In the summer of 2026, Basel had 52 days of 30 °C or more: more than half the summer.
Every figure here comes from an official body: measured, counted or calculated by an authority, or derived by this audit from official figures. A label on each says which, next to its year and source. Estimates, projections and averages carried over from elsewhere are left out. Legal limits and targets appear only as reference values.
Overall grade: C. Good governance on paper. The official data show emissions down 6% from 2020 to 2022, a heating transition under way, record heat, air that meets most but not all Swiss limits, and chemical contamination that is still in the ground.
Grades by area
- C Climate mitigation: Emissions fell 6% from 2020 to 2022, by the canton's own calculation. Its path to net zero in 2037 needs a further cut of a quarter by 2027. Heating is changing, and the change can be counted.
- D Heat and adaptation: 2026 brought the most hot days ever measured in Basel. The city's tree canopy is back at its 2012 level.
- D Chemical legacy in soil and groundwater: 1,718 contaminated sites are registered in the two Basel cantons. At Klybeck, where a new district is planned, the canton still measures the carcinogen benzidine in the groundwater.
- C+ Air quality: In 2025 nitrogen dioxide met the Swiss annual limit at both Basel stations. Fine particles at Feldbergstrasse did not, and ozone exceeded its hourly limit for hundreds of hours.
- C+ Drinking water and rivers: Tap water stays more than a hundred times below the PFAS maxima. Groundwater and fish do not look as good.
- D+ Noise and traffic: One resident in five lives with road noise above the legal limit at night, eight years after the federal deadline for remediation.
This page draws its charts with JavaScript. The full data is in assessment.json.