Why we publish the flat years in the plan

A path with no flat years has not been costed

Decarbonisation trajectories published by companies tend to share a shape: a smooth decline from today to the target date, each year a little better than the last. Almost nothing behaves like that. Abatement arrives in lumps, when a lease ends or a boiler fails or a contract comes up for renewal, and between those moments very little moves.

So the curves that matter have steps in them, and the flat parts are the honest bit. A plan that bends every single year is usually a plan where the arithmetic was drawn backwards from the target.

Why the flat years happen

Almost always for reasons that were foreseeable, which is precisely why they belong in the plan rather than in next year's explanation. A lease with ten years left on it was always going to run those ten years, and writing that down in advance costs nothing except the appearance of momentum.

• An asset with ten years left on it that nobody is going to replace early
• A grid that decarbonises on its own schedule, not on yours
• A supplier switching fuel in 2029 because that is when their plant is rebuilt
• Growth, which adds emissions while the intensity figure improves

What a marked flat year buys you

Credibility in the fourth year, mostly. A board that was told in advance that 2029 would not move does not treat 2029 as a failure, and nobody has to go looking for a definitional change that makes the line behave.

Reporting a flat year as flat costs less credibility than a reorganised baseline that makes the line bend. Clients rarely believe this until the second year.

The alternative is a restatement

Because the pressure to show movement does not disappear. If the number will not move, something else does: the boundary, the base year, the factor set. Each of those is a restatement waiting to be noticed, and the person who notices it will be the one reading the report most carefully.