One of my favorite scientific realizations is the idea that all of the trees and plants we see are basically solidified air. Photosynthesis is the process of using energy from light to turn air (carbon dioxide) and water into sugar, and that sugar is then used both as fuel and as a structural building block to make more plant.

I've wondered how much photosynthesis actually happens on earth, and recently looked up the answer. Current best estimate: 150-175 petagrams per year, or about 0.45 peta...