 In what was arguably the largest ever environmental protest in the world, more than a million children across more than a hundred countries joined a global climate march demanding that governments act. The concerns of the young protesters are justified and supported by the best available science, wrote a group of scientists and scholars. The enormous mobilization shows that young people have at least understood the situation and we strongly support their demand for rapid and forceful action. In terms of our food supply, there are all sorts of little tweaks, like feed additives that can reduce cattle belching, but put all those tweaks together, according to the Pristise-Z-Lancet Commission, and we're only talking about reducing agricultural greenhouse gas emissions in 2050 by about 10%, whereas if we instead switched over to plant foods, we could reduce emissions by up to 80%. All those cow sheep and goat burps only represent a fraction of the greenhouse gas emissions from animal agriculture, so that's why, according to the IPCC, the official intergovernmental panel on climate change, becoming a so-called climate carnivore, just cutting down on ruminant products like beef wouldn't reduce greenhouse gas emissions as much as eating a healthier diet and limiting meat across the board, and the fewer animal products, the better. Which diet has the least environmental impact on our planet? A systematic review found that eating completely plant-based, maybe the optimal diet for the environment, but it's not all or nothing, even just cutting down on meat under an ounce or two a day could get you half the way there in terms of reducing greenhouse gas emissions. In terms of land use, a healthier diet like a Mediterranean diet may decrease your footprint by about a quarter, whereas even more plant-based diets can drop land use 50% or more. In general, diets that include meat require about three times more water, 13 times more fertilizer, more than twice the energy, and 40% more pesticides than those that don't. If you look even broader at the total environmental impact of omnivorous versus vegetarian versus vegan diets, looking not just at global warming, but ocean acidification, agricultural runoff, smug eco-toxicity of the water and soil, and direct human toxicity of the air we breathe, water we drink, and the soil we grow our food from, eating eggs and dairy. Maybe 9 times worse than plants, and eating eggs, dairy, and meat, maybe 17 times worse than sticking to plant foods. Oh, and as a bonus, we could feed an extra additional 350 million Americans, like an entire extra country's worth of people, more than if we eliminated food waste completely. Changing meat-eating habits would seem to be a relatively cheap and easy way to mitigate climate change in contrast to many other factors outside our control. However, surveys suggest few seem to recognize this option of eating less meat as a significant opportunity for helping. Research has shown that consumers often underestimate the impacts of meat consumption on the environment in general and on climate change in particular. The outstanding effectiveness of the less meat option as established by climate experts was recognized by only 6% of Americans sampled, and that's after they were prompted to assume climate change is actually happening. There's an overwhelming scientific consensus that climate change is real and we're driving it, but only about half of U.S. adults believe it. This is not by coincidence, just like the tobacco industry tried to subvert the overwhelming evidence that smoking caused cancer. Companies like Exxon orchestrated climate change denial campaigns that stalled meaningful efforts for decades. Certainly, environmental groups should know better, though, none of the highest-profile NGOs examined appear to want to feature the link between meat consumption and climate change. They're all aware of the evidence, of course, but evidently the science alone was not sufficient. It's like another form of denialism that can become like a negative feedback loop, where it's not popular to talk about, so you don't talk about it, so remains not popular to talk about, depriving the issue of the attention it needs to break out. And when they have messaged about it, environmental groups have tended to favor just asking for a moderate reduction in meat consumption, notable given the research demonstrating how much more powerful a lever it could be at the individual lever to go even further. But they don't want to be seen as telling people what to do, instead they're advocating for small changes, like turning off your computer monitor at lunchtime or printing double-sided. But the cumulative impact of large numbers of individuals making just marginal improvements in their environmental impact may end up constituting just a marginal collective improvement. Yet we now live at a time when we need to make urgent and ambitious changes.