EGU21-819
https://doi.org/10.5194/egusphere-egu21-819
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Carbon cycle response to temperature overshoot beyond 2 °C – an analysis of CMIP6 models

Irina Melnikova1,2, Olivier Boucher1, Patricia Cadule1, Philippe Ciais3, Thomas Gasser4, Yann Quilcaille4, Hideo Shiogama2, Kaoru Tachiiri5, Tokuta Yokohata2, and Katsumasa Tanaka2,3
Irina Melnikova et al.
  • 1Institut Pierre-Simon Laplace, Sorbonne Université / CNRS, France
  • 2National Institute for Environmental Studies, Center for Global Environmental Research, Japan (irina.melnikova.russia@gmail.com)
  • 3Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Commissariat à l’énergie atomique et aux énergies alternatives (CEA CNRS UVSQ), Gif-sur-Yvette, France
  • 4International Institute for Applied Systems Analysis (IIASA), Austria
  • 5Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan

There is a substantial gap between the current emissions of greenhouse gases and levels required for achieving the 2 and 1.5 °C temperature targets of the Paris Agreement. Understanding the implications of a temperature overshoot is thus an increasingly relevant research topic. We carry out a study as part of the “Achieving the Paris Agreement Temperature Targets after Overshoot (PRATO)” project of the MOPGA programme on the 2 °C overshoot of the Paris Agreement temperature target. We explore the carbon cycle feedbacks over land and ocean in the SSP5-3.4-OS overshoot scenario by using an ensemble of Coupled Model Intercomparison Project 6 Earth system models. Models show that after the CO2 concentration and air temperature peaks, land and ocean are decreasing carbon sinks from the 2040s and become sources for a limited time in the 22nd century. The decrease in the carbon uptake precedes the CO2 concentration peak. The early peak of the ocean uptake stems from its dependency on the atmospheric CO2 growth rate. The early peak of the land uptake occurs due to a larger increase in ecosystem respiration than the increase in gross primary production, as well as due to a concomitant increase in land-use change emissions primarily attributed to the wide implementation of biofuel croplands. The carbon cycle feedback parameters amplify after the CO2 concentration and temperature peaks, so that land and ocean absorb more carbon per unit change in the atmospheric CO2 change (stronger negative feedback) and lose more carbon per unit temperature change (stronger positive feedback) compared to if the feedbacks stayed unchanged. The increased negative CO2 feedback outperforms the increased positive climate feedback. This feature should be investigated under other scenarios and reflected in simple climate models.

How to cite: Melnikova, I., Boucher, O., Cadule, P., Ciais, P., Gasser, T., Quilcaille, Y., Shiogama, H., Tachiiri, K., Yokohata, T., and Tanaka, K.: Carbon cycle response to temperature overshoot beyond 2 °C – an analysis of CMIP6 models, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-819, https://doi.org/10.5194/egusphere-egu21-819, 2021.

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