Re "Amazon deforestation" — those lands haven't been deforested because of the western country's consumption of meat, they've been deforested because people are starving, and they need to put food on the table, and be lifted out of poverty.
And countries, such as Brazil, are only now doing what the western countries have been doing all throughout the 19th and the 20th century. I know this sounds terrible, but you have no right to demand that Brazil stops the deforestation, and in fact you have no sway either, because you are not buying the result of their agriculture anyway.
If western countries want the deforestation of the Amazon to stop, the cold, harsh reality is that they should subsidize the price for it.
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As for making personal changes, if eating soy makes you feel any better, sure, do that, but stop shaming people for eating meat. Because in the large scheme of things, switching from meat to soy does mostly nothing for the environment.
The reason is that, going vegan, as an individual, only saves you a couple of $ in CO2 emissions per year. That's right. All of your efforts are only worth a couple of $ per year in CO2 emissions. And even if you think that's worth it, those emissions would be re-allocated to industry anyway.
Also, ironically, the behavior of people going green changes. If you have an electric car, for example, you might feel the need to ride it more, to make more trips. Because it's cheaper, and you've been a good citizen, you've earned it. And when that happens, and it does, your net emissions might not go as low as you'd think. Never mind that the subsidies for electric cars are yet again subsidies for the rich.
Go carless first, then we can talk about not eating meat ;-)
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Real change will come from technological progress. It always came from technological progress. Remember whales? Whales were not saved by political activism, by individuals refusing to use whale oil. Whales were saved because cheap replacements for whale oil became available.
Ironically, renewable energy might not be very green at all. Maybe we should address the fact that solar panels are super inefficient, taking up massive land use, and their recycling is super expensive. Instead of investing more in nuclear energy, money is being diverted on solutions that may in fact be worse for the environment than cleaner fossil fuels (e.g. gas).
We are currently unable to replace fossil fuels with cleaner alternatives, because "renewable" energy isn't up to snuff, and because of nuclear-phobia, which prevents investments in nuclear power.
But sure, let's all eat soy, that will save the planet.