Suchergebnisse

This is the final version. Available on open access from AGU via the DOI in this record ; The dataset associated with this article is located in ORE at: https://doi.org/10.24378/exe.2883 ; Variability in climate exerts a strong influence on vegetation productivity (gross primary productivity; GPP), and therefore has a large impact on the land carbon sink. However, no direct observations of global GPP exist, and estimates rely on models that are constrained by observations at various spatial and temporal scales. Here, we assess the consistency in GPP from global products which extend for more than three decades; two observation-based approaches, the upscaling of FLUXNET site observations (FLUXCOM) and a remote sensing derived light-use efficiency model (RS-LUE), and from a suite of terrestrial biosphere models (TRENDYv6). At local scales, we find high correlations in annual GPP amongst the products, with exceptions in tropical and high northern latitudes. On longer timescales, the products agree on the direction of trends over 58% of the land, with large increases across northern latitudes driven by warming trends. Further, tropical regions exhibit the largest interannual variability in GPP, with both rainforests and savannas contributing substantially. Variability in savanna GPP is likely predominantly driven by water availability, although temperature could play a role via soil moisture – atmosphere feedbacks. There is, however, no consensus on the magnitude and driver of variability of tropical forests, which suggest uncertainties in process representations and underlying observations remain. These results emphasise the need for more direct long-term observations of GPP along with an extension of in-situ networks in underrepresented regions (e.g. tropical forests). Such capabilities would support efforts to better validate relevant processes in models, to more accurately estimate GPP. ; European Union ; European Space Agency ; Natural Environment Research Council (NERC) ; NASA