About a year ago, I mentioned there was a strong case for cutting back on meat-eating if we wanted to reduce the climate change gases that we are all responsible for, and new evidence confirms how important this might be.

I had pointed out that around one-fifth of the carbon dioxide, methane and nitrous oxide directly produced by mankind came from the rearing and eating of animals, but now recent studies indicate that this was too low. It seems that the original estimate did not include many supply-chain factors, including freezing and storage, and it is suggested that the figure could be as high as 40 per cent – far more than produced by all our transport activities.

It’s also recognised that there is greater demand for meat products as the world population moves from nearly seven to nine billion at the same time that living standards are rising. There is much truth in the statement that while the poor eat vegetables, the rich eat food that eats vegetables.

Recently, the World Bank has suggested that replacing livestock products with better alternatives would be more effective in reducing climate change emissions than all the attempts to replace fossil fuels with renewable energy that will be announced at Copenhagen.

Even though there are far more vegetarians in Western society than 50 years ago, it’s not a straightforward matter. Practices range from veganism, eating no animal products at all, and certainly avoiding eggs and dairy products, to those who avoid animal meat but like their milk, cheese, butter and omelettes, while some just eat white meat.

Our relationship with animals is complex, with some religions avoiding pig products, and another not eating beef, even though the animal is venerated and provides milk, butter, fuel, motive power and, of course, methane. The problem for milk-drinking vegetarians would be what to do with the surplus uneaten male animals, though with fewer beasts there should be soya feedstuff left over to provide soya milk which has less fat than cow’s milk and about the same protein.

An allied problem is the annual carbon footprint of our pets, with a dog producing more than a 4x4, and a cat the same as a small saloon car. Perhaps a first step would be to not replace Fido and Tiddles when they die, and to go meat-free once a week, like Ghent in Belgium where Thursday is ‘veggie day’.