British officials working on plans to tackle climate change have highlighted a new threat to the planet: millions of unnecessary emails sent every day, including those that say nothing more than “thanks”. The Financial Times reports that the carbon footprint of an email comes from the electricity that is used to power the devices on which it is written and read, the networks that transmit the data, and the data centres that store it. Experts estimate data centres currently account for less than 0.1 per cent of the world’s carbon footprint, a small figure compared with the 20 per cent blamed on cars. However, emissions from data centres are growing because of increased use of online media such as video calls, games, and streaming.