Although rapid population growth and the effects of climate change may soon see millions of people teetering on the brink of starvation, at this point in time there is enough food being produced globally to feed everyone on the planet. Despite this, wasteful practices, and the deft hand of international politics, ensure that many people are starving unnecessarily, and millions more struggle every day to secure a reliable food supply. For these people, life is an exhausting and stress-filled battle and the luxury of being able to choose whether or not to eat meat, milk or eggs, does not even arise and it would be ludicrous to suggest they adopt a vegan diet when their survival may depend on the small amounts of animal protein they can obtain.

As the world’s human population spirals out of control, soaring to nine billion or more by 2050, it appears that the race for the survival of our species is well and truly under way. Compounding the problem of too many people is the need to maintain the vast monocultures of wheat, rice, maize and sorghum that form the basis of today’s mass food production systems. It’s a risky business because crops grown in these circumstances are highly susceptible to both climate change and disease and if the worst-case scenarios come to fruition they may crumble very quickly, leaving the world’s poor, and many who wouldn’t consider themselves poor today, with nothing to eat.

Crop failures are expected to become increasingly common as climate change makes vast areas of today’s farmland too hot and dry to be productive.xviii How, in those circumstances, will we be able to justify feeding a third of our grain and soy crops to farmed animals, which then turn only about 17% of it into usable food, that is, as meat, when these same plant foods could be going to directly to starving people?

If tens, perhaps hundreds, of millions of impoverished people do run out of food—what will they do? Hungry people might riot; starving people cannot. They are too weak by that time. Most people, I assume, would try to get to a place where food was available. That may sound logical, but moving from, say, central India to central Europe, would be a very difficult thing to do. Given that a poor agricultural worker could even manage it, the real question remains: how would those people who have sufficient food react to unwanted, uninvited, mass migration on such a scale? They may not even have enough food to feed these multitudes and it doesn’t require a great deal of imagination to envisage the oceans and the land borders seething with the cadavers of poor people who had to flee their homes or face starvation.

A hotter, climatically volatile and more troubled world, without sufficient food or fresh water, is not a place where anyone would choose to be and nobody, not even the very wealthy, will be immune from its effects if we allow this to occur. The thought of such a world is, surely, sufficient reason for each of us who has a choice in the matter, to be moving away from animal agriculture as fast as we can in order to free up for human consumption, more of the grains and soy which are currently fed to animals. And while such a redistribution could be the difference between starvation and survival for many, but it would not be a permanent solution if the global human population continues to grow at it’s current rate, particularly when it seems certain climate change is going to reduce overall agricultural output. When this happens it is hard to imagine it will be any other than the poorest people—the subsistence farmers in sub-Saharan Africa, India, central Asia and China—who are hit hardest, the soonest and the worst.