The model starts in 1900. In the year 2000 you get the chance to set a new emission target and nominal time to reach it. Your aim is to have atmospheric CO2 stabilise at about 400 ppmv in 2100. From Sterman, John D. (2008) Risk Communication on Climate: Mental Models and Mass Balance. Science 322 (24 October): 532-533. Clone of IM-694 to run 1900 to 2100.