Goethe-University Frankfurt, Altenhoeferallee 1, 60438, Frankfurt am Main, Germany.
Biodiversity and Climate Research Centre (BIK-F), Senckenberganlage 25, 60325 Frankfurt am Main, Germany.
Sci Rep. 2017 Jan 5;7:39842. doi: 10.1038/srep39842.
Tectonically induced changes in oceanic seaways had profound effects on global and regional climate during the Late Neogene. The constriction of the Central American Seaway reached a critical threshold during the early Pliocene ~4.8-4 million years (Ma) ago. Model simulations indicate the strengthening of the Atlantic Meridional Overturning Circulation (AMOC) with a signature warming response in the Northern Hemisphere and cooling in the Southern Hemisphere. Subsequently, between ~4-3 Ma, the constriction of the Indonesian Seaway impacted regional climate and might have accelerated the Northern Hemisphere Glaciation. We here present Pliocene Atlantic interhemispheric sea surface temperature and salinity gradients (deduced from foraminiferal Mg/Ca and stable oxygen isotopes, δO) in combination with a recently published benthic stable carbon isotope (δC) record from the southernmost extent of North Atlantic Deep Water to reconstruct gateway-related changes in the AMOC mode. After an early reduction of the AMOC at ~5.3 Ma, we show in agreement with model simulations of the impacts of Central American Seaway closure a strengthened AMOC with a global climate signature. During ~3.8-3 Ma, we suggest a weakening of the AMOC in line with the global cooling trend, with possible contributions from the constriction of the Indonesian Seaway.
构造引起的海洋海峡变化在晚新生代对全球和区域气候产生了深远影响。中美洲海峡的收缩在大约 480 万至 400 万年前的上新世早期达到了一个关键的阈值。模型模拟表明，北大西洋经向翻转环流（AMOC）的加强导致北半球变暖，南半球变冷。随后，在大约 400 万至 300 万年前，印度尼西亚海峡的收缩影响了区域气候，并可能加速了北半球的冰川作用。我们在这里提出上新世大西洋半球间海表温度和盐度梯度（由有孔虫镁/钙和稳定氧同位素 δO 推断得出），并结合最近发表的北大西洋深层水最南端的底栖稳定碳同位素（δC）记录，以重建与 AMOC 模式相关的海峡变化。在大约 530 万年前 AMOC 早期减少之后，我们的研究结果与中美洲海峡关闭对 AMOC 影响的模型模拟一致，表明 AMOC 得到了加强，具有全球气候特征。在大约 380 万至 300 万年前，我们认为 AMOC 减弱，与全球变冷趋势一致，可能与印度尼西亚海峡的收缩有关。
