Updated Carbon Budgets Could Reset Our Global Warming Expectations

We’re still in big trouble, but we may be overestimating our worst-case scenarios for human-caused heating

Image produced by DALL-E from iterative text prompts lost in time. Basically visualizing “what you see depends on where you look.”

I’ve argued that our climate/resource crisis is essentially an optimization problem. How do we make sure our fossil fuel binge doesn’t stop too soon, before we have built out an infrastructure to replace it, nor too late, leaving us with a planet too hot for human habitation? Recent work on the concept of carbon budgets provides new insights on when “too late” might be. It also raises the possibility that current IPCC models are overestimating how much heat our fossil fuel reserves are capable of producing.

How late is “too late” to quit fossil fuels?

One definition of “too late” might be this: If we allow warming to increase to a level that triggers an irreversible tipping point, we have waited too long to quit fossil fuels (source).

In a 2022 report that builds on tipping point research I summarized in a previous post, David McKay and an international team of climate scientists estimate the global heating thresholds at which various tipping points would become more likely than not. Here is a high-level summary of their estimates (derived from McKay et…