Navigating uncertainty in life cycle assessment‐based approaches to biodiversity footprinting

1. The use of life cycle assessment (LCA) methods is rapidly expanding as a means ofestimating the biodiversity impacts of organisations across complex value chains.However, these methods have limitations and substantial uncertainties, which arerarely communicated in the results of LCAs.

2. Drawing upon the ecological and LCA literature on uncertainty and two workedexamples of biodiversity footprinting, we outline where different types of uncer-tainty occur across multiple stages in LCA, from input data to the choice of bio-diversity metric. Some uncertainties are epistemic, incorporating structural (e.g.the types of pressures included in models), parametric (e.g. uncertainty aroundcharacterisation factors and information gaps) and measurement uncertainty,as well as natural variability, and stochasticity. Other uncertainties are linguistic(e.g. ambiguity around definitions of biodiversity) and decision-based (e.g. choicesmade when matching company data to inventory categories).

3. Based on this review, we provide suggestions for (i) understanding, reducing andnavigating uncertainties in biodiversity footprinting and (ii) ensuring the robustand appropriate use of LCA techniques as part of broader organisational biodi-versity strategies.

4. Understanding the risks posed by these uncertainties, weighing them againstthe costs of inappropriate action or inaction and ensuring decisions are robustto these uncertainties is vital for designing effective biodiversity strategies. Byappreciating and navigating uncertainties, opportunities exist to utilise LCAs for high-level risk screening to prioritise action and highlight areas where focused ef-fort and more granular data are needed to track progress towards abating impactsyear-on-year and identify low-risk actions. However, we recommend biodiversitystrategies should not be based solely on absolute LCA impact results. Instead,LCAs should be used alongside other approaches to guide location-specific androbust action to deliver a nature-positive future.