Missoula Statement
Conservation Decisions in the Face of Uncertainty
November 2000
The conservation of ecosystems and species, a daunting task for humans, has been thwarted in part by insufficient and inappropriate use of science, particularly in the way that scientific uncertainty is reported and incorporated into decisionmaking. Ecological systems are complex, and our understanding of them will always include scientific uncertainty. However, we assert that such uncertainty must not be used to avoid responsible ecological decisionmaking. Failing to act today to conserve ecosystems and prevent species extinctions will have significant social and ecological costs tomorrow.
We believe decisions that adequately account for scientific uncertainty must:
- be made in an open and accountable process that includes sharing with all participants information used in making a decision;
- be based on disclosed standards for justifying conclusions; and
- include full disclosure of value judgements, and assumptions that underlie the interpretation of data and information.
Herein, we propose standards for disclosing uncertainty (making uncertainty explicit), reducing uncertainty, and managing in the face of uncertainty.
Disclosing Uncertainty The levels and kinds of uncertainty relevant to a decision should be fully and clearly identified and described in ways that are understandable to informed participants.
According to sound scientific practice, the description of uncertainty should include: sample sizes, duration and geographic extent of studies, and estimates of precision associated with point estimates; the limitations and dangers of extrapolating results to other geographical areas, time periods; and assumptions used to deal with uncertainty in the analysis and modeling.
All data that are used to calculate point estimates and confidence intervals and are used in other ways to arrive at a decision should be disclosed. Those data should also be made available to all participants in a decision and, open debate and discussion of alternative interpretations encouraged as a further means of ensuring that all uncertainties are identified.
Because assumptions are also sources of uncertainty, the likely social, economic and biological consequences of their being invalid should be disclosed.
Reducing Uncertainty Both the scientific uncertainties (knowledge gaps and precision of existing data) and management uncertainties (consequences of alternative actions) should be minimized. In order to minimize key uncertainties:
- research questions should be policy-informed and policy-relevant;
- data gaps should be identified through consideration of the concerns of all participants in the relevant management process;
- funding for research to reduce uncertainties and to monitor management and activities should be available and acknowledged as an inherent cost of activities and management; and
- publication should include communication to all relevant audiences, not just peer-reviewed scientific journals.
Managing in the Face of Uncertainty Decisions must be made despite uncertainty. In such cases, decision makers should use the precautionary principle to discharge their duties.
- expand and not foreclose future conservation actions and options;
- err on the side of conservation, particularly avoiding Type II errors;
- avoid irreversible consequences; and
- shift the burden of proof to those who advocate a potentially harmful action .
A precautionary approach to conservation problems for which there is limited scientific information should entail the review of all relevant scientific information and its interpretation in the context of ecological theory, making specific the link between data, theory and interpretation. This process produces qualified insights, which should clarify irreducible uncertainties in the scientific information.