If economic activity is adapted to the old climate, additional warming generally pushes temperatures, water availability and extremes further from that adapted range. With convex aggregate damages, marginal annual damage per degree D′ therefore tends to rise as the world warms. This is an argued expectation under the stated adaptation baseline, not atheorem: adaptation, wealth changes, regional benefits and thresholds alter both the level and curvature of damages. A constant D′ in the preceding integration is a simplifying local approximation, and may understate later losses when convexity dominates.
