美国哥伦比亚大学
据介绍，目前温室气体（GHG）导致地中海降雨量下降的机制仍存在争议。为了更好地理解当前和预测的干旱，课题组研究了晚第四纪东地中海（EM）黎凡特地区延长的干旱间隔，这表明在过去220万年的死海沉积物岩心中有大量的盐沉积。
这些干旱事件发生在间冰期，当时地球在北方秋季处于太阳近日点，以及在冰期—间冰期过渡期间，与冰盖融化有关。第四纪晚期实际日照变化强迫的气候模型表明，当地球在北方秋季最接近太阳时，北大西洋冬季纬向表面温度梯度加剧。因此，上空的中纬度北大西洋急流和温带风暴路径向极地移动，同时副热带的海平面气压上升。这些变化使地中海风暴路径减弱，整个流域的降雨量减少。
在冰期-间冰期过渡期间，来自大陆冰原的融水迫使北大西洋亚极区突然变冷。这也加强了纬向表面温度梯度，可能与地中海类似的大气响应和干旱有关。这一古气候情景与对应于当前和预估的EM温室气体干燥的气候变化有很强的相似性。因此，死海的晚第四纪古水文信息表明了北大西洋中心对外部作用力的重要响应，这导致了地中海的干燥，并与现代有关。
附：英文原文
Title: Paleo aridity in the Levant driven by a strong North Atlantic latitudinal surface temperature gradient and present-day relevance
Author: Kushnir, Yochanan, Stein, Mordechai, Biasutti, Michela, Kiro, Yael, Goldsmith, Yonaton, Goldstein, Steven L.
Issue&Volume: 2024-11-11
Abstract: The mechanisms underlying the current greenhouse gas (GHG) forced decline in Mediterranean rainfall remain a matter of debate. To inform our understanding of the current and projected drying, we examined extended arid intervals in the late Quaternary, Eastern Mediterranean (EM) Levant indicated by substantial salt deposits in a Dead Sea sediment core covering the past 220 kyr. These arid events occurred during interglacials, when the Earth was at perihelion to the sun in boreal fall and during glacial–interglacial transitions, associated with icesheet melting. Climate models forced with realistic late Quaternary insolation variations show that when the Earth is closest to the Sun in boreal fall, the North Atlantic latitudinal surface temperature gradient in the winter intensifies. In response, the overlying midlatitude North Atlantic jet stream and the extratropical storm track move poleward while sea-level pressure rises in the subtropics. These changes bring about a weakening of the Mediterranean storm track and a decline in rainfall over the entire basin. During glacial–interglacial transitions, meltwater from continental icesheets forced abrupt subpolar North Atlantic cooling. This also strengthened the latitudinal surface temperature gradient, likely causing similar atmospheric response and aridity in the Mediterranean. There is a strong resemblance between this paleoclimate scenario and the climatic changes corresponding to the present and projected GHG drying of the EM. Hence, the late Quaternary palaeohydrology of the Dead Sea indicates an important North Atlantic centered response to external forcing, which leads to Mediterranean drying and is relevant in the present.
DOI: 10.1073/pnas.2407166121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2407166121