EGU21-16179, updated on 11 Jan 2022
https://doi.org/10.5194/egusphere-egu21-16179
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Increasing tropical water control on interannual CO2 growth rate over the past decades

Laibao Liu and Sonia Seneviratne
Laibao Liu and Sonia Seneviratne
  • ETH Zurich, Atmospheric and Climate Science, Switzerland

Terrestrial climate-carbon feedbacks are the leading-order uncertainties in climate projections, hindering the full assessment of climate mitigation scenarios. Since year-to-year variations of atmospheric carbon dioxide growth rate (CGR) are mostly driven by fluctuations of tropical land carbon fluxes, it provides a “natural experiment” to explore the climate drivers of terrestrial carbon cycle. Recently, direct observations of terrestrial water storage confirmed the tight coupling between the water and carbon cycles, in addition to the well-documented temperature effects. Here we show that the strength of this relationship between CGR and the interannual variability of tropical water has increased substantially from 1960 to 2018 and has even recently become stronger than CGR-temperature correlations. We find that this increment may be relevant to local drying trends in a warming climate and that above-ground carbon uptake might be a critical underlying ecological process. We also demonstrate that most state-of-the-art Earth System models and land surface models do not capture this increasing carbon-water coupling over time. Our results suggest that tropical water availability could increasingly dominates the interannual variability of the terrestrial carbon cycle in the future and that current models may not be able to capture this feature.

How to cite: Liu, L. and Seneviratne, S.: Increasing tropical water control on interannual CO2 growth rate over the past decades, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16179, https://doi.org/10.5194/egusphere-egu21-16179, 2021.

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