There's an overpopulation problem alright, but not the one you might think. There are seven billion people on our planet, but times that number by 10 and you get the 70 billion farm animals driving the worst environmental crisis of modern times.
The impact of increased human numbers will come under renewed scrutiny this World Population Day (11 July). Rightly so; the faster we grow, the faster we are knocking down forests, killing off species and using too much water. Climate change is no longer a distant concept, but a tangible force already affecting so many people all over the world.
Overpopulation is too often seen as a standalone issue. This seems overly simplistic. Should we not rather address the specific things humans are actually doing? There is little doubt in the scientific community which single activity is to blame: the rise of animal agriculture, responsible for at least 14.5% of global greenhouse gas emissions. This is more than all of the world's transport - cars, buses, trains, planes, boats, ships - combined.
While human numbers are rising at roughly 1.2% a year, livestock numbers are rising at double that rate at around 2.4% a year. Farming animals emits high levels of CO2 through activities like feed production and the management of manure, which contains nitrous oxide, a substance estimated to have 296 times the climate change potential of CO2.
Cattle also naturally produce large amounts of methane, a highly potent greenhouse gas: your average cow produces around 700 litres of methane per day, the equivalent of a large 4×4 vehicle travelling 35 miles in a day. They also require huge amounts of land and water. It takes 15,500 litres of water to produce 1kg of beef, the equivalent of more than eight months of daily showers. It is also estimated that a vegan diet only requires about a third of the land needed for conventional Western diets.
What would happen if everyone in the UK abstained from eating meat for just one day per week? The emissions savings would equate to taking 5 million cars off the road. And what if everyone abstained for six days a week? That would be the same as taking every single car off UK roads.
If we continue ignoring the role of diet in climate change then the UK will have no chance of meeting its new commitment of cutting carbon emissions by 57% by 2032. Current policies which focus narrowly on the energy, transport and waste sectors fall a long way short of those required for the new target according to the government's official climate change advisors.
What we really need is a public education campaign on the disastrous environmental impact of farming animals. Most people in this country, I suspect, still have little idea that the production of meat, fish and dairy products is destroying the planet.
If the UK wants a policy blueprint then it should look to China, who recently announced its plan to reduce meat consumption by 50% to tackle climate change. Such foresight has to be applauded. Will a Western government ever table such a progressive climate initiative? It is hard to imagine one in the UK anytime soon.
A global shift to a vegan diet would see climate emissions decrease by 70% by 2050, according to a recent study by Oxford University, and result in a monetary saving of over $1trillion in costs linked to climate change and healthcare. Can we afford not to stop eating meat?