The UK government is making serious investments in new infrastructure as part of its post-pandemic recovery strategy, with £27 billion committed to road expansion, and a target of building an additional 300,000 homes per year. But it also has ambitious targets to halt and reverse wildlife declines by the end of the decade.
Addressing potential trade-offs between these objectives, the 2021 Environment Act made it mandatory (after a two-year transition) for most new developments in England to achieve a “biodiversity net gain” – a measure to ensure nature is left better off overall than before the project began. The government is now consulting on how to implement the legislation – but as it stands, we worry that the policy contains loopholes and will be nearly impossible to enforce.
The principle behind biodiversity net gain is simple, and has the potential to be a significant improvement on the current planning system. To get planning permission, proposed new developments will need to assess the biodiversity value of the site before construction, using a metric that accounts for the size, conservation value and condition of different habitats at the site. Developers also have to demonstrate that their actions will lead to overall biodiversity value rising by at least 10% after the project is completed.
As an example, if a housing development were to be built on a field, a developer could generate biodiversity gains by improving all the patches of habitat that remain within the project footprint, like grassland verges between the buildings or along pathways or roads. If these gains were not enough to achieve a 10% increase overall, they might buy “biodiversity offsets” from other landholders elsewhere to make up the difference. These are conceptually similar to carbon offsets, though with their own unique complications.
The idea of infrastructure and housing improvements that also lead to gains for nature is alluring. However, experience with similar policies (both overseas and in the UK) that allow developers to damage nature and then compensate for that damage – either on-site or elsewhere via offsets – have shown that, when it comes to realising real-world benefits for nature, the devil is in the detail.