Biodiversity offsetting

Biodiversity offsetting is a system used predominantly by planning authorities and developers to fully compensate for biodiversity impacts associated with economic development, through the planning process. In some circumstances, biodiversity offsets are designed to result in an overall biodiversity gain. Offsetting is generally considered the final stage in a mitigation hierarchy, whereby predicted biodiversity impacts must first be avoided, minimised and reversed by developers, before any remaining impacts are offset. The mitigation hierarchy serves to meet the environmental policy principle of "No Net Loss" of biodiversity alongside development.^[1][2]

Individuals or companies involved in arranging biodiversity offsets will use quantitative measures to determine the amount, type and quality of habitat that is likely to be affected by a proposed project. Then, they will establish a new location or locations (often called receptor sites) where it would be possible to re-create the same amount, type and quality of habitat. The aim of biodiversity offsets is not simply to provide financial compensation for the biodiversity losses associated with development, although developers might pay financial compensation in some cases if it can be demonstrated exactly what the physical biodiversity gains achieved by that compensation will be. The type of environmental compensation provided by biodiversity offsetting is different from biodiversity banking in that it must show both measurable and long-term biodiversity improvements, that can be demonstrated to counteract losses. However, there is so far mixed evidence that biodiversity offsets successfully counteract the biodiversity losses caused by associated developments, with evidence that offsets are generally more successful in less structurally-complex and more rapidly-recovering habitats such as loss of biodiversity simplified wetland habitats.^[3] For biodiversity offsets to successfully compensate for the loss of biodiversity elsewhere, it is necessary that they demonstrate additionality (i.e. the deliver an improvement in biodiversity that would not otherwise have occurred). While there are individual case studies of offsets that have successfully delivered additional outcomes,^[4] other evaluations of large-scale biodiversity offsetting markets have demonstrated serious additionality shortcomings.^[5]