An indoor cannabis farm in CaliforniaShutterstock/Liudi HaraIndoor cannabis cultivation in the US uses more energy than all outdoor agriculture in the country combined. This generates a large and growing emissions footprint that often goes unrecognised.Consumers are led to believe that this is natures medicine and that its green in every sense of the word, says Evan Mills at Energy Associates, a consultancy in California. Theres lots of greenwashing.More than 60 per cent of the 24,000 tonnes of cannabis grown