What is the leading cause of environmental destruction? It’s a question we’ve been faced with since the days of GCSE science, and it seems we still don’t know the answer. “Walk to school!” cried our teachers. “Change your light bulbs!” “Recycle!” We’ve debated endlessly about the advantages of renewable resources, and questioned the benefits of electric cars and nuclear energy. But I bet they never told you about cow farts.

The impact of animal agriculture on the environment is the controversial and little discussed subject matter of Kip Anderson and Keegan Kuhn’s documentary Cowspiracy. Billed as ‘the film that environmental organisations don’t want you to see’, Cowspiracy is also the film that the booming and monopolistic meat industry doesn’t want you to see.

The film is an exposé of the animal agriculture industry, uncovering it as the leading cause behind environmental devastation, producing more greenhouse gases than all the cars, trucks, and planes in the world combined. This may be hard to believe, but the methane gas produced by a cow’s digestive process is 86 times more destructive than the carbon dioxide emitted by vehicles. Not only does it carry a colossal carbon footprint, but also raising animals for food causes 91% of Amazon rainforest destruction, is the leading cause of ocean dead zones (areas completely devoid of life due to a dramatic decrease in oxygen concentration) and is a huge strain on the world’s water resources.

Everyone can remember the fracking furore that erupted a few years ago, polarising public opinion over the emergence of shale gas as a non-renewable resource. And rightly so; along with the health and environmental threats, a staggering 100 billion gallons of water is used every year in the USA alone for hydraulic fracking. However, raising livestock uses 34 trillion gallons. To add a little perspective: every time you eat a quarter pound hamburger, the water used to produce it is the equivalent of two months of showers (660 gallons, to be precise).

Having travelled around America interviewing members of environmental organisations and government water resource departments, Anderson reveals an uneasy truth: they’re hiding something from us. In an interview with the California Department of Water Resources, government officials rattle off spiel on using low-flow showerheads, water efficient toilets, and checking broken sprinklers for leaks, claiming that these are all areas “with a lot of room for conservation”. When the delicate question of livestock farming is brought up, officials throughout the film descend into a perplexed silence. You can almost see the beads of sweat forming on their furrowed foreheads as they frown, shake their heads, and gaze awkwardly up at the ceiling, before claiming “that’s not my area”. Case closed.

“The very people who are meant to be saving our planet are deliberately ignoring the devastating effect of animal agriculture on the environment”

Every day, it’s estimated that almost 100 plant and animal species are completely wiped out, as the rainforest is destroyed at a rate of an acre a second. 136 million acres of rainforest have been destroyed and replaced by pastures to graze cattle, and grow their feed crops. That’s 136 million acres of our planet’s lungs gone, directly affecting the air we breathe. However, environmental devastation doesn’t stop at the seashore. Scientists predict that we will see fishless oceans by the year 2048, due to ¾ of the world’s fisheries being either over-exploited or significantly depleted, and due to the horrific by-kill that results from unsustainable fishing. For every single pound of fish caught, there are five pounds of sharks, dolphins, whales and sea turtles ensnared in the net as well; between 40 and 50 million sharks alone are accidentally caught every year.

Of course, demanding a behaviour change as radical as eating less meat and dairy would put many people off environmental organisations and affect their bottom-line. Instead, they focus on switching your showerheads and turning the tap off when you brush your teeth. As Will Anderson, a former board of director for the environmental giant Greenpeace, says: “Environmental organisations are not telling you the truth about what the world needs from us as a species… it’s there for everyone to see, but the environmental organisations refuse to act… they are failing us, and they are failing ecosystems”. It seems that the very people who are meant to be saving our planet are deliberately ignoring the devastating effect of animal agriculture on the environment.

Having added up all the facts and figures, Anderson comes to the conclusion that a vegan, plant-based diet is the only way to sustainably feed the world, whilst addressing urgent issues like climate change, public health, animal welfare and the conservation of natural resources.

Although a utopian solution, it is true that if the whole world went vegan we wouldn’t need to extensively breed livestock the way we do now. If we didn’t need to breed them, we wouldn’t have to feed them, and therefore devote huge amounts of the earth’s land to growing their feed. And what would we do with all this free land? The choice is ours: we could either use it to grow food to feed all the hungry people of the world, or we could let it revert back to its original, natural state; whether that’s a rainforest or a habitat for a diminishing species.

Solar panels and wind turbines are all well and good, but they’re projected to take at least 20 years and over £11 trillion before they have a positive effect on the environment. We could stop eating animals today, get an instant impact and it would cost us nothing.

I’m not saying we should all go vegan right this instant, but it’s definitely food for thought.