Sam Eaton:

Nobre says total deforestation in the Amazon is only a few percentage points shy of triggering an ecological tipping point that could cause more than half of the Amazon forest to die off, an event, he says, that would release so much carbon into the atmosphere, that it would send global warming into hyperdrive.

But as the world's demand for meat and the soybeans used in animal feed only grows, Nobre says, if nothing changes, reaching that tipping point is just a matter of time.

The Amazon Basin has been locked in this fierce battle between conservation and indigenous rights on one side and the extraction-based economy on the other. It's basically a losing game, which is why many are asking, is there a third way for the Amazon, one that values a forest left standing like this one as a global public good? And how do you create economic potential, so that the people living within the forest see this as much more valuable than clearing the land?

At the Mundurukus' village, the chief rings a bell to announce a meeting. The occasion is the arrival of agronomist Paulo Nunes. His donor funded program called Sentinels of the Forest has enabled indigenous groups like the Munduruku to turn the Brazil nuts that grow wild in the forest into a badly needed cash crop.