Fishlake Habitat Creation. Credit: Giles Rocholl Photography

+ Properly implemented, biodiversity offsetting should provide quantifiable benefits that mitigate the ecological impact of a development.

Biodiversity offsetting is on the rise and is probably here to stay. It divides environmental practitioners, conservationists and the proponents of development projects. Yet, as a concept, I believe it is often poorly understood. Properly implemented, offsetting is far from the ‘licence to trash’ that its critics would argue. The problem is that it’s not often implemented as intended.

Offsetting is a mechanism for addressing the unavoidable residual impacts of development upon biodiversity. So, for example, a new recycling plant to be built on an area of grassland is unlikely to be able to address all of its impacts to grassland ecology on-site because of the limited space available. This may therefore trigger the need for additional compensation through offsetting, such as enhancing another poorer-quality grassland area off-site. Offsets like this should be designed to deliver quantifiable benefits (and an overall net ecological gain) as part of the drive to halt and reverse broader biodiversity declines - declines that are happening everywhere

The established principles of offsetting make it clear that it exists to address impacts only after all other mitigation options have been exhausted. That means that all measures to avoid, to reduce, to rehabilitate and restore have been applied to the project and the alternatives revisited, by the time that offsetting is considered as a last resort. Historically, the planning system has allowed minor residual adverse impacts to slip through unnoticed and unaccounted for. So offsetting now appears to offer an opportunity to address these incremental losses. 

At the same time, there are significant challenges with respect to the establishment of governance structures, financial mechanisms, capacities to assess and respond, to monitor and to enforce, as well as the technical understanding of complex ecological systems. Practitioners agree that all of these must be in place and in good order to deliver successful offsets.

Even in the face of all of these challenges, I think momentum will continue to build. A real test of the concept, and of the UK government’s appetite to embrace it, might come at an imminent Public Inquiry where 5,000 homes are proposed within a designated Site of Special Scientific Interest of national significance for the nightingale. Such areas are considered no-go areas of critical biodiversity value by many, but a package of measures to offset predicted losses, including replacement habitat creation, has been put forward as part of the development. I for one will be very interested to watch this unfold.

There are already lessons we can learn from the development of offsetting principles and their application to date. Starting with wetland habitat banking in the US over 30 years ago, and a 20-year history of experience in Australia, it is clear that a path to best practice can be achieved in perhaps as little as a decade. 

Many developing nations are now coming to practitioners for advice and for adoptable standards, having started along this path. Using the lessons learned, I think that biodiversity offsetting can become a force for good. But whatever our individual views, I believe we at Arup should be at the forefront of these debates and helping to shape the policies of the future, to do what we can to educate, to engage, and to learn from others in securing the global interests of biodiversity.