Geopolitical tensions have increasingly emerged as an important determinant of environmental sustainability, yet empirical evidence on the geopolitical risk–environment nexus remains fragmented and inconclusive. This study examines the impact of geopolitical risk on CO₂ emissions in a panel of 24 countries over the period 1994-2020, with particular attention to distributional heterogeneity and the role of environmental policy stringency. Grounded in the STIRPAT framework, the analysis employs the System Generalized Method of Moments (System GMM) to address persistence and endogeneity and applies Method-of-Moments Quantile Regression (MMQR) to capture heterogeneous effects across the emissions distribution. The results indicate that higher geopolitical risk is associated with increased CO₂ emissions, supporting the escalation hypothesis. The quantile estimates reveal stronger effects at lower and middle emission quantiles and weaker effects at higher quantiles, indicating substantial distributional heterogeneity. Nonlinear estimates further suggest that the environmental consequences of geopolitical risk vary with the intensity of geopolitical stress. Environmental policy stringency consistently reduces emissions and serves as an important conditioning factor in the geopolitical risk–emissions relationship. Regime-based estimates show that geopolitical risk remains positively associated with emissions under low- and medium-stringency policy environments, whereas the relationship becomes statistically insignificant in high-stringency regimes. The findings highlight the importance of environmental governance, regulatory capacity and institutional resilience in shaping environmental outcomes under geopolitical uncertainty, with important implications for SDG 13 (Climate Action) and SDG 16 (Institutions).