it's the idea that has been at the heart of antonio nobre's work in the rainforest. we have a phenomenon that's so mundane. everybody say, "oh, a tree". but they don't realize, we don't realize what is happening inside. we don't realize how complex, how incredibly evolved. it took 400 million years to get to this point. t he tree is an incredibly complex machine that is able to pump water deep from the water in the soil, and pump it against gravity and keep going and going and going, all the way to the leaves. and release that in the atmosphere like if it were a geyser, and you don't see it because it is vapor, it is invisible. and as it does it, it's like an irrigation system in reverse. [chiwetel] water vapor alone will not turn into rain unless it is seeded. in the amazon, the forest produces its own rain by throwing out into the sky clouds of volatile organic compounds, which transform the vapor into raindrops. and the more rain the forest needs, the more particles the trees release into the atmosphere. [antonio] it's magical, in a sense. it's magical dust that s

[chiwetel] the question that has haunted antonio nobre's working life has come to haunt us all. [antonio] world war ii was nothing. what is coming our way is 1,000 times worse. [chiwetel] the filming of this story began in a very different world than the one we live in today. everything has changed. coronavirus has taught us that some warnings do come true. [antonio] it's absolutely essential that humanity, uh, understands what kind of risks we are running right now. i mean losing our habitat losing the planet where we have evolved it means really losing the capacity of continuing to live on earth. [woman] more than 15,000 scientists are sounding an alarm about climate change, they call it a warning to humanity. [indistinct chatter] [newscaster] there's a frantic effort underway tonight to find survivors. [man 1] the warmest year in the earth's recorded history and it's only getting hotter. [man 2] as we see the climate warming, the one thing that we're most clear about is you'll have more cold events and more heat events. [chiwetel] the world is experiencing a perfect storm of