Scientific shortcomings in environmental impact statements internationally

Governments around the world rely on environmental impact assessment (EIA) to provide rigorous analyses and an accurate appraisal of the risks and benefits of development. But how rigorous are the analyses conducted in EIAs, and how do they compare across nations? We evaluate the output from EIAs for jurisdictions in seven countries, focusing on scope (temporal and spatial), mitigation actions, and impact significance determination, which is integral for decision-making. We find that in all jurisdictions, the number of identified significant adverse impacts was consistently small (or nonexistent), regardless of context. Likely contributing to this uniformity, we find that the scopes of analyses are consistently narrower than warranted ecologically and toxicologically, many proposed mitigation measures are assumed to be effective with little to no justification,and that the professional judgement of developer-paid consultants is overwhelmingly the determinant of impact significance, with no transparent account of the reasoning processes involved. EIA can be salvaged as a rigorous, credible decision-aiding tool if rigor is enforced in assessment methodologies, regulators are empowered to enforce rigor, and pro-development conflict of interest is avoided.