title: Key knowledge and data gaps in modelling the influence of CO2concentration on the terrestrial carbon sink.
abstract: Primary productivity of terrestrial vegetation is expected to increase under the influence of increasing atmospheric carbon dioxide concentrations ([CO2]). Depending on the fate of such additionally fixed carbon, this could lead to an increase in terrestrial carbon storage, and thus a net terrestrial sink of atmospheric carbon. Such a mechanism is generally believed to be the primary global driver behind the observed large net uptake of anthropogenic CO2emissions by the biosphere. Mechanisms driving CO2uptake in the Terrestrial Biosphere Models (TBMs) used to attribute and project terrestrial carbon sinks, including that from increased [CO2], remain in large parts unchanged since those models were conceived two decades ago. However, there exists a large body of new data and understanding providing an opportunity to update these models, and directing towards important topics for further research. In this review we highlight recent developments in understanding of the effects of elevated [CO2] on photosynthesis, and in particular on the fate of additionally fixed carbon within the plant with its implications for carbon turnover rates, on the regulation of photosynthesis in response to environmental limitations on in-plant carbon sinks, and on emergent ecosystem responses. We recommend possible avenues for model improvement and identify requirements for better data on core processes relevant to the understanding and modelling of the effect of increasing [CO2] on the global terrestrial carbon sink.
authors.affiliation: School of Geography, Earth & Environmental Sciences and Birmingham Institute of Forest Research, University of Birmingham, Birmingham, B15 2TT, United Kingdom; Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany. Electronic address: t.a.m.pugh@bham.ac.uk.
authors.forename: T A M
authors.initials: TAM
authors.lastname: Pugh
authors.affiliation: Potsdam Institute for Climate Impact Research, Potsdam, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Müller
authors.affiliation: Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research-Atmospheric Environmental Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Arneth
authors.affiliation: CSIRO Oceans and Atmosphere, P.O. Box 3023, Canberra ACT 2601, Australia.
authors.forename: V
authors.initials: V
authors.lastname: Haverd
authors.affiliation: Department of Physical Geography and Ecosystem Science, Lund University, SE-223 62 Lund, Sweden.
authors.forename: B
authors.initials: B
authors.lastname: Smith
mesh_terms: D002245:Carbon Dioxide / Q000378:metabolism*; D057965:Carbon Sequestration; D017753:Ecosystem; D008962:Models, Theoretical; D010788:Photosynthesis; D013223:Statistics as Topic
chemical_list: D002245:Carbon Dioxide