CO2 Sensitivity

OPS-16 The following OPS summary appears dramatic at first glance. However, the atmospheric CO2 concentration extrapolations shown here (based solely on mathematics not technical science) are neither technically or economically possible. They do show the absolute worst case for CO2 emissions possible and still the theoretical temperature increase (due to CO2) does not reach dangerous levels. In fact, the temperature increase in 2100 will already be lower than the 1.5 °C target laid out in the 2015 Paris Accord (more on that in OPS-17). The CO2 climate sensitivity (1.35 °C per CO2 doubling) used in the example is also a worst case scenario. The 1.35 °C value assumes that all of the warming since the mid 1800s is due to CO2 (a physical impossibility since half of the temperature increase occurred prior to 1950 and most of the CO2 emissions occurred after 1950). CO2’s warming capabilities may ultimately be limited by the narrow bandwidth that CO2 absorbs and reemits energy (14 – 17 µm). Once the bandwidth is saturated, adding CO2 will not increase global temperatures and we may already be there. As I showed in OPS-8, temperatures over the last century and a half can be modeled by using just the Total Solar Irradiance (TSI, as a proxy for total solar forcing) and the Atlantic Multi-decadal Oscillation (AMO). Regardless, there is still NO (not one) CO2/Temperature dataset that shows CO2 has been driving the climate on any statistically significant time scale. CO2’s minor influence is lost in the natural influences (primarily solar forcings (direct and indirect)).