Elucidating the mechanisms of 400-kyr tropical hydroclimate variability during the Plio-Pleistocene

The control of the eccentricity on annual mean insolation is minimal. Yet, substantial variability in eccentricity timescales, especially the 400-kyr cycle, has been observed in tropical hydroclimate records. As suggested, this variability may have been significantly driven by long-term carbon cycle changes during the Plio-Pleistocene.

We present results from well-dated high-resolution paleoclimate proxies during the Plio-Pleistocene and an unprecedented transient climate simulation conducted with NCAR’s realistic Community Earth System Model version 1.2; the latter covers the climate history of the past 3Myr. The analyses of existing carbon isotope records (i.e., planktic and benthic δ¹³C) from deep marine sediment cores and other paleoclimatic (terrigenous dust flux) archives from the tropical ocean during the Pliocene and early Pleistocene (>1.5 Myr) reveal clear 400-kyr climate signals, suggesting eccentricity-paced changes in the long-term carbon cycle. Our model simulates 400-kyr variability in tropical hydroclimate. However, the climatic control on the robust feature of the carbon cycle (i.e., the 400-kyr oscillation) and its role and dynamics during the Plio-Pleistocene needs to be better understood. Our study investigates the interaction processes between various paleoenvironmental records and further focuses on different hypotheses following the antiphase relation of marine δ¹³C with the eccentricity cycle. First, we provide a combined perspective on the role of atmospheric circulation and, thus, dust in the dynamic of the carbon cycle and productivity. Also, come up with causes and links with the pacing of the carbon cycle and the ocean’s role. Second, assess the ecosystem response (vegetation) to changes in precipitation in connection with changes in atmospheric CO₂.