Don't know how to save the planet? This is what you can do

Should we become vegetarians? Is it OK to fly? The author of There Is No Planet B, A Handbook for the Make or Break Years, answers the big questions

Our food makes up something like a quarter of our greenhouse gas footprint, and at the same time as cutting this we need to feed a growing population better than we are doing now, while rescuing our haemorrhaging biodiversity and avoiding an antibiotics crisis. There is no escaping the clear evidence that humans need to reduce their meat - especially beef and lamb - as well as dairy consumption. When we feed a soya bean to a cow, we get back only about 10% of the nutrition in beef, and it comes with a hefty dose of methane (a powerful greenhouse gas) and very likely some deforestation.