As an increasing number of countries legislate for net zero, investors and lenders will need tools to identify risks and opportunities in the transition to a net zero economy. This requires forward looking, robust, decision useful and comparable metrics. The report provides a critical assessment of different approaches on a spectrum of sophistication, with a particular focus on portfolio warming metrics. The report sets out their key building blocks, initial views on potential best practice, and identifies the data needs and methodological questions that require further work to make these metrics robust.