Scientific shortcomings in environmental impact statements internationally

1. Governments around the world rely on environmental impact assessment to
understand the environmental risks of proposed developments. 2. To examine
the basis for these appraisals, we examine the output of environmental
impact assessment processes in jurisdictions within seven countries,
focusing on scope (spatial and temporal), mitigation actions, and whether
impacts were identified as ‘significant’. 3. We find that the number of
impacts characterized as significant is generally low. While this finding
may indicate that environmental impact assessment is successful at
promoting environmentally sustainable development, it may also indicate
that the methods used to assess impact are biased against findings of
significance. To explore the methods used, we investigate the
environmental impact assessment process leading to significance
determination. 4. We find that environmental Impact assessment reports
could be more transparent with regards to the spatial scale they use to
assess impacts to wildlife. We also find that few reports on mining
projects consider temporal scales that are precautionary with regards to
the effects of mines on water resources. Across our sample of reports, we
find that few environmental impact assessments meaningfully consider the
different ways that cumulative impacts can interact. 5. Across countries,
we find that proposed mitigation measures are often characterized as
effective without transparent justification, and sometimes are described
in ways that render the mitigation measure proposal ambiguous. 6. Across
the reports in our sample, professional judgement is overwhelmingly the
determinant of impact significance, with little transparency around the
reasoning process involved or input by stakeholders. 7. We argue that the
credibility and accuracy of the environmental impact assessment process
could be improved by adopting more rigorous assessment methodologies and
empowering regulators to enforce their use.