The modest outcome of the climate conference in Paris makes it clear that if humanity is going to decelerate, let alone reverse, carbon emissions it will require a change in the behaviour and expectations of billions of people, not just governments.
The world population clock is growing by more than 120,000 people a day. By the time the global population reaches the projected nine billion in 2050 there simply will not be enough water and land to produce meat for that population. Change has to come.
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Which leads me to introduce Tuyu, the water buffalo.
Two years ago, Tuyu was found on a road when she was a tiny calf, on Melville Island, north of Darwin, where buffalos roam free. She was taken to nearby Tiwi College and hand-reared. She became the school's mascot. Tuyu was let out to roam when school was out, and at dusk she would let herself back into her pen.
When I went to Tiwi College last month, visiting Tuyu was a morning and evening ritual. She always came over for a nuzzle.
On the Tiwi Islands, buffalo are regarded as a free protein by the locals. When a ute-load of young hunters drove past the school recently, there was anxiety about the most friendly buffalo on the island.
A sign was quickly produced and erected, with a drawing of a buffalo under the bold word Tuyu. It said: 'No shooting on college property. Pet buffalo wandering on college grounds'.
If anything were to happen to Tuyu, Tiwi College would go into mourning.
Most Australians would relate to that. Almost two out of every three households include at least one animal, 33 million of them, according to the RSPCA. They are part of the family for numerous reasons. This is reflected in our advertising.
Yet the majority of Australians also have a selective amnesia about how the meat on their plate got there.
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Every cow, pig, sheep and chicken is a sentient being. If hand-reared, most will regard themselves as part of the family unit. Even water buffalos can be gentle with people.
After decades of enjoying meat, the sentience of animals got to me. I don't want any part of their slaughter. The first to go was veal. Then beef, pork, lamb and, recently, chicken. Now even dairy is on the way out. (What do you think happens to all the male calves on a dairy farm?)
Traditionally, my position is not the most practical one. Until recently, meat has always been the most efficient way of producing protein for human consumption and nutrition.
Now my position is entirely practical. Raising animals, especially cattle, for protein is increasingly problematic given the sheer scale of carbon emissions by the livestock industry.
Raising livestock is responsible for 14.5 per cent of global greenhouse emissions, according to the United Nations. This is comparable to the emissions of the entire transport sector. Raising beef is extraordinarily profligate in terms of land and water per kilo of meat produced for the table.
And I think most meat-eaters would be repelled by a visit to an abattoir.
A reduction in meat consumption by the world's population would thus have an enormous impact on greenhouse emissions.
This is why I was pleased to see Arnold Schwarzenegger turn up at the Paris climate conference. He wasn't there as a sideshow. He was there as the former governor of California - the world's eighth-largest economy – and an advocate for reducing carbon emissions.
He delivered speeches and interviews urging people to start cutting back on meat consumption, pointing to the numerous and growing protein alternatives. Even in the macho world of body-building, where he made his name, there are plenty of vegetarians.
There is structural change underway. In the world's biggest food market by value, the United States, a sweeping shift is taking place in consumer sentiment towards organic and free-range foods. This shift has been led by the Millennials.
The market is further evolving with the rapid development of non-meat protein products which have the smell, taste and texture of meat.
One company, Beyond Beef, based in Schwarzenegger's adopted home town, Los Angeles, produces a range of meat simulants that are 100 per cent, additive-free, soy and pea protein.
Founded by Ethan Brown in 2009, Beyond Beef has attracted powerful venture capital backing, notably from Microsoft founder, Bill Gates. The company released its first product, 'Chicken-Free Strips', in 2012 and now has 16 products on sale in thousands of stores throughout the United States. Its 'Beast Burgers', 'Beefy Crumble' and 'Italian Meatballs' are all made of pea protein. Its 'Southwest Style Tenders' are a soy and pea protein mix.
Another American protein pioneer, Impossible Foods, is even more ambitious. It is producing not just meat simulants but cheese simulants. Its signature product is a cheeseburger made entirely from plants.
Impossible Foods is based near Silicon Valley where non-meat protein is regarded as a major industry disrupter. The technology of protein is generating significant investment from the world's centre of venture capital.
The founder of Impossible Foods, Dr Patrick Brown, said the boom in investment in plant-based protein is driven by the certainty that the world cannot provide a meat-based diet for billions more people without unsustainable increases in global greenhouse emissions, water consumption and land depletion. His mantra: "Animal farming is absurdly destructive and completely unsustainable."
Until now, cheap food has been sustained by the suffering of billions of animals. Each animal pays a high cost for a low price-tag.
There are now alternatives and new imperatives. On every level - climate change, sustainability, scientific innovation, and the immorality of cruelty - the future of protein is not meat.