The many meanings of no net loss in environmental policy

© 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2018 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. 1School of Earth and Environmental Sciences, The University of Queensland, Brisbane, Queensland, Australia. 2deVilliers Brownlie Associates, Cape Town, South Africa. 3Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Canterbury, UK. 4Department of Food and Resource Economics & Centre for Macroecology, Evolution and Climate, University of Copenhagen, Copenhagen, Denmark. 5Forest Trends Association, Washington, DC, USA. 6Biotope, Mèze, France. 7Wildlife Conservation Society, Global Conservation Program, New York, NY, USA. 8RMIT University, Melbourne, VIC, Australia. *e-mail: [email protected] As humanity struggles and fails to stay within a safe operating space1,2, an increasingly influential principle in environmental management and policy is that of NNL (of biodiversity, carbon stocks, water quality and so on), along with a family of related terms and concepts, such as net positive impact, zero net deforestation and net gain. The reference to net outcomes implies an assumption that natural resources, environmental quality or biodiversity will continue to be lost due to economic development and our increasing human footprint, and that residual losses should be counterbalanced in some way by equivalent gains elsewhere. If they live up to their stated goal, NNL and net gain policies should help keep us or move us back to within planetary boundaries. No net loss and related goals have emerged for a broadening range of natural targets, from forest cover, biodiversity and fisheries to land productive capacity and carbon. Since the term NNL was first popularized during the 1988 United States presidential election campaign of George H. W. Bush3,4, such goals increasingly have become embedded within international pledges5,6, national and regional government policies7, voluntary corporate sustainability policy8 and lending requirements for major financial institutions9. For example, the European Commission is exploring policy options for a European Union-wide NNL Initiative, and countries including France, Colombia and Peru have recently introduced legislation that includes such goals10,11. Biodiversity offset policies that require NNL of biodiversity are now in place or enabled in over 80 countries7. No net loss of biodiversity or ecosystem services sounds like an appealing goal. However, the phrase is meaningless in isolation: that is, the goal is NNL in comparison to what scenario?12–14. Policy goals such as NNL must be specified relative to an alternative possible scenario: that is, the reference scenarios for the aspect of the environment targeted by the policy, over time and space. Different reference scenarios against which NNL is to be achieved make for entirely different intended outcomes for the environment. The question is, then: relative to what biophysical reference scenario is the NNL outcome sought12,14? The reference scenario against which one aims to achieve NNL is, in effect, the target outcome — and so the goal of policies that do not specify a reference scenario is unclear4. In practice, such reference scenarios are rarely articulated13,15. Thus, appropriate implementation of policies that are striving for NNL outcomes is undermined by an inability to account robustly for net outcomes, as this depends entirely on knowing the intended reference scenario15. Further, NNL and related terms are being used indiscriminately to describe what are actually two distinct policy goals: (1) an overarching goal with a broad scope, applying to all impacts (anthropogenic and natural, large and small) on the environmental target across a jurisdiction, such as a commitment to achieve NNL of biodiversity by 202016 or zero net deforestation by 201517; and (2) an impact-specific policy goal that is based on a narrower scope, such as counterbalancing losses from a particular category of development impacts using offsets18. Such impact-specific policies may be, but are not always, considered a way to help achieve overarching policy goals. Although the term NNL is used in both cases, the reference scenario against which this is to be achieved can be very different. For example, biodiversity offset policies that have a goal of NNL tend to relate only to the component of loss caused by the particular impact in question (for example, the removal of habitat to make way for an infrastructure project). Therefore, a successful NNL outcome in that instance can still mean that less biodiversity exists than before the impact, if we accept that biodiversity declines caused by factors other than the particular impact in question would have occurred13. However, overarching policy goals seem to imply a different scenario; for example, that declines in the targeted biodiversity will be halted, regardless of what is causing them. The indiscriminate and unqualified use of NNL to describe these very different (but interlinked) outcomes obscures policy debate and the capacity for evaluation. Furthermore, the opacity about reference scenarios for such goals contributes to poor practice in estimating losses and gains15 at both the level of particular impacts and across landscapes or jurisdictions. The many meanings of no net loss in environmental policy