Examples of global and regional tipping points FIGURE 2.5 Source McKay, et. al., 2022; OECD, 2022; Lenton, et. al., 2023. Greenland ice sheet Collapse Boreal permafrost Collapse Boreal forest Southern dieback Boreal forest Northern expansion Amazon rainforest Dieback Mountain glaciers Loss Atlantic Meridional Overturning Circulation(AMOC) Collapse Sahel/West Africanmonsoon Greening Low-latitudecoral reefs Die-off West Antarcticice sheet Collapse East Antarcticice sheet Collapse East Antarcticsubglacial basins Collapse Labrador sea/subpolar gyre Collapse Boreal permafrost Abrupt thaw Global warming thresholds 1.5°C >1.5-2°C >2-4°C >4°CCategory Cryosphere entities Circulation patterns Biosphere components taken today, estimates relating to climate tipping points may be conservative or even optimistic.11 Most climate models, whether public, private or academic, do not adequately capture non-linear impacts. For example, the transition of the Amazon into savannah will likely be caused by a combination of climate and ecological impacts, possibly transitioning well before 3°C of warming (Figure 2.5), due to land-use changes and deforestation. 12 Most models also fail to capture the interconnectedness of these systems: how could cascading effects from the passing of one tipping point lower the critical threshold for others? For example, melting of the Greenland Ice Sheet could lead to an influx of fresh water, destabilizing the Atlantic Meridional Overturning Circulation (AMOC) and creating conditions that melt the West Antarctic Ice Sheet faster. 13 Early warning signs suggest that several systems, including the Greenland Ice Sheet, AMOC and Amazon rainforest, are losing resilience, 14 and it is possible that some critical thresholds have already been crossed. 15 Indeed, not all tipping points will be observed. Some will manifest as distinct changes, such as an ocean heatwave that precipitates the collapse of coral reefs. The “edge” of these thresholds can be sharp – for example, the point at which the Greenland Ice Sheet reflects less heat than it absorbs. But not all tipping points will be visible at the current level of modelling and monitoring. The comparatively slow velocity of most critical changes to Earth systems – time between the tipping point and when impacts are fully felt – means that most will be silent, with impacts gradually building over the longer-term. As such, climate tipping points are risks that are well-known but not necessarily well-understood. GRPS results indicate that the impacts of climate change are well-recognized by global decision-makers. However, if critical changes to Earth systems are seen as longer-term risks – with likelihoods or impacts underestimated, or simply dismissed as too uncertain – intervention may come too late to prevent cascading planetary change, hindering our ability to fully adapt to related impacts. Limits to climate adaptation Over the next 10 years, many economies could remain largely unprepared for these non-linear impacts of climate change. This is not the first time that abrupt changes to our planetary system have Global Risks Report 2024 43

The Global Risks Report 2024