Earth system modelling provides invaluable insights into past climates and environments. The reconstruction of paleo-environments can be used to inform paleoecology by coupling marine ecosystems/biogeochemical models. However, the current generation of marine biogeochemical models has limited plankton functional types calibrated with modern species. To address this, we present a trait-based plankton dynamic model in an Earth system model of intermediate complexity (cGENIE) and its application in the Last Glacial Maximum (LGM).  We reconstructed 19 marine plankton groups, including four planktic foraminifera groups in the LGM, pre-industrial state, and 2100. The results show that although symbiont-barren foraminifera showed limited niche changes, the optimal temperature for symbiont-bearing spinose foraminifera has increased since the LGM, showing their adaptive ability to deglacial warming. Projecting the same model into the future shows a more limited change due to decreasing food supply, indicating the vulnerability of marine plankton under modern climate change. Our results are supported by fossil records and modern foraminifera data compilations, demonstrating the power of a trait-based model in palaeoceanography and micropaleontology.

earth system modeling,marine plankton,Marine Ecosystem Modelling