The temperatures on the CAT thermometer are ‘median’ warming estimates in 2100. This means there is a 50% chance that the calculated temperature will be exceeded if the given emissions pathway is followed. The ‘median’ is based on the probability distribution generated by the climate model (MAGICC7) when it takes into account uncertainties in our knowledge of climate sensitivity, the carbon cycle, and the effect of greenhouse gases, aerosols, and other factors that are used to calculate the temperatures