Dust impact on marine biota and atmospheric CO 2 during glacial periods

• Published in: Paleoceanography
• Main Authors: Bopp, Laurent, Kohfeld, Karen, Le Quéré, Corinne, Aumont, Olivier
• Other Authors: Max-Planck-Institut für Biogeochemie (MPI-BGC), Laboratoire d'océanographie dynamique et de climatologie (LODYC), Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2003
• Subjects: Last Glacial Maximum; pCO2; ocean; biogeochemistry; dust; iron; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Pacific; Southern Ocean; Sea ice
• Online Access: https://hal.science/hal-03131780; https://hal.science/hal-03131780/document; https://hal.science/hal-03131780/file/2002PA000810.pdf; https://doi.org/10.1029/2002PA000810

International audience We assess the impact of high dust deposition rates on marine biota and atmospheric CO 2 using a state-ofthe-art ocean biogeochemistry model and observations. Our model includes an explicit representation of two groups of phytoplankton and colimitation by iron, silicate, and phosphate. When high dust deposition rates from the Last Glacial Maximum (LGM) are used as input, our model shows an increase in the relative abundance of diatoms in today's iron-limited regions, causing a global increase in export production by 6% and an atmospheric CO 2 drawdown of 15 ppm. When the combined effects of changes in dust, temperature, ice cover, and circulation are included, the model reproduces roughly our reconstruction of regional changes in export production during the LGM based on several paleoceanographic indicators. In particular, the model reproduces the latitudinal dipole in the Southern Ocean, driven in our simulations by the conjunction of dust, sea ice, and circulation changes. In the North Pacific the limited open ocean data suggest that we correctly simulate the eastwest gradient in the open ocean, but more data are needed to confirm this result. From our model-data comparison and from the timing of the dust record at Vostok, we argue that our model estimate of the role of dust is realistic and that the maximum impact of high dust deposition on atmospheric CO 2 must be <30 ppm.