As Schelling points out, our use of the term “geoengineering” is peculiar: “‘Geoengineering’ implies something unnatural. I would suppose, for example, that if the Earth’s atmosphere had always had a large amount of sulfur aerosols in the upper atmosphere and the aerosols increased and diminished from time to time and the carbon dioxide increased and diminished from time to time, and we began to have a greenhouse problem, it would be referred to as an imbalance in the ratio of the infrared-absorbing substances to the light-reflecting substances; reducing CO2 and increasing the sulfur would both appear unnatural. If we put carbon black on the Arctic ice to make it disappear, that would be considered geoengineering; if we just let it disappear because of global warming, that is not geoengineering. If we learn to make it snow more in the Sierras and the Rockies to enhance the water supply of California and Colorado and improve the ski slopes in the winter, that is not geoengineering; if we learn to make it snow in Antarctica, in order to store water there to reduce the sea level, that is geoengineering.” Thomas Schelling, “The Economic Diplomacy of Geoengineering,” Strategies of Commitment and Other Essays (Cambridge, MA: Harvard University Press, 2006), 45–50