New publication on the carbon budget concept

29 April 2024

Photo: marcin at pixabay

The concept of the carbon budget has gained prominence over the last decade. It states that the global mean temperature (GMT) increase is roughly linearly dependent on cumulative emissions of CO2. The proportionality is measured as the transient climate response to cumulative emissions of carbon dioxide (TCRE).

On April 18th, Vito Avakumović published a paper entitled “Carbon budget concept and its deviation through the pulse response lens” in Earth System Dynamics. In this paper, Avakumović examines the deviations of the carbon budget from the strict linear relationship implied by the TCRE through the lens of a temperature response to an emission pulse (i.e., pulse response) and its relationship with a nonlinear TCRE. He distinguishes between two sources of deviation: emission scenario and climate state dependence.

In a setup chosen in Avakumović’s paper, the deviations stemming from emission pathway choices are less than 10% of the overall temperature increase and gradually diminish. Furthermore, the scenario-dependent effects of a reduced-complexity climate model were replicated using the pulse response as a Green's function, confirming that the behavior of scenario-dependent deviations can be explained and predicted by the shape of the pulse response. Additionally, it is demonstrated that the pulse response varies in accordance with climatic conditions, thereby elucidating the state dependency of the carbon budget.

This paper paves the way for future investigations and applications with other and more complex models.