This is the latest and greatest meme to scare the world of climate collapse, and it is gathering momentum and triggoring followers.  A sanity check is published at climatetippingpoints, despite being prone to CO2 Hysteria. The article is Fact-Check: have actuaries predicted that billions will die beyond 2 degrees? Excerpts below with my bolds and added images.

Roger Hallam (the co-founder of climate activist groups like Extinction Rebellion and Just Stop Oil) has widely promoted this, repeatedly stating for example that “the British insurance sector once did an analysis showing that at 3 degrees Celsius of global warming, 4 billion people could die — and at 2 degrees, 2 billion lives could be lost. But that’s not even the full truth — it’s the minimum.” Hallam has also noted that the trial of some Just Stop Oil activists (which resulted in acquittal) included the court taking “4 billion deaths at 3°C” as an “agreed fact“.

Based on this analysis, Hallam has co-founded a new campaign called ‘4 Billion Dead‘ (4BD), explicitly referencing the 3°C-based number in its name, connecting it to an outlier estimate of 3°C by 2050 (itself based on a linear extrapolation of just the last few years’ warming), and using it as the basis for planning and promoting a new civil disobedience campaign:

So where did these numbers come from then, and are they reliable?

The source is this report jointly written by authors from the Institute and Faculty of Actuaries and the University of Exeter, titled “Planetary Solvency – finding our balance with nature” (pdf).

[However, details in the Risk impact matrix give the game away–see below]

Does this confirm then that the Planetary Solvency report is predicting there’ll be 2 billion dead at 2°C or more, and over 4 billion deaths at over 3°C? It may seem like it, but the answer is actually no – the numbers in this dashboard and supporting appendix are labelled as illustrative (as flagged above both instances, including on the latter that it is “not a prediction or central scenario“).

This means these are just hypothetical numbers to show how such a dashboard would work, and not empirical predictions or projections based on some underlying analysis. This has been confirmed by speaking to one of this Planetary Solvency report’s authors, who agreed that these numbers aren’t based on a specific scientific analysis (with no associated calculations on death numbers presented in the report’s supplementary material either, unlike for GDP), rather being meant as a hypothetical illustration of a worst-case scenario to measure risk against, to be followed later with more detailed empirical analyses. Critically, the worst-case scenario here is implicitly part of a spread of many potential outcomes at 3°C, rather than 3°C itself being the worst-case scenario with these numbers the expected outcome if it is reached.

This means that even taking this report as it stands (leaving questions around the robustness of the magnitude of these death and GDP numbers to other posts), these numbers cannot be treated as predictions by actuaries (which implies an empirically-grounded expectation of the most likely future resulting from 3°C), in contrast to how they’ve been referred to in the earlier quotes, social media posts, and campaigns. Instead, they can at most be interpreted as (and for clarity should be communicated as) provisional expert ‘guesstimates‘ of a potential worst-case scenario, which was used to test-run a climate risk analysis methodology,

The UK insurance industry has not predicted mass death then, and four billion dead at 3°C is not an agreed fact but a misunderstood hypothetical worst-case scenario awaiting study. Some of the example reactions above could be down to an honest but widespread misreading, given that media outlets at the time reported these numbers like they were empirical estimates and lacked subsequent pushback (e.g. The Guardian article in January 2025), and skim-reading the report itself one might miss the “illustrative” labels.

It might be argued by some promoters that presenting this scenario as a prediction made by a respected body anyway is useful for promoting appropriately urgent action, but such misrepresentation runs the risk of fuelling scepticism or fatalism too. [You Think?]