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GLOBAL TIPPING POINTS REPORT 2025 - Summary

GLOBAL TIPPING POINTS REPORT - 2025

There is rising concern that several parts of the Earth system may abruptly transition to alternative stable states in response to anthropogenic climate and land-use change. Key candidates of such tipping elements include the Greenland Ice Sheet, the Atlantic Meridional Overturning Circulation, the South American monsoon system and the Amazon rainforest. Owing to the complex dynamics and feedbacks between them via oceanic and atmospheric coupling, the levels of anthropogenic forcing at which transitions to alternative states can be expected remain uncertain. Here we demonstrate how such interactions can generate spurious signals and potentially mask genuine signs of destabilization. We further review and present observation-based evidence that the stability of these four tipping elements has declined in recent decades, suggesting that they have moved towards their critical thresholds, which may be crossed within the range of unmitigated anthropogenic warming. Our results call for better monitoring of these ti

We investigate the probabilities of triggering climate tipping points under five Shared Socioeconomic Pathways (SSPs) and how they are altered by including the additional carbon emissions that could arise from tipping points within the Earth's carbon cycle. The crossing of a climate tipping point at a threshold level of global mean surface temperature (threshold temperature) would commit the affected subsystem of the Earth to abrupt and largely irreversible changes with negative impacts on human well-being. However, it remains unclear which tipping points would be triggered under the different SSPs due to uncertainties in the climate sensitivity to anthropogenic greenhouse gas emissions, the threshold temperatures and timescales of climate tipping points, and the response of tipping points within the Earth's carbon cycle to global warming. We include those uncertainties in our analysis to derive probabilities of triggering for 16 previously identified climate tipping points within the Earth system.

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The Atlantic Meridional Overturning Circulation (AMOC), a major ocean current system transporting warm surface waters toward the northern Atlantic, has been suggested to exhibit two distinct modes of operation. A collapse from the currently attained strong to the weak mode would have severe impacts on the global climate system and further multi-stable Earth system components. Observations and recently suggested fingerprints of AMOC variability indicate a gradual weakening during the last decades, but estimates of the critical transition point remain uncertain.

La marche persistante d’un climat en réchauffement se manifeste par une multitude de changements continus et progressifs. Les niveaux de CO2 dans l’atmosphère. La teneur en chaleur des océans. L’élévation du niveau de la mer à l’échelle mondiale. Chacune s’élève d’année en année, alimentée par les émissions de gaz à effet de serre d’origine humaine. Et si les records climatiques sont régulièrement battus, l’impact cumulatif de ces changements pourrait également entraîner des changements radicaux et irréversibles dans des parties fondamentales du système terrestre.

Au-delà de la longue tendance historique exponentielle, qui s'est même accélérée depuis que nous sommes parfaitement au courant du problème, voici 12 événements ou tendances politiques, sociales, énergétiques et climatiques plus récentes qui semblent encore davantage réduire nos chances de gagner la bataille du CO2 :

Nous sommes en train de changer d’époque. Certains parlent d’anthropocène, d’autres, non moins scientifiques, évoquent de grande probabilités d’effondrement civilisationnel. Ce qui s’annonce est aussi impensable pour le cerveau humain que ne pouvaient l’être l’écriture, l’agriculture à venir ou l’extinction passée des dinosaures pour un cerveau de grand singe... Énormité des constats et des déséquilibres planétaires ; pourtant, tout au quotidien semble suivre petit bonhomme de chemin. Cette étude sera consacrée à explorer, sous divers angles, la question suivante : pourquoi les gens ne changent-ils pas ?

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