stunning beauty, unparallel veracity, the magic that is the rain forest. ♪ i traveled to costa-rica tout the health of these eco systems and the tall, dense jungles are known for warm climates, lots of rain and sheltering more than half of the world's plant and animal species. although rain forests comprise a small percentage of the earth, they do big things, in human terms they are a critical component to how we function. >> i love to think of the amazon, the rain forest as the lungs of the planet. >> reporter: they are more like the heart of the biosphere. >> reporter: our tale of the rain forest brings us to all places here, nasa laboratory in pasadena, california where scientists use techniques ranging from boots on the ground to satellites in the sky all to understand our living, breathing, green earth. ♪ the resent study by research scientists dave and josh says friend. >> what our study shows is the tropics really dominate the metabolism of our planet and from dominate the fossils from the atmosphere and really cleaning up the planet. >> reporter: research employed satellite map