Abstract
Biodiversity offsetting is the practice of using conservation actions, such as habitat restoration, management, or protection, to compensate for ecological losses caused by development activity, including construction projects. The typical goal of offsetting is no net loss (NNL), which means that all ecological losses are compensated for by commensurate offset gains. We focused on a conceptual and methodological exploration of net positive impact (NPI), an ambitious goal that implies commitment beyond NNL and that has recently received increasing attention from big business and environmental nongovernmental organizations. We identified 3 main ways NPI could be delivered: use of an additional NPI multiplier; use of slowly developing permanent offsets to deliver additional gains after NNL has first been reached during a shorter offset evaluation time interval; and the combination of permanent offsets with partially temporary losses. An important and novel variant of the last mechanism is the use of an alternate mitigation hierarchy so that gains from the traditional third step of the mitigation hierarchy (i.e., onsite rehabilitation) are no longer be counted toward reduced offset requirements. The outcome from these 3 factors is that for the same ecological damage, larger offsets will be required than previously, thereby improving offset success. As a corollary, we show that offsets are NNL only at 1 ephemeral point in time, before which they are net negative and after which they become either NPI or net negative impact, depending on whether permanent offsets are combined with partially temporary losses or if temporary offset gains are combined with partially permanent losses. To achieve NPI, offsets must be made permanent, and they must achieve NNL during an agreed-upon offset evaluation period. An additional NPI-multiplier and use of the modified mitigation hierarchy will deliver additional NPI gains. Achieving NPI is fully conditional on prior achievement of NNL, and NNL offsets have been frequently observed to fail due to inadequate policy requirements, poor planning, or incomplete implementation. Nevertheless, achieving NPI becomes straightforward if NNL can be credibly reached first.
Highlights
Biodiversity is almost universally in a state of decline, and the rate of ecosystem degradation, which underlies much of biodiversity loss, is accelerating rather than stabilizing (e.g., Mace et al 2018; IPBES 2019; IPCC 2019)
Despite limited implementation so far, the relatively common global policy indicates that biodiversity offsetting can have an important role to play in minimizing losses or even delivering net positive biodiversity impacts to compensate for infrastructure development and land use
What we propose is a reorganization of the mitigation hierarchy wherein its third stage becomes the last step and provides net positive impact (NPI) rather than reducing requirements of no net loss (NNL) (Fig. 2)
Summary
Biodiversity is almost universally in a state of decline, and the rate of ecosystem degradation, which underlies much of biodiversity loss, is accelerating rather than stabilizing (e.g., Mace et al 2018; IPBES 2019; IPCC 2019). Ecological losses from infrastructure development as well as from other anthropogenic land uses could potentially be curbed by a large-scale adoption of biodiversity offsetting (Rainey et al 2015; IUCN 2016a; Willemen et al 2020). Biodiversity offsetting (hereafter offsetting) is the practice of balancing ecological losses with ecological gains generated through actions, such as ecological restoration, establishment of new protected areas, or some form of habitat management (Gibbons & Lindenmayer 2007; McKenney & Kiesecker 2010; Wende et al 2018). Despite limited implementation so far, the relatively common global policy indicates that biodiversity offsetting can have an important role to play in minimizing losses or even delivering net positive biodiversity impacts to compensate for infrastructure development and land use.
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