Climate change creates a long-lived fiscal exposure that conventional budget accounting only partially observes. Physical hazards destroy productive assets, interrupt revenue collection, reduce potential output and increase reconstruction spending. These effects interact with sovereign risk premia and debt dynamics, while adaptation investment entails up-front expenditure whose benefits emerge over uncertain horizons. This study develops a unified macro-fiscal and legal account of the cost of inaction. It distinguishes observed economic losses, public contingent liabilities, foregone tax revenue, adaptation requirements and the welfare cost of irreversible damage; evaluates recent findings of the IMF, UNEP, EEA and European Commission; and offers an explicitly illustrative twenty-year debt simulation comparing delayed action, domestically financed adaptation and co-financed adaptation.  […]