Last year, ProPublica reporter Lisa Song traveled to a tropical expanse of rainforest in the state of Akre, Brazil.

It was her first time visiting the Amazon.

She was there to check on a claim that forests were being preserved as storehouses of carbon.

I became interested in Brazil because a lot of people were saying that this one part of Brazil,

this western state called Akre, had the best carbon offsets projects.

And so I decided it was worth going to Brazil to see what is happening in the place with the best of the best of these programs.

Offsets are a big part of climate goals for many countries and industries.

Right now, about 10% of the world's CO2 emissions come from ripping down tropical forests.

That's why in 2008, the United Nations created an offset program.

Polluting industries could buy carbon credits,

basically a certificate showing that a patch of forest had been saved in order to counterbalance

their own emissions. And in 2016, California's Clean Air Agency started considering these

forestry offsets to be one part of the state's climate program.

And what that means is if the Air Resources Board voted in favor,

then the door would be opened for allowing polluters in the state to offset or cancel

some portion of their carbon emissions by paying people in developing countries to not cut down

trees.

And in theory, the Amazon makes sense is a place to try to do that.

One reason environmentalists are so keen on saving the rainforest is because healthy forests are natural carbon sinks.

Biology 101.

Plants need carbon the way mammals like you and I need oxygen.

So they do a great job inhaling a lot of carbon through the process of, drumroll please, photosynthesis.

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