Missoula Statement
November 15, 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 decision-making. 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 decision-making. 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

** 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

The Precautionary Principle: "When an activity raises threats of harm
to human health or the environment precautionary measures should be
taken even if some cause-and-effect relationships are not fully
established scientifically"

Precautionary measures must:

** expand and not foreclose future conservation actions and options;

** err on the side of conservation, particularly avoiding Type II

** 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

Participants in the Missoula Meeting:
(Affiliations listed for identification purposes only)

Katherine Barrett Science and Environmental Health Network
Len Broberg University of Montana
Steve Buskirk University of Wyoming
Doug Honnold Earth Justice Legal Defense Fund
Tim Clark Yale School of Forestry
Jim Lichatowich Salmon Consultant
Lee Metzgar Population Biologist
Mary O'Brien Science and Environmental Health Network
Carolyn Raffensperger Science and Environmental Health Network
Brian Riddell Pacific Biological Station, Nanaimo, British Columbia
Len Ruggiero Rocky Mountain Research Station