Ancestral irrigation and collective climate action

This study examines the long-term legacy of ancestral irrigation for contemporary climate change policies. Using geographic suitability for irrigated agriculture as a plausibly exogenous source of variation in historical irrigation adoption, we find that societies whose ancestors jointly practiced irrigated agriculture during the pre-industrial era tend to adopt less effective climate change policies today. Additional evidence suggests that pro-climate political responses to the growing salience of climate action, driven by exposure to severe natural disasters, are significantly weaker in societies historically dependent on irrigated agriculture. We propose and document empirically that ancestral irrigation, marked by intensive neighborhood-based cooperation and interdependence, contributed to the early formation of tight kinship networks. These networks likely constrained impersonal cooperation across kin boundaries, weakening collective pro-climate action. • This study examines a potential historical origin of variation in cooperative norms relevant for climate change mitigation. • Societies whose ancestors jointly practiced irrigated agriculture during the pre-industrial era tend to adopt less effective climate change policies today. • Pro-climate political responses to the growing salience of climate action are significantly weaker in societies historically dependent on irrigated agriculture. • Ancestral irrigation, marked by intensive neighborhood-based cooperation and interdependence, contributed to the early formation of tight kinship networks. • Ancestral kinship tightness likely constrained impersonal cooperation across kin boundaries, weakening collective pro-climate action.