Land contribution to natural CO₂ variability on time scales of centuries

Abstract

[1] The present paper addresses the origin of natural variability arising internally from the climate system of the global carbon cycle at centennial time scales. The investigation is based on the Max Planck Institute for Meteorology, Coupled Model Intercomparison Project Phase 5 (MPI-MCMIP5) preindustrial control simulations with the MPI Earth System Model in low resolution (MPI-ESM-LR) supplemented by additional simulations conducted for further analysis. The simulations show a distinct low-frequency component in the global terrestrial carbon content that induces atmospheric CO 2 variations on centennial time scales of up to 3 ppm. The main drivers for these variations are low-frequency fluctuations in net primary production (NPP) of the land biosphere. The signal arises from small regions scattered across the whole globe with a pronounced source in North America. The main reason for the global NPP fluctuations is found in climatic changes leading to longterm variations in leaf area index, which largely determines the strength of photosynthetic carbon assimilation. The underlying climatic changes encompass several spatial diverse climatic alterations. For the particular case of North America, the carbon storage changes are (besides NPP) also dependent on soil respiration. This second mechanism is strongly connected to low-frequency variations in incoming shortwave radiation at the surface.Citation: Schneck, R., C. H. Reick, and T. Raddatz (2013), Land contribution to natural CO 2 variability on time scales of centuries,

Constraining a land-surface model with multiple observations by application of the MPI-Carbon Cycle Data Assimilation System V1.0

“…Partly driven by the reduction of GPP, the NPP was also significantly reduced to 46 PgC yr −1 in the JOINT experiment. While such a value is lower than the commonly accepted reference value of 60 PgC yr −1 , it is still compatible with the range of available estimates for NPP of 44-66 PgC yr −1 (Cramer et al, 1999;Saugier and Roy, 2001). The latitudinal distribution of GPP in comparison to an empirical estimate based on satellite data and field measurements (Jung et al, 2011) shows that the global reduction of GPP led to a better agreement of GPP in the northern extra-tropics between 30 and 60 • N, but to a lower GPP in the tropical rain forests (Fig.…”

“…The model that is optimised within the MPI-CCDAS is the JSBACH land-surface model (Raddatz et al, 2007;Brovkin et al, 2009;Reick et al, 2013;Schneck et al, 2013;Dalmonech and Zaehle, 2013). The model considers 10 plant functional types (PFTs: see Table 1).…”

Reconstructions of biomass burning from sediment-charcoal records to improve data–model comparisons

“…As an example, we present here a global map of simulated area burned using the CLIMBA model (Brücher et al, 2014), overlaid with gridded composite charcoal anomalies from the GCD. CLIMBA consists of the EMIC CLIMBER-2 (CLIMate and BiosphERe; Petoukhov et al, 2000;Ganopolski et al, 2001) and JS-BACH (Raddatz et al, 2007;Brovkin et al, 2009;Schneck et al, 2013), which is the land component of the Max Planck Institute Earth System Model (MPI-ESM, Giorgetta et al, 2013). Simulated area burned throughout the Holocene was treated analogously to GCD data to produce a gridded map of area-burned anomalies at 6000 BP relative to present (i.e., 6000 BP z scores minus 0 BP z scores).…”

The Land Use Model Intercomparison Project (LUMIP) contribution to CMIP6: rationale and experimental design

“…Land-cover change usually goes hand in hand with land-use change, but the opposite is not true. Land-cover change can also be driven by natural processes such as a change in the biogeographic vegetation distribution due to climate shifts or natural disturbance (DaviesBarnard et al, 2015;Schneck et al, 2013). For the purposes of LUMIP, the term "LULCC" includes anthropogenically driven land-cover change only.…”