<p>This essay argues that United States insurers have a moral duty, inherent in their underwriting function, to mitigate climate risk. This duty is bounded by two requirements. The agency requirement confines it to underwriting decisions, while the boundary requirement confines it to relationships that the underwriting of climate-related risks directly and foreseeably shapes. Within those limits, insurers should not worsen—and, where feasible, should reduce—climate-related hazard, exposure, and vulnerability. The argument proceeds through a two-level framework. Ontological–relational ethics theory explains why insurers bear other-regarding obligations that do not depend on consent, while integrative social contracts theory explains how such obligations are locally specified within plural state regulatory communities, yet remain bounded by higher-order moral limits. Read together, these theories show that state insurance regulation does not create insurers’ moral duties from nothing but gives local institutional form to duties that are already morally significant. The essay’s argument is deliberately narrow: it concerns the morally significant residual discretion insurers retain within a publicly structured regulatory field.</p>