The first environmental issue that I became aware of when I was a kid was the need to "save the rainforest". We've been cutting down huge swaths of rainforest all over the world for the past 60 years or so. Trees are cut for their timber, land is cleared for farming, oil drilling, and mining.
The conventional thought has been that once rainforest is lost, it's gone forever. I remember reading about the rainforest soil in grade school and how it would quickly get blown away after the land was deforested. Soil takes an incredibly long time to develop, so once a farm or clear cut took down rainforest, it was gone for good.
Willie Smits wasn't satisfied with that answer. He brought his obvious genius to bear on the problem of regrowing the rainforest and has had some nearly miraculous results in Borneo.
This video of his 22 minute presentation from the TED Conference
makes it pretty clear that we can regrow rainforest, something that has could have hugely positive benefits for the world. Rainforests are the planets lungs, sucking up CO2 and pumping out sweet, sweet oxygen. The clouds covering rainforests bounce more sunlight back to space than dark clear cut land and their streams and rivers are important filters, cleaning water that keeps billions of people around the world alive. Well managed rainforests can provide jobs for locals in the form of sustainable agriculture and eco-tourism.
22 minutes is a long time in these days of the two minute YouTube blip, but it's well worth it. Check it out.