October 2025

How can policymakers begin to identify the policies needed now and in future to advance the transition in a given sector, and communicate the rationale to government ministers and others whose support may be needed? This report provides a practical framework to help identify the policies needed now, foresee those likely to be useful in future, and inform strategies for effective transitions.  

The report provides two overarching principles for transition policy. 

The first principle is: First build the new zero-carbon technology systems, then break the old polluting ones. People can only stop using an old technology when a new one is available and affordable. New solutions must be invented, introduced into the market, and scaled up, before old systems can be phased out. Crucially, policies that focus on developing new solutions and constructing new systems benefit from self-amplifying feedback effects, early in the transition.  

The second principle is: Match the policy to the stage of transition. There are distinct stages in the process of building new technologies and the infrastructure and social systems they need, and dismantling the old systems. Each stage involves different problems, which different policies can help to address. 

These principles are illustrated by 18 case studies, with examples from historical transitions such as those from horses to cars, and from wells to piped water, and examples from recent low-carbon transitions across power, housing, transport, heavy industry and agriculture, from countries around the world. The report also includes principles for effective policy design at each stage of the transition.