and one-fifth, respectively. The catalyst also maintained performance for over 100 hours with an overpotential (η₁₀) of just 248 mV.

“The mesoporous architecture plays a crucial role,” explains Professor Hao Li, who led the study. “It provides space for single-atom Ir loading and helps create a stable environment for catalytic activity.”

The research combines experimental data with computational modeling, and key findings are available through the Digital Catalysis Platform (www.digcat.org), a resource developed by the Hao Li Lab to support catalyst discovery.

This work was supported by the Tohoku University Support Program. Future research will focus on tuning the doping level, scaling up the synthesis process, and exploring integration into commercial electrolyzer systems.