Climate tipping points may be closer and more interconnected than IPCC median estimates

The IPCC reports present probabilistic ranges for climate outcomes, and the median projections are alarming enough. But I want to talk about tipping points — nonlinear thresholds in the Earth system where a small additional push triggers a large, self-sustaining change. These are the places where the smooth probabilistic framing breaks down.

The list of proposed tipping elements includes West Antarctic Ice Sheet collapse, Greenland ice sheet loss, Amazon dieback, Atlantic Meridional Overturning Circulation slowdown, permafrost carbon release, and several others. What's emerged in the last decade of research is that many of these are not independent — they're coupled. Triggering one can lower the threshold for others.

Armstrong McKay et al. (2022) compiled evidence suggesting that several major tipping points may be crossed at 1.5°C — a temperature we're now likely to exceed within this decade. That paper has been contested, and the uncertainties are genuinely large. But the structure of the argument is important: the risk function for climate damage is not smooth or symmetric. Low-probability, high-impact, irreversible outcomes deserve more decision-theoretic weight than their probability alone suggests.

For independent environmental science researchers, the publicly available climate model output and paleoclimate proxy data are extensive. What tipping dynamics do you think are most underweighted in public discourse?