CIEEM Urges Ministers Not to Undermine BNG

On

CIEEM is urging Ministers to resist any move to weaken Biodiversity Net Gain (BNG) as rumours intensify ahead of the Government’s long-awaited response to this year’s BNG consultations.

Reports suggest that the Government may remove the Small Sites Metric (SSM) entirely and introduce sweeping exemptions, including the possibility that BNG might only apply to developments over 0.5 hectares, and that large residential brownfield sites could be exempted.

CIEEM warns that such decisions would seriously undermine one of the UK’s most important nature recovery policies.

Serious risks to nature recovery and public trust

Concerns across the environmental sector are growing. If these rumours are accurate, the Government would be removing the very tools required to deliver on its legal and environmental commitments, and just days after publishing the new Environmental Improvement Plan (EIP25).

Coming alongside the Fingleton Review of Nuclear Regulations, which itself raised red flags over ecological understanding, the sector fears this may be another attempt to weaken environmental protections.

BNG has widespread public and cross-sector support and remains a flagship policy for mobilising private nature finance. Weakening it now would erode public trust, reduce investment and leave communities worse off.

Evidence shows large-scale damage from exemptions

Research by eftec highlights the stark consequences of raising the exemption threshold. Comparing <0.1 ha and <0.5 ha thresholds, the findings are clear:

  • Planning applications subject to BNG would fall by two-thirds, from 26,870 to just 8,892.
  • An extra 4,345 ha of land each year would be developed with no requirement to compensate for lost biodiversity.
  • The biodiversity unit market would shrink by £50 million annually, undermining private investment critical for nature recovery.

A higher threshold would also damage confidence in the emerging nature market, risk the viability of habitat suppliers, and create perverse incentives for developers to split proposals into smaller parcels to avoid BNG responsibilities. This would be disastrous for nature, planning authorities and communities.

Brownfield exemptions would harm wildlife

Rumours of a major exemption for large residential brownfield sites are particularly troubling. While brownfield land can be suitable for development, many such sites are biodiversity hotspots, especially for invertebrates. Removing BNG here would allow the loss of valuable habitats that support declining and specialist species.

Minor sites, major impacts

Minor developments have major cumulative effects. Small sites play a vital role in maintaining habitat connectivity, supporting urban wildlife, and delivering high-value green spaces for communities. Exempting them would accelerate the fragmentation of habitats in towns and cities and disproportionately harm already nature-poor neighbourhoods.

Removing small sites from BNG would also worsen inequalities in access to green space. This is an issue that the public cares deeply about as recent polling shows strong public support for nature protection and for BNG as a mechanism to improve local environments.

Undermining legal duties and environmental ambition

Weakening BNG would place the Government at odds with its:

  • Environment Act 2021 obligations
  • International commitments under the Global Biodiversity Framework
  • Newly published Environmental Improvement Plan (EIP25)
  • Delivery of Local Nature Recovery Strategies (LNRS)

Government cannot meet these commitments whilst simultaneously removing one of the primary mechanisms designed to deliver them.

A practical and widely supported alternative

CIEEM and partners have long advocated a practical compromise: a 0.1 ha exemption threshold.

This approach:

  • Exempts more than 50,000 of the smallest sites
  • Brings all sites above 0.1 ha back into scope
  • Closes loopholes for large developments
  • Ensures 20,552 additional hectares are protected through BNG
  • Doubles the value of the biodiversity unit market compared to the Government’s rumoured plans

This is the evidence-based and industry-supported solution that protects nature and enables responsible development.

A moment of truth for nature recovery

CIEEM warns that repeated attempts to dilute BNG – through exemptions and carve-outs – will cause the policy to fail.

The country is in the midst of a biodiversity crisis, with nature declining faster than ever. Now is the moment to strengthen action, not weaken it.

CIEEM calls on Ministers to reject damaging exemptions, maintain the integrity of BNG, and demonstrate global leadership on nature recovery.

We urge the Government to listen to the evidence, respect public and industry support, and back the practical 0.1 ha compromise that protects nature, communities and long-term sustainable growth.