Biodiversity Net Gain is what happens when we mistake the measure of a thing for the thing itself. Schools become league tables, hospitals become waiting-time targets, digital culture becomes engagement statistics; eventually a living landscape too becomes a number in a spreadsheet. The problem is not measurement. Of course we should measure ecological damage and recovery. The problem begins when the metric acquires sufficient authority to make unlike things appear interchangeable: sever this habitat here, manufacture enough units there, apply the approved multipliers and, with a little actuarial magic, destruction becomes a net gain. This is the trap we find ourselves in in Elmbridge right now as the council faces the combined pressures of developers gobbling up land and a government keen to release the handbrake on planning controls.
But nature is not fungible. A landscape is an accumulation of relationships between soil, water, species, seasons and time, some understood and many not. Its value may lie precisely in its continuity, its position between other habitats, or in things the metric measures badly or hasn’t noticed at all. Hugh Warwick’s objection to the old claim that Britain has plenty of countryside applies equally here: acreage tells you very little about the significance of the particular acreage you are proposing to lose. BNG can tell us something useful about a scheme. The absurdity begins when a positive score is allowed to tell us the scheme is therefore good. The score is not the game.
