Costing the Earth - Virtual Warming

Every twitter, Facebook posting and You Tube video viewed has a carbon cost that is becoming increasingly dear, as our use of computers grows exponentionally. The expanding digital cloud contributes 2 per cent of global emissions of carbon dioxide, about the same as aviation, and it's rising. The high energy demands of the massive data centres needed to store all our information are of growing concern to both the government and industry. But how can they be made greener and more efficient? Costing the Earth investigates.