(To be exact, farmers in Britain use four times as much carbon per tonne of New Zealand lamb than farmers in New Zealander. How can shipping meat half way round the world create fewer "food miles" than locally rearing it? Well when you want to understand the real cost to the environment it's not enough to calculate "food miles" you have to look at other factors, and when it comes to raising lamb the UK uses more nitrogen fertiliser for pasture land by a factor of more than 13.