The current level of CO2 in the atmosphere exceeds 400ppm. This needs to be brought down to 350ppm, and soon, if we are to have a chance of maintaining a climate close to the one in which humanity and civilization arose. [1] The exact amount of CO2 needed to be removed is dependent on the amount of CO2 that we continue to put into the atmosphere. But, as modeled by Hansen et al. this can be (could have been ?) accomplished by removing 100 Gt of carbon in the 50 year period between 2031 and 2080. [1] We have only 2 proven means of significantly and economically removing CO2 from the atmosphere, planting trees and sequestering biochar.