Increasing Ecosystem Fluxes Observed from Eddy Covariance and Solar-Induced Fluorescence Data

Ecosystems modulate Earth’s climate through the exchange of carbon and water fluxes. However, long-term trends in these terrestrial fluxes remain unclear due to the lack of continuous measurements on the global scale. This study combined flux data from 197 eddy covariance sites with satellite-retrieved solar-induced chlorophyll fluorescence (SIF) to investigate spatiotemporal variations in gross primary productivity (GPP), evapotranspiration (ET), and their coupling via water use efficiency (WUE) from 2001 to 2020. We developed six global GPP and ET products at 0.05° spatial and 8-day temporal resolution, using two machine learning models and three SIF products, which integrate vegetation physiological parameters with data-driven approaches. These datasets provided mean estimates of 128 ± 2.3 Pg C yr−1 for GPP, 522 ± 58.2 mm yr−1 for ET, and 1.8 ± 0.21 g C kg−1 H2O yr−1 for WUE, with upward trends of 0.22 ± 0.04 Pg C yr−2 in GPP, 0.64 ± 0.14 mm yr−2 in ET, and 0.0019 ± 0.0005 g C kg−1 H2O yr−2 in WUE over the past two decades. These high-resolution datasets are valuable for exploring terrestrial carbon and water responses to climate change, as well as for benchmarking terrestrial biosphere models.