Phase Shift between Changes in Global Temperature and Atmospheric CO2 Content under External Emissions of Greenhouse Gases into the Atmosphere

Abstract

The phase shift between changes in the global surface temperature T_g and atmospheric CO₂ content \({{q}_{{{\text{C}}{{{\text{O}}}_{2}}}}}\) has been shown earlier not to characterize causal relationships in the Earth system in the general case. Specifically, the sign of this phase shift under nongreenhouse radiative forcing changes depends on the time scale of this forcing. This paper analyzes the phase shift between changes in the global surface temperature T_g and the atmospheric CO₂ content \({{q}_{{{\text{C}}{{{\text{O}}}_{2}}}}}\) under synchronous external emissions of carbon dioxide and methane into the atmosphere on the basis of numerical experiments with the IAP RAS climatic model and a conceptual climate model with carbon cycle. For a sufficiently large time scale of external forcing, the changes in \({{q}_{{{\text{C}}{{{\text{O}}}_{2}}}}}\) lag relative to the corresponding changes in T_g.