What did the Lancet commission actually say? The Lancet Commission on 21st Century Global Threats to Health, unveiled on Oct 11 at the World Health Summit in Berlin, assessed 17 threats to human health through 2100, measured in years of healthy life lost. Two — nuclear conflict and the malicious use of artificial intelligence — were judged to carry a “non-zero” risk of human extinction this century. Climate change sat in a second tier of “major catastrophic threats”, alongside air pollution and high blood pressure. The largest burdens in the ranking were obesity (23.1 billion healthy years), low educational attainment (16.1 billion) and income inequality (13.8 billion); malicious AI counted 10.4 billion and nuclear conflict 9.35 billion. Keeping warming to about 1.8°C rather than 4.4°C would avert 1.89 billion lost healthy years, the commission estimated.
So why are health experts objecting now? In a row reported by The Observer on Oct 31, leading health experts accused the report of downplaying climate change. Dr Vanessa Kerry, the World Health Organization’s special envoy for health resilience, said it “did not make sense to separate climate change as its own category of risk”. Her argument is that climate change is not one threat among many but the amplifier of most of the others: “The way most of us experience climate change is not in degrees of temperature. It is our health. The air we breathe, the extreme summer heat, the floods and disease outbreaks.” A second expert, unnamed in the report, put it more sharply: the assessment “presents climate change as if it’s a problem for the next century, not this one”.
What specifically rankled? A graphic accompanying the report indicates climate change could cause less harm than smoking, obesity or alcohol use. The commission says the graphic is “not a ranking of policy priority and should not be read as one” — but Kerry’s warning is that policymakers will read it exactly that way. The Lancet is, she noted, “deeply respected” by policymakers, and “the way threats are quantified and presented here could encourage decision makers to prioritise one over another” — and therefore to fund one over another. The commission’s method multiplies harm by probability, so a small chance of a huge catastrophe counts the same as a large chance of a smaller one; its extinction estimates for AI and nuclear war rest on expert judgement and “superforecasters” rather than historical data, with uncertainty ranges stretching from zero to tens of billions of healthy years.
Is there a politics behind the row? The critics think so, and they point to attention as a finite resource. The Observer’s report notes broader concern among climate scientists that AI is absorbing politicians’ time and energy at the expense of cutting greenhouse-gas emissions. It also notes that the commission is co-chaired by Christopher Murray, director of the University of Washington’s Institute for Health Metrics and Evaluation, which recently received a $540.2 million grant from the Gates Foundation — and that Bill Gates last year criticised a “doomsday outlook” on climate change for focusing on emissions goals rather than measures “to improve life in a warming world”. None of that invalidates the commission’s arithmetic. But it explains why its framing lands, for its critics, as a choice about what counts as urgent.
Where does that leave the argument? Both sides agree on the underlying fact that matters most: the threats interact. A hotter world means more heat deaths — heat killed a record 710,000 people in 2023 alone — more disease, worse air, weaker harvests, and more pressure on every health system the commission studied. The commission’s own message was that humanity still has agency to act. The critics’ reply is that agency needs a correct map of the danger, and a map that files climate change under “major” while AI and nuclear war get “extinction” will send the money and the ministers to the wrong rooms first.
Related coverage on this site: heat killed a record 710,000 people in 2023, and our explainer on antimicrobial resistance, another threat on the commission’s list.
