Radiative Forcing and Climate Sensitivity of Carbon Dioxide (CO2) Fine-tuned with CERES Data
Antero Ollila *
Department of Civil and Environmental Engineering (Emer.), School of Engineering, Aalto University, Espoo, Otakaari 1, Box 11000, 00076 AALTO, Finland.
*Author to whom correspondence should be addressed.
Abstract
An updated effective radiative forcing (ERF) value for constructing a simplified logarithmic forcing equation, and a transient climate response (TCR) value, are presented for CO2, CH4, and N2O. The results are based on line-by-line (LBL) calculations utilizing the HITRAN database and the CERES radiation flux data for fine-tuning. The ERF value derived when doubling the CO2 concentration from 280 ppm (2xCO2) is 2.65 Wm-2 which is in line with the instantaneous radiative forcing (IRF) values of climate models referred to by the IPCC. The difference between the ERF values comes from the stratospheric cooling effect. It is a question about an essential paradigm change of the IPCC approach. In the former 2xCO2 value of 3.7 Wm-2, its portion was about 5 %, and in the present value, it is about 30 %. According to this study, the same effect is 10 %. The updated TCR value is 0.7 ±0.15 °C.
Keywords: Climate sensitivity, radiative forcing, water feedback, climate sensitivity parameter, TCR, stratospheric cooling, ERF, positive water feedback