4C aims to advance our understanding of the carbon cycle over the historical period, as an essential prerequisite of reliable near-term predictions and long-term projections. This will be achieved by developing and making use of novel observations and data products to constrain the land and ocean carbon fluxes and their drivers, combined with forced land and ocean carbon cycle model simulations over the historical period (1900-2020), and fully coupled ESM simulations over the last 30 years to improve our understanding of underlying processes, particularly focusing on the response of carbon fluxes to increase in atmospheric CO2, seasonal to decadal climate variability, and climatic extremes.

4C will provide new observational constraints, improved data-based products and historical model simulations to support the model evaluation against these observations. This project will also improve the key process representations and the attribution of key drivers controlling the evolution and variability of the carbon sinks.

By the end of the project, we have the ambition to improve our modelling of the processes regulating the land and ocean carbon sinks such that the combined carbon budget imbalance is reduced by a factor of two (mean absolute deviation of the BIM decreasing from 0.7 GtCyr-1 to 0.35 GtCyr-1).

Research line 1

Schematic representation of the overall perturbation of the global carbon cycle caused by anthropogenic activities, averaged globally for the decade of 2009-2018. Adapted from: Friedlingstein, P., et al. Global Carbon Budget 2019, Earth Syst. Sci. Data, 11, 1783-1838, 2019. doi: 10.5194/essd-11-1783-2019

Team members

Anthony Jude De-Gol
University of East Anglia (UEA)
Bettina Gier
University of Bremen
Corinne Le Quéré
University of East Anglia (UEA)
Etienne Tourigny
Barcelona Supercomputing Center (BSC)
Fortunat Joos
University of Bern
Glen Peters
Center for International Climate Research (CICERO)
Jens Müller
ETH Zurich
Laurent Bopp
École normale supérieure (ENS)
Leo de Sousa-Webb
University of Exeter
Luke Gregor
ETH Zurich
Lydia Keppler
Max Planck Institute (MPI)
Michael Schlund
German Aerospace Center (DLR)
Maximilian Reuter
University of Bremen
Michael Buchwitz
University of Bremen
Michael O'Sullivan
University of Exeter
Myles Allen
University of Oxford
Nicolas Gruber
ETH Zurich
Nicolas Mayot
University of East Anglia (UEA)
Peter Landschützer
Max Planck Institute (MPI)
Pierre Friedlingstein
University of Exeter
Raffaele Bernardello
Barcelona Supercomputing Center (BSC)
Robbie Andrew
Center for International Climate Research (CICERO)
Sabrina Zechlau
German Aerospace Center (DLR)
Sebastian Lienert
University of Bern
Sönke Zaehle
Max Planck Institute (MPI)
Thomas Frölicher
University of Bern
Valentina Sicardi
Barcelona Supercomputing Center (BSC)
Veronika Eyring
German Aerospace Center (DLR)
Victor Brovkin
Max Planck Institute (MPI)