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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2019-428
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-428
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 04 Nov 2019

Submitted as: research article | 04 Nov 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Recent changes in the dominant environmental controls of net biome productivity

Barbara Marcolla1, Mirco Migliavacca2, Christian Rödenbeck2, and Alessandro Cescatti3 Barbara Marcolla et al.
  • 1Sustainable Agro-ecosystems and Bioresources Department, IASMA Research and Innovation Centre, Fondazione Edmund Mach Via E. Mach 1, 38010 San Michele all'Adige, (TN), Italy
  • 2Max Planck Institute for Biogeochemistry, Jena, 07745, Germany
  • 3European Commission, Joint Research Centre (JRC), Ispra, Italy

Abstract. In the last decades terrestrial ecosystems have reabsorbed on average more than one quarter of anthropogenic emissions (Le Quéré et al., 2018). However, this large carbon sink is modulated by climate and is therefore highly variable in time and space. The magnitude and temporal changes of the sensitivity of terrestrial CO2 fluxes to climate drivers are key factors to determine future atmospheric CO2 concentration and climate trajectories. In the literature there is so far a strong focus on the climatic controls of inter-annual variability, while less is known about the key drivers of the sub-annual variability of the fluxes. This latter temporal scale is relevant to assess which climatic drivers dominate the seasonality of the fluxes and to understand which factors limit the net ecosystem CO2 exchange. Here, we investigated the global sensitivity of terrestrial CO2 fluxes to three key climate drivers (i.e. global radiation, temperature and soil water content) from weekly to seasonal temporal scales, in order to explore the short-term interdependence between climate and the terrestrial carbon budget. We observed that the CO2 exchange over most of the land surface is controlled by temperature during the carbon uptake period, while radiation is the most widespread dominant climate driver during the carbon release period. As expected, soil water content plays a key role in arid regions of the southern hemisphere. Looking at the decadal trend of these sensitivities we observed that the importance of radiation as a driver is increasing over time, while we observed a decrease in sensitivity to temperature in Eurasia. Overall, we show that the temporal variation of the fluxes due to a specific driver is dominated by the temporal changes in ecosystem sensitivity rather than to the temporal variability of the driver itself. Ultimately this analysis shows that the response of the ecosystem to climate drivers is significantly changing both in space and in time, with potential repercussion on the future terrestrial CO2 sink and therefore on the role that land may play in climate mitigation.

Barbara Marcolla et al.
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Status: open (until 16 Dec 2019)
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Barbara Marcolla et al.
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Short summary
This work investigates the sensitivity of terrestrial CO2 fluxes to climate drivers. We observed that CO2 flux is mostly controlled by temperature during the growing season and by radiation off season. We also observed that radiation importance is increasing over time while sensitivity to temperature is decreasing in Eurasia. Ultimately this analysis shows that ecosystem response to climate is changing with potential repercussion on future terrestrial sink and on land role in climate mitigation.
This work investigates the sensitivity of terrestrial CO2 fluxes to climate drivers. We observed...
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