There's a lot of ways to try and solve this, good and bad, and if Brazil was a super rich country, just strong arming them or shaming them into fixing their shit would probably be morally justifiable but...they're not. By far the easiest way is to give them positive incentive to care about the amazon as much as the rest of the world cares for it. It would be a heck of a lot easier to toss a ton of cash their way, and tell them "if you fuck it up, all of this money is going away". It's not a perfect solution, but logistically speaking, it's by far the easiest that may work.