Abstract
<title>Abstract</title> <p>Deliberate atmospheric intervention is becoming part of the climate adaptation toolkit, yet its cross-border consequences fall outside existing climate governance frameworks. Drawing on 42 transboundary corridor pairs (2000–2023), this paper provides exploratory evidence of an association between upstream atmospheric water resource manipulation (AWRM) programme intensity and downstream infrastructure economic exposure. Fixed-effects panel estimates place this association broadly in the range of 7–12% per standard deviation, amplified in hydrologically stressed corridors. A stylised game-theoretic framework illustrates why non-cooperative equilibria generate inefficient outcomes when upstream states internalise only a fraction of corridor-wide costs. These are risk signals rather than verified causal estimates. The paper frames AWRM as a problem of climate governance rather than of meteorology alone: a policy-induced, cross-border environmental externality that current adaptation and water institutions are not designed to manage. Possible governance responses include prior notification obligations, shared atmospheric monitoring, and adaptation cost-sharing mechanisms.</p>