Does net-zero CO2 stabilize the climate? - On the contributions of the remaining climate forcing

The Paris Agreement long-term temperature goal (Paris Agreement LTTG) aims to limit global warming to well below 2ºC, if possible to a maximum of 1.5ºC. To understand how this goal could be accomplished, idealized scenarios have been explored in the past years, with a special focus on pathways for reaching net-zero CO₂ emissions. 

Non-CO₂ forcing is, however, known to contribute to a decrease in the remaining carbon budgets related to the Paris Agreement LTTG (e.g., Mengis & Matthews, 2020). A full picture regarding this benchmark can therefore only be painted when including the effects of aerosols, non-CO₂ greenhouse gases and land use changes. These forcings along with the zero emissions commitment to CO₂ will define whether temperature is able to stabilize once CO₂ emissions decrease.  

To explore individual effects from anthropogenic non-CO₂ forcing agents, their respective contributions to the Paris Agreement LTTG scenarios (Rogelj, et al., 2019) is estimated and put into relation. We will present results primarily on the impacts of aerosols and land use change representation as well as their effects on the carbon cycle and climate by simulating LTTG scenarios using an Earth system model of intermediate complexity (UVic ESCM, version 2.10, Mengis et al., 2020). The climate response in these all forcing net-zero CO₂ emission scenarios will provide us with relevant insights concerning allowable emissions for temperature stabilization.

References: 

Mengis, N., Matthews, H.D. Non-CO₂ forcing changes will likely decrease the remaining carbon budget for 1.5 °C. npj Clim Atmos Sci 3, 19 (2020). https://doi.org/10.1038/s41612-020-0123-3

Mengis, N., Keller, D. P., MacDougall, A. H. et al. Evaluation of the University of Victoria Earth System Climate Model version 2.10 (UVic ESCM 2.10). Geosci. Model Dev. 13, 4183–4204 (2020). https://doi.org/10.5194/gmd-13-4183-2020  

Rogelj, J., Huppmann, D., Krey, V. et al. A new scenario logic for the Paris Agreement long-term temperature goal. Nature 573, 357–363 (2019). https://doi.org/10.1038/s41586-019-1541-4