Seasonal variations of atmospheric CO2 concentration under climate change

Using the Earth system model MPI-ESM-1.2, we ran a large ensemble of CO₂ emission-driven simulations enabling the interactive carbon cycle. In such simulations, CO₂ emissions are prescribed and the atmospheric CO₂ is computed prognostically. Thereby, the strength of the ocean and land sinks of carbon, represented by the ocean biogeochemistry model HAMOCC and the land vegetation model JSBACH, respectively, modulate variations of atmospheric CO₂. This approach represents the global carbon cycle with greater realism in comparison to simulations forced by prescribed CO₂ concentrations.

In this visualization, changes in the color indicate the simulated increase in the global atmospheric CO₂ concentrations due to rising emissions for the historical past (1960-2014) and for the four Shared Socio-economic Pathways scenarios SSP126, SSP245, SSP370 and SSP585 (2015-2100). By mapping the surface atmospheric CO₂ concentration with color and its relative seasonal variation with height, the visualization also demonstrates regional changes in the seasonal cycle that depend on the strength of the forcing – note the peaks visible towards the end of the visualization for SSP370 and SSP585. Atmospheric CO₂ concentration evolves differently following the pace of anthropogenic emissions in different scenarios. It further varies throughout the year through photosynthesis and respiration by land vegetation and marine phytoplankton.

These simulations allow us to address a number of questions on the role of different climate policies on carbon feedbacks.

Simulation: Hongmei Li, Tatiana Ilyina, MPI for Meteorology

Visualization: Michael Böttinger, DKRZ

Text: Tatiana Ilyina & Michael Böttinger

Literature: Li, H., T. Ilyina, T. Loughran, J. Pongratz: Reconstructions and predictions of the global carbon cycle with an emission-driven Earth System Model. Geophysical Research Letters, submitted.