Estimating the Influence of Thermal Inertia and Feedbacks in the Atmosphere–Ocean System on the Variability of the Global Surface Air Temperature

Abstract

The modern climate of our planet is characterized not only by a trend caused by an increase in the concentration of greenhouse gases in the atmosphere, but also by fluctuations covering a wide range of frequencies and scales. The global climate variability based on the modeling results of the Coupled Model Intercomparison Project Phase 5 of the World Climate Research Program is characterized by significant differences between models. In particular, for the decadal-scale anomalies of the global and hemispheric temperatures, the standard deviation differences between models are as high as fourfold. However, in contrast to the differences in climate sensitivity between models, the causes of a wide range of the estimates of climate variability are still not entirely understood. The research in this paper is based on two-component energy-balance stochastic model. We analyze the sensitivity of interannual and interdecade variability of the mean global surface temperature (GST) to the feedback and thermal inertia of the atmosphere–ocean system under the assumption that the main external forcing factor is random fluctuations of the radiation balance at the upper boundary of the atmosphere. We estimate the influence of thermal inertia and feedback in the climate system on the interannual and interdecade variability (variance) of the GST and the spectrum of its fluctuations using the absolute and relative sensitivity functions derived in the research.