What is ‘good evidence’ for environmental decision making? Insights from professionals working at the science-policy interface

Effective protection and management of natural ecosystems demands policies and decisions that are based on the best available evidence. However, it remains unclear how policymakers define evidence and prioritize or neglect different evidence types in environmental decisions. Here we analyze perspectives and experiences of Canadian professionals working at the science-policy interface to develop a definition of “good evidence” for environmental policy, and assess the evidence types (e.g., peer reviewed science, Indigenous knowledge, expert consultation) used most frequently to inform environmental decisions. We derived a new definition of “good evidence” from the participant responses, as follows: Good evidence for environmental policy is reliable, diverse information collected systematically through established methodologies (including Western social and natural science, Indigenous science, and place-based knowledge accumulated intergenerationally by close and continuous observation) that is credible and yields practical advice or relevant conclusions while being transparent about uncertainties. We found that a majority of environmental policymakers use peer reviewed literature mostly from the natural sciences to guide policy decisions. Evidence arising from local knowledge, Indigenous knowledge, and the social sciences tends to be neglected. However, there was a sense that perceptions of what constitutes evidence is changing and that implicit biases that prioritize some types of information over others are being questioned. Different conceptions of the salience, credibility and legitimacy of information types fundamentally shape debates around best practices for evidence-informed decision making. We suggest several routes toward a more holistic framing of environmental policy problems.