The world is changing. The past five years have been the warmest since records began. Human activity, including the IT industry, is driving worrying climate change. The cloud gives us dazzling computational possibilities, and … potentially uses a lot of energy.The beauty of the cloud is that it makes it easy to run code, virtualised and scheduled for efficiency… but it doesn’t provide any guarantee that what’s running is useful. As climate change accelerates, where do we, as engineers, fit in? Are we part of the problem or part of the solution? How do we balance the needs of people against the need of the planet? Or can they be aligned? This talk discusses some of the trade-offs and provides a roadmap to figuring out the right thing.