Model for Estimating the Transient Response of the Global Mean Surface Temperature to Changes in the Concentrations of Atmospheric Aerosols and Radiatively Active Gases

A two-component energy-balance climate model (EBM) is considered, which allows estimating the transient response of the global mean surface temperature (i.e., the Earth climate system response) to radiative forcing due to atmospheric aerosols and radiatively active gases in accordance with the specified scenarios of their atmospheric content. An expression for the impulse response function of EBM is analytically derived. The response of the climate system to arbitrary external radiative forcing is calculated as a convolution of two functions - an impulse response function and a function describing the radiative forcing. The comparative analysis of the numerical calculation results for two idealized scenarios of radiative forcing (step function and linearly increasing radiative disturbance) and the exact solution analytically derived shows a fairly high accuracy of the approach. Using the impulse response function, we estimate the response of the global mean surface temperature to radiative forcing specified by several scenarios of an increase in the concentrations of greenhouse gases (four RCP scenarios) and volcanic aerosol (1991 eruption of the Pinatubo volcano). Since the technique suggested for estimating the transient climate response to radiative forcing is quite accurate and computationally inexpensive, it can be used as an express analysis tool for estimating the climate system response to arbitrary radiative disturbance caused by natural and anthropogenic aerosols and radiatively active gases including greenhouse gases.