Understanding and Implementing the Like-for-Like Principle

To effectively halt global warming, net-zero CO₂ must be sustained in the long run. This requires a state of “durable net-zero,” where carbon fluxes are rebalanced with the appropriate removals, and carbon pools are stabilised. The Like-for-Like (LfL) principle establishes minimum requirements for employing carbon dioxide removal (CDR) to durably neutralise residual emissions:

• Any remaining fossil CO₂ emissions can only be neutralised using permanent CDR.
• Biogenic removals can be used to neutralise residual biogenic emissions, such as those from agriculture, land use change, or the temporary warming effect of methane matching their duration.

By creating robust rules for neutralisation, the LfL principle:

• strengthens the incentive to cut emissions
• clarifies the use cases of temporary removals
• creates the demand for permanent CDR to scale up to the relevant volumes.

The implementation of the LfL principle faces a series of challenges in the short term, among them limited supply and the high costs of permanent removals. Carbon Gap recommends enshrining the LfL principle in legislation now and creating mechanisms for a gradual implementation.

In this brief, we examine the origin of the LfL principle and its role in defining net-zero strategies towards durable net-zero. We analyse the two parts of its definition - on carbon fluxes and GHG lifetimes - to show that they are complementary and explain that they apply differently to the different GHGs in a meaningful approach to matching removals with residual emissions. With this review in mind, we explore the challenges posed by its implementation and provide a series of recommendations to enshrine it in legislation while progressively creating the conditions required for its full implementation.