Heat records: the warmer starting point

0.75°C per decade since the mid-1990s is the key number: Copernicus/ECMWF says that is how fast the Arctic is warming in the European State of the Climate 2025 report eu-space.europa.eu, and that hotter baseline is why recent temperature records are being broken by margins that look abnormal in daily weather. WMO says Europe just saw record heatwaves from the Mediterranean to the Arctic wmo.int, while climatologist Christophe Cassou described the late-May episode as above 35°C, about 10 days early, about 10 days long, 10 to 15°C above seasonal norms, and breaking prior records by 2 or 3°C across Western Europe including the UK and Ireland lemonde.fr. The hit-or-miss frame is not whether records fall, but whether they fall at the margin or by 2 or 3°C: a standard hot spell clips records at the edge, but a warmer mean plus a persistent heat dome resets the distribution. If future episodes keep beating prior records by 2 or 3°C, chronic heat risk could get priced less like a shock and more like the base case.

0.75°C per decade since the mid-1990s is the key number: Copernicus/ECMWF says that is how fast the Arctic is warming in the European State of the Climate 2025 report eu-space.europa.eu, and that hotter baseline is why recent temperature records are being broken by margins that look abnormal in daily weather. WMO says Europe just saw record heatwaves from the Mediterranean to the Arctic wmo.int, while climatologist Christophe Cassou described the late-May episode as above 35°C, about 10 days early, about 10 days long, 10 to 15°C above seasonal norms, and breaking prior records by 2 or 3°C across Western Europe including the UK and Ireland lemonde.fr. The hit-or-miss frame is not whether records fall, but whether they fall at the margin or by 2 or 3°C: a standard hot spell clips records at the edge, but a warmer mean plus a persistent heat dome resets the distribution, which is why power, water, and insurance stress can show up alongside the weather tape. If future episodes keep beating prior records by 2 or 3°C, chronic heat risk could get priced less like a shock and more like the base case.