Early outcomes of England’s new biodiversity offset market
Our new paper from Oxford Uni’s Biodiversity Net Gain team out now, led by BNG superstar Natalie Duffus. Natalie conducts the first academic analysis of what’s actually happening in the off-site BNG market. Natalie’s painstakingly assembled all of the available info on the off-site register, manually creating shapefiles from the drawn maps on the BNG register, identifying parcels of habitat from the aggregate statistics presented on the register as far as possible, & tracing each habitat transaction to its original development site across tens of LPA planning portals where possible. We have the habitat bank data & transactions data up to May 2025; & the first year of transactions (Feb 2024-2025) traced to demand sites.
The highlights:
– In the first year & and quarter (i.e. up to May 2025), just ~2% of the BNG off-site network sold (58/~3000ha listed on the register)
– 38% of total unit demand comes from sites <1ha in size
– 44% of all units are other neutral grassland, followed by mixed scrub & lowland meadow
– Most woodland & wetland on the register is enhancement, so it’s not adding much new woodland or wetland to the conservation estate, but it is adding lots of new grassland
– Nat conducted a complementarity analysis to see if the BNG network is protecting types of habitat that are not being protected by the existing network of conservation sites in England. It is – it’s protecting much more grassland, which is underrepresented in the existing network of conservation sites.
Implications:
– **Respond to the BNG small sites consultation**! That consultation threatens to remove up to 38% of the demand from a system that is already profoundly demand-constrained
– Government should consider doing the thing we’ve been building the evidence base for for 5 years – crack down on unenforceable on-site gains & divert more demand through the off-site BNG market, or the government has absolutely no chance of achieving the finance goals of the Nature Markets Framework. We have *decades* worth of demand going unsold on the BNG register which could revert to agriculture if nobody buys it (& most will go unbought without the government stimulating demand)
– Preliminarily, BNG appears to be delivering mixed outcomes for conservation: it’s producing fairly homogenous grasslands, but also grasslands are under-protected, so is adding something to the conservation estate that is of value. We’re planning on looking into these results further because there’s a lot of nuance here.
Led by Natalie Duffus, with co-authors Sophus zu Ermgassen, Owen Lewis and Richard Grenyer
