and there's another vital service that trees and plants provide: photosynthesis. vegetation reduces the greenhouse effect by taking carbon dioxide out of the atmosphere. a measure of what restoring nature can do has been shown here on china's loess plateau, where farmers have continued to prosper despite the worst drought in decades. >> [singing] >> since the beginning of the project, the soil that nurtures their crops has been accumulating organic material from plants and animals. this holds the moisture and contains carbon. what's interesting about this is all these root materials, all this other stuff, this is organic materi. and this organic material is mixing together with the loess, the geologic soils here, and is making a living soil. this is where the moisture resides. yesterday it rained and there's still moisture in the soil. this is where the nutrients are recycled so that each generation of life emerges here. and this is where thearbon is. what's interesting about this, they made this field, this is new, so they're helping to sequester carbon. living s