Advisers demand airlines pay for carbon removal to expand Heathrow

The plan requires that the question of Heathrow’s growth be replaced by a formula: expansion permitted in proportion to carbon removed, removal purchased by the airlines, the atmosphere restored to balance by contract. But the practice of managing an airport, and indeed of managing an economy that depends on one, encodes a knowledge of contingency, sequencing, and adjustment that no formula of this kind can capture, and the people who possess it - the schedulers, the route planners, the engineers who know what a third runway actually does to holding patterns over west London - were not consulted in the drafting of the condition, only in its eventual compliance.

The Climate Change Committee’s proposal is, in its own terms, admirably tidy. It treats the expansion of Heathrow as a technical problem with a technical solution: emissions occasioned by additional flights offset by removals purchased by the airlines who occasion them. This is Rationalism in a mild and well-intentioned form, and I do not say it is foolish. I say only that it mistakes the character of the activity it proposes to govern. Aviation policy is not an equation to be balanced once and left; it is a continuing adjustment among airlines whose businesses depend on marginal profitability, a government whose credibility depends on being seen to take climate targets seriously without derailing an infrastructure project it has already sunk political capital into, and a technology of carbon removal that does not yet exist at the scale the condition presumes.

Here is the gap. The condition asks airlines to pay for removal capacity that is, at present, largely notional - direct air capture and the like remain expensive, unproven at scale, and thinly distributed across the world. A rule requiring payment for removal treats removal as a commodity already priced and available, when what actually exists is a set of pilot projects and a market still discovering what a tonne of removed carbon should cost. The airlines will pay something; whether what they pay corresponds to any removal actually occurring, on any particular date, is a matter the formula cannot guarantee, only require.

What the tradition of British aviation regulation has generally understood, and what this condition risks forgetting, is that a target imposed on paper acquires its meaning only through the accumulated judgement of regulators who adjust it as the removal technology matures or fails to. The Committee has stated a principle. The airlines will now discover, flight by flight, contract by contract, what the principle actually costs them to satisfy - and the government will discover, runway by runway, whether a rule written for an atmosphere it cannot yet measure was ever really a rule at all, or only a hope dressed as one.