Mineral Dust Coupled With Climate‐Carbon Cycle on Orbital Timescales Over the Past 4 Ma.

The behaviors between δ13Cbenthic and δ18Obenthic are anti‐phased after 6 Ma, and many mechanisms have been proposed to explain their behaviors. However, this question remains debated. Here, we reconstruct the interaction between mineral dust, global carbon cycle changes, and climate‐cryosphere system since 4 Ma. Our results suggest that Asian and/or global dust fluxes may have transported the signal of periodic Arctic ice sheet variability to the deep‐sea δ13Cbenthic record by mediating the strength of oceanic biological pumping. This can explain why δ13Cbenthic data show very similar orbital‐scale variability to δ18Obenthic changes controlled by Arctic ice sheet variability. A sharp increase in global dust fluxes after 1.6 Ma resulted in a significant weakening of the 405 kyr long eccentricity variance in δ13Cbenthic data. We propose that mineral dust may have been one of the most important factors controlling the anti‐phase relationship between δ13Cbenthic and δ18Obenthic over the past 6 million years. Plain Language Summary: Many mechanisms have been proposed to explain the phase relationship between benthic carbon isotopes (which record global carbon cycle changes) and benthic oxygen isotopes (which record ice volume/temperature) over the past few millions years, but these are still debated. In this study, a comparison of variations in the global ice volume/temperature, the global carbon cycle, and mineral dust released from continental interiors has been conducted. We find that variations in these parameters were very similar over the past 4 Ma at timescales linked to orbital climate forcing. We suggest that mineral dust transports periodic signals linked to orbital forcing of Arctic ice sheet variability to the deep‐sea record of Earth's carbon cycle by varying nutrient supply to the ocean, thus mediating carbon production/burial. Mineral dust may have played a role in controlling the anti‐phase relationship between deep sea oxygen isotopes and carbon isotopes around 6 Ma. Key Points: Mineral dust may facilitate the anti‐phase relationship between deep sea oxygen isotopes and carbon isotopes around 6 MaAsian and/or global dust transports the periodic signal stored in the Arctic ice sheet to deep sea carbon isotopeSharp increase of global dust fluxes after 1.6 Ma resulted in a weakening of the 405 kyr long eccentricity power in deep sea carbon isotopes [ABSTRACT FROM AUTHOR]