Cloud providers are large, growing rapidly, and leading sustainable development of datacenters, although their total capacity is still a small proportion of the global datacenter footprint. In the next few years, all the major cloud vendors expect to reach 100% green energy in all their regions via power purchase agreements, and the local power grids worldwide are rapidly transitioning to green energy, so energy usage (scope 2) will become less material over time. Supply chain carbon footprint (scope 3) is already starting to dominate, as it’s dependent on low carbon buildings, manufacturing processes and delivery mechanisms that are on much longer decarbonization timescales. So far each of the major cloud providers has made different sustainability commitments, over different timescales, with different reporting methodologies and levels of detail. It's messy and confusing, and this talk will explain what is available now, public roadmap statements and commitments that have been made by AWS, Azure and GCP. Turning the problem around, what would a useful common standard look like, and what would developers and tools vendors be able to do with it?