“Implementation must accelerate to increase ambition across all front, taking an all-of-society approach to make progress towards the Paris Agreement goals. (UNFCCC, Synthesis Report of the First Global Stocktake, September 2023).” This book recommends a LCA and consumption/needs-based GHG accounting and reporting protocol as a city climate innovation, which the author hopes will be adopted as a bold global initiative for standard practices. This chapter suggests a protocol that may become the global guidance on new GHG accounting principles, defining inventory guidelines, identifying GHG emission sources, tracking emissions over time, reporting and verification. It does not provide specific guidance on GHG calculation methodologies and emission factors.