A June 2026 heatwave in France caused more than 2,700 heat related deaths, according to a new analysis by Andrew Dessler and Chris Callahan. Observed temperatures outpaced climate model projections, with June highs matching what models expected for the 2070s. The authors argue this shows climate impacts are already severe, even if the worst case emissions scenario RCP8.5 is no longer considered plausible. The analysis uses a U shaped mortality temperature relationship to estimate excess deaths. It also points out that models may be underestimating extreme heat in Europe due to factors like aerosol reductions and circulation changes. This matters for anyone tracking climate risk, adaptation planning, or the real world cost of delayed decarbonization.
