ENSO-Induced GPP Extremes Simulated by the CMIP6 Models

El Niño-Southern Oscillation (ENSO) is one of the major modes of climate variability and normally has a significant global impact on weather, climate and terrestrial and marine biogeochemical cycles. Extremes of the terrestrial carbon cycle, i.e., of Gross Primary Production (GPP), are generally caused by climatic extremes including drought, flood, heat and cold waves. Accurately simulating the terrestrial biogeochemistry responses to the extremes caused by climate variability like ENSO is still a challenge for Earth System Models (ESMs). The Coupled Model Intercomparison Project (CMIP) provides a systematic way to study those responses simulated by state-of-the-art models all over the world. We evaluated the results of AMIP and HISTORICAL experiments from CMIP6 and found that the ENSO-induced GPP extremes varied greatly across CMIP6 models, especially for the HISTORICAL experiment, though the simulated GPP mean states are very similar. The AMIP results with prescribed Sea Surface Temperature (SST) generally simulate the ENSO effects on climate and terrestrial ecosystem reasonably well compared with the HISTORICAL experiment.