Reviewing climate tipping point interactions and cascades under global warming

Abstract

Climate tipping elements are large-scale subsystems of the Earth that may transgress critical thresholds (tipping points) under ongoing global warming, with substantial impacts on biosphere and human societies. While recent scientific efforts have improved our knowledge on individual tipping elements, the interactions between them are less well understood. Also, the potential of individual tipping events to induce cascading tipping elsewhere, or stabilize other tipping elements is largely unknown. As a contribution to the Global Tipping Points Report (GTPR) 2023 for COP28, we mapped out the current state of the literature on interactions between climate tipping elements. We find that tipping elements in the climate system are closely interacting, meaning a substantial change in one will have consequences for subsequently connected tipping systems. A majority of interactions between climate tipping systems are destabilising. While confirmation or rejection through future research is necessary, it seems possible that interactions between climate tipping systems destabilise the Earth system in addition to climate change effects on individual tipping systems. Further, we are quickly approaching global warming thresholds where tipping system interactions become relevant, because multiple individual thresholds are being crossed. Concretely, tipping cascades can neither be ruled out on centennial to millennial timescales at global warming levels between 1.5–2.0°C, nor on shorter timescales if global warming would surpass 2.0°C. To address crucial knowledge gaps in tipping system interactions, we propose four strategies forward combining observation-based approaches, Earth system modelling expertise, computational advances, and expert knowledge.