Overview

• A BfG-Deltares analysis for the IKSR finds the Rhine’s average water temperature may climb 2.9–4.2 °C above the 1990–2010 baseline by 2100.
• Mid-century projections show a 1.1–1.8 °C rise, with annual days under 10 °C falling from 170 to 104 and days over 21.5 °C rising from 32 to 106.
• Southern sections from Switzerland to Karlsruhe face the steepest temperature increases, worsened by record low flows in spring 2025.
• Prolonged exceedance of critical heat thresholds will reduce dissolved oxygen and subject aquatic species to heat stress.
• Authorities are evaluating adaptation options, including shaded habitats in tributaries and floodplain restoration, to mitigate ecological damage and sustain cooling-water supplies.