International Journal of Marine Science, 2024, Vol.14, No.2, 51-56 http://www.aquapublisher.com/index.php/ijms 53 Figure 3 presents the development of the ACC over the past 1.5 million years. The black curve represents the accumulation of oxygen isotopes from benthic foraminifera, revealing changes in ocean temperature and ice volume. The blue curve shows the atmospheric CO2 content recorded in Antarctic ice cores, with both collectively presenting the history of Earth's climate changes. The red curve represents the relative ACC strength changes at the entrance of the Drake Passage, core PS97/93, while other colored curves indicate the relative ACC strength changes at sites U1540, U1541, and core PS75/76. These data show that during the early Mid-Pleistocene Transition (MPT), the ACC experienced a noticeable increase in strength. Lastly, the black, blue, and red bar graphs reflect changes in the content of biogenic opal (Opal) in sediments at different locations, providing paleobiogeographic evidence of past changes in the ACC. The comparison of these multiple records reveals the complex connection between the ACC and global climate transitions. Figure 3 ACC development over the past 1500 kyr Figure 4 details the development history of the ACC since the Pliocene. The black line represents the long-term record of oxygen isotopes from benthic foraminifera, reflecting ocean temperature changes over the past several million years. The model data, combined with the ice sheet expansion reconstruction results from ANDRILL (AND-1B), depict the ice dynamics in the Ross Sea. The red and blue curves represent the measured changes in ACC relative strength at sites U1540 and U1541, while the black smoothed line reveals the trend of ACC strength over a million-year scale. Additionally, the figure shows the magnetic susceptibility record of the East Asian monsoon intensity, changes in the North Pacific carbonate accumulation rate, and variations in the ratio of biogenic opal to CaCO3 at sites U1540 and U1541. These are important indicators for understanding the historical strength variations of the ACC. Figure 4 provides valuable historical evidence for studying the global climate system and the role of the ACC within it.
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