SIR – Global warming not Isis or Ebola is the biggest threat to humanity. The easiest way to reduce our carbon footprint is to go vegan. The environmental group Worldwatch says that animal farming accounts for a staggering 51 per cent of our greenhouse gas emissions.

The Amazon is being cut down and burnt daily to allow the planting of crops which will be used to feed farm animals. This creates carbon dioxide. The billions of farm animals on this planet produce slurry which releases methane. Methane is 23 times more powerful at trapping heat than carbon dioxide.

Finally the fertilisers used for the animal feed crops release nitrous oxide gas. This gas is 296 times more potent than carbon dioxide.

Max Hey, Fairway Grove, Bradford