Lucia Giuseppe, Zanchettin Davide, Winter Amos, Cheng Hai, Rubino Angelo, Vásquez Osmín J, Bernal Juan Pablo, Cu-Xi Mario, Lachniet Matthew S
Department of Geoscience, University of Nevada Las Vegas, Las Vegas, NV, USA.
Department of Environmental Sciences, Informatics and Statistics, University Ca' Foscari of Venice, Mestre, Italy.
Nat Commun. 2024 Dec 4;15(1):10586. doi: 10.1038/s41467-024-54856-0.
Tropical hydroclimate in monsoonal regions has been largely understood according to the orbital monsoon hypothesis, in which rainfall exhibits strong covariation with local summer insolation on precessional (~21,000 years) time scales, as exemplified in the Asian and South American monsoon stalagmite records. However, paleo-rainfall variations in some tropical regions are poorly explained by the orbital hypothesis, suggesting alternative forcing mechanisms of regional monsoon changes. Here, we show a 140,000-year record of Central American rainfall from oxygen-isotope (δO) time series of precisely dated stalagmites which reveals two dominant thermally-controlled monsoon regimes in which the Atlantic Ocean thermal state linked to the meridional overturning circulation (AMOC) is the primary driver, and local orbital summer insolation control is limited. Our reconstruction, supported by isotope-enabled climate model simulations, pinpoints the potential impacts of future AMOC weakening on the Central American and Caribbean climate.
季风区的热带水文气候在很大程度上已根据轨道季风假说得到理解，在该假说中，降雨在岁差（约21,000年）时间尺度上与当地夏季日照呈现强烈的协变关系，亚洲和南美季风石笋记录就是例证。然而，轨道假说对一些热带地区的古降雨变化解释不佳，这表明区域季风变化存在其他强迫机制。在此，我们通过精确测年的石笋的氧同位素（δO）时间序列展示了一条长达14万年的中美洲降雨记录，该记录揭示了两种主要的受温度控制的季风模式，其中与经向翻转环流（AMOC）相关的大西洋热状态是主要驱动因素，而当地轨道夏季日照控制作用有限。我们的重建得到了启用同位素的气候模型模拟的支持，确定了未来AMOC减弱对中美洲和加勒比地区气候的潜在影响。
