Large sensitivity in land carbon storage due to geographical and temporal variation in the thermal response of photosynthetic capacity
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Currently under an indefinite embargo pending publication by the publisher. 12 month embargo to be applied on publication
Plant temperature responses vary geographically reflecting thermally contrasting habitats and long-term species adaptations to their climate of origin. Plants can also acclimate to fast temporal changes in temperature regime to mitigate stress. Although plant photosynthetic responses are known to acclimate to temperature, many global models used to predict future vegetation and climate-carbon interactions do not include this process. • We quantify the global and regional impacts of biogeographic variability and thermal acclimation of temperature response of photosynthetic capacity on the terrestrial carbon cycle between 1860 and 2100 within a coupled climate- carbon cycle model, that emulates 22 global climate models. • Results indicate that inclusion of biogeographic variation in photosynthetic temperature response is most important for carbon uptake for the present-day and future, with increasing importance of thermal acclimation under future warming. Accounting for both effects narrows the range of predictions of the simulated global land carbon storage in 2100 across climate projections (29% and 43% globally and in the tropics, respectively). • Contrary to earlier studies, our results suggest that thermal acclimation of photosynthetic capacity makes tropical and temperate carbon less vulnerable to warming, but reduces the warming-induced carbon uptake in the boreal region under elevated CO2.
We acknowledge funding for short scientific visits during which part of this research was developed from the Royal Society UK International Exchanges Scheme, the European commission funded TERRABITES COST Action and the University of Exeter Outward mobility grant. LM acknowledges Natural Environment Research Council (NERC) standard grant ‘Can tropical Montane forest Acclimate to high temperature?’ (NE/R001928/1). C.H. acknowledges the CEH National Capability Budget. CH and LM acknowledge funding from NERC consortium grant ‘AMAZONICA’ (NE/F005806/1). This work used eddy covariance data acquired and shared by the FLUXNET community, including these networks: AmeriFlux, AfriFlux, AsiaFlux, CarboAfrica, CarboEuropeIP, CarboItaly, CarboMont, ChinaFlux, Fluxnet-Canada, GreenGrass, ICOS, KoFlux, LBA, NECC, OzFlux-TERN, TCOS-Siberia, and USCCC. The ERA-Interim reanalysis data are provided by ECMWF and processed by LSCE. The FLUXNET eddy covariance data processing and harmonization was carried out by the European Fluxes Database Cluster, AmeriFlux Management Project, and Fluxdata project of FLUXNET, with the support of CDIAC and ICOS Ecosystem Thematic Center, and the OzFlux, ChinaFlux and AsiaFlux offices.
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