This ammonite shell fossil spins faster the closer the cursor is to the center of the spiral. The spin speed increases according to the exponential function y=7.8e0.0175x. This equation is a best fit exponential regression curve derived from atmospheric CO2 concentration data measured at Mauna Loa Observatory from 1871 to the present, with the preindustrial average of 280 ppm subtracted. The integral of this exponential represents the total excess carbon added to the atmosphere due to anthropogenic imbalance of the carbon cycle, and therefore the total mass of carbon we must draw down to restore a preindustrial atmospheric CO2 level.
