Travis-Taylor Leah, Medina-Elizalde Martín, Karmalkar Ambarish V, Polanco-Martinez Josué, Serrato Marks Gabriela, Burns Stephen, Lases-Hernández Fernanda, McGee David
Department of Earth, Geographic, and Climate Sciences, UMass Amherst, Amherst, MA, USA.
Department of Geosciences, University of Rhode Island, Kingston, RI, USA.
Sci Rep. 2023 Sep 1;13(1):14356. doi: 10.1038/s41598-023-40108-6.
We reconstructed hydroclimate variability in the Yucatán Peninsula (YP) based on stalagmite oxygen and carbon isotope records from a well-studied cave system located in the northeastern YP, a region strongly influenced by Caribbean climate dynamics. The new stalagmite isotopic records span the time interval between 43 and 26.6 ka BP, extending a previously published record from the same cave system covering the interval between 26.5 and 23.2 ka BP. Stalagmite stable isotope records show dominant decadal and multidecadal variability, and weaker variability on millennial timescales. These records suggest significant precipitation declines in the broader Caribbean region during Heinrich events 4 and 3 of ice-rafted discharge into the North Atlantic, in agreement with the antiphase pattern of precipitation variability across the equator suggested by previous studies. On millennial timescales, the stalagmite isotope records do not show the distinctive saw-tooth pattern of climate variability observed in Greenland during Dansgaard-Oeschger (DO) events, but a pattern similar to North Atlantic sea surface temperature (SST) variability. We propose that shifts in the mean position of the Intertropical Convergence Zone (ITCZ), per se, are not the dominant driver of last glacial hydroclimate variability in the YP on millennial timescales but instead that North Atlantic SSTs played a dominant role. Our results support a negative climate feedback mechanism whereby large low latitude precipitation deficits resulting from AMOC slowdown would lead to elevated salinity in the Caribbean and ultimately help reactivate AMOC and Caribbean precipitation. However, because of the unique drivers of future climate in the region, predicted twenty-first century YP precipitation reductions are unlikely to be modulated by this negative feedback mechanism.
我们基于尤卡坦半岛（YP）东北部一个经过充分研究的洞穴系统中的石笋氧同位素和碳同位素记录，重建了该半岛的水文气候变化。该地区受加勒比海气候动态的强烈影响。新的石笋同位素记录跨越了43至26.6 ka BP的时间间隔，扩展了先前发表的同一洞穴系统在26.5至23.2 ka BP之间的记录。石笋稳定同位素记录显示出主要的年代际和多年代际变化，以及在千年时间尺度上较弱的变化。这些记录表明，在北大西洋冰筏排放的海因里希事件4和3期间，更广泛的加勒比地区降水量显著下降；这与先前研究提出的赤道两侧降水变化的反相位模式一致。在千年时间尺度上，石笋同位素记录没有显示出在丹斯加德-厄施格尔（DO）事件期间格陵兰岛观测到的独特锯齿状气候变率模式，而是与北大西洋海表面温度（SST）变率相似的模式。我们认为，热带辐合带（ITCZ）平均位置的变化本身并不是末次冰期YP千年时间尺度上海文气候变化的主要驱动因素，而是北大西洋海表面温度发挥了主导作用。我们的结果支持一种负气候反馈机制，即大西洋经向翻转环流（AMOC）放缓导致的低纬度地区大量降水赤字会导致加勒比海盐度升高，并最终有助于重新激活AMOC和加勒比地区降水。然而，由于该地区未来气候的独特驱动因素，预计21世纪YP降水量的减少不太可能受这种负反馈机制的调节。
