In countries like Australia and the USA, the average person eats around 100kg of meat annually—almost double the amount we ate in 1950. Some of the leading causes of mortality in these countries are now heart disease, type 2 diabetes and certain cancers, which have been linked to high consumption of animal- based meat in thousands of peer-reviewed studies.

Infectious diseases like influenza can spread quickly in intensive animals farms. Not only can they decimate animal populations, they can infect humans, resulting in disease epidemics. Faecal bacteria from animals' intestines can also contaminate meat during the slaughter process; with four out out of five portions of raw chicken meat in Australia contaminated according to Food Standards Australia New Zealand.

A key source of antibiotic-resistance is intensive animal farming. In some countries, farmed animals, like chickens and pigs are feed 80% of all medically important antibiotics. These are often administered to promote rapid growth and prevent infection, rather than treat infection. The world's leading health authorities warn that overuse of antibiotics in animal agriculture risks a return to commonplace illnesses, injuries and infections once again becoming fatal.

We need urgent action on climate change to keep our ecosystems (and people) healthy. Addressing livestock emissions is critical to achieving this. Some estimates place livestock emissions on par with those of the global transportion sectors. According to Chatham House, without a reduction in consumption of products from livestock, it is unlikely that global temperature rises can be kept below the critical tipping point of two degrees Celsius.

Waterways and oceans are also polluted by livestock production. A factory farm with 5,000 pigs can produce as much effluent as a town of 20,000 people. Improper management or accidents can contaminate underground drinking water and run off into rivers and oceans. Agricultural run off is contributing to ocean 'dead zones' - water lacking in oxygen and, as a result, marine life

The UNFAO found that fish populations are struggling to keep up with demand for their meat. THey found that, as of 2013, almost one-third of fish stocks were overfished. In the process of commercial trawling for fish, sea life such as dolphins, seals, turtles, and sharks are often inadvertently caught.

Animal agriculture requires a vast amount of land, both for grazing and to grow feed for grain-fed animals. Procuring this land through logging has resulted in widespread biodiversity loss worldwide, including in the Amazon. Iconic Australian animals like the koala have had their habitats cleared in the state of Queensland where 91% of deforestation in recent years was for cattle grazing.

Farming animals is a resource intensive way of producting meat. On average, an animal requires six kilograms of plant protein to produce a single kilogram of meat. Animal agriculture also takes a toll on the world's fresh water supply, with 1,500L of water required to produce a single conventionally produced hamburger (roughly the same amount a human would drink in three years!).

Most livestock - about 70 billion individuals worldwide - are raised in factory farms. There is escalating community concern about animal welfare practices in intensive animal farming. Producing meat in a way that meets consumers' definition of humane can often be less cost effective, requiring more space and more veterinary resources. This leads to confinement of animals and routine surgical procedures without pain relief.