Vegans, please stop saying that animal agriculture causes 51% of greenhouse gas emissions. That is a made-up number from a bullshit study, which is not backed up by any peer-reviewed science or any climate scientist. Do your homework and read the news on the latest science.
Quoting a BS number just shows that you do not care enough about climate change to actually get the facts right. It shows that you do not read the news on climate science or the IPCC reports summaries. It makes you look bad and it makes veganism look bad.
Here's a very good article, written by a vegan, that quotes some sources that vegans desperately need to read: newint.org/blog/2016/02/1… 
This is not to say that livestock's contribution to environmental problems is not significant. In fact, the livestock industry is one of the most environmentally damaging businesses, as even FAO has recognized (fao.org/docrep/010/a07…).
But this does not mean that environmental problems would be magically solved if everyone became a vegan. In the case of climate change, a shift to a plant-based diet would significantly decrease emissions and has to be a top priority for any ambitious climate policy.
To say that the majority of carbon emissions come from livestock and that climate change would just disappear if everyone went vegan, however, is to overstate the case for veganism.
So, please, do advocate for a shift away from animal products as one of the things that societies must do to address climate change but don't ignore the fact that the problem is caused mostly by the burning of fossil fuels.
Vegans like to say that you can't be an environmentalist without being a vegan. I agree, but I add that you also cannot be a vegan without being an environmentalist. How can you care for animals and not for the environment they depend on?
And being an environmentalist implies actually engaging with the issues, following the science and working with fellow environmentalists to better understand how we can have a livable world. We surely need more vegan environmentalists.
I see a lot of "carnivores" and other proud meat-eaters quoting this thread to bash veganism. They should have read the whole thread, I've made it quite clear that the animal products industry is highly destructive and that the plant-based diet is the sustainable choice.
In fact, just today another study was published that shows how a shift to a plant-based diet, involving a reduction in the consumption of meat products of at least 90%, is essential to have a habitable planet: theguardian.com/environment/20…
In case anyone actually wants to read the whole thread and know more about the impacts of meat-eating on the environment, instead of just assuming that I'm attacking veganism, I'll leave some important references below.
