 Good morning, we're here today at the Susquehanna-Shale Hills Critical Zone Observatory, and all around me processes are removing carbon dioxide from the atmosphere. Above me, in the trees, photosynthesis is occurring, and that process removes CO2 from the atmosphere and converts it to oxygen that we breathe. If it weren't for photosynthesis, the Earth would not be habitable. And it's going to be incredibly important moving forward that we preserve the forests of the world because of their role in photosynthesis and removal of CO2. There's another process that's going on near me here in Shale Hills, and that process is called weathering. Weathering is a much slower process that includes the breakdown of rocks below the surface by chemicals and bacteria, and the mixture of those breakdown products with the degradation of organic material that's produced by trees and plants, and the mixture of the degraded organic material and the minerals that are produced by weathering of rocks produces soil. And you can see a beautiful example of a soil profile right behind me. So in this module, we're going to learn in detail what happens to the CO2 that humans put into the atmosphere and what will happen in the future as we continue to put more CO2 in.