Departamento de Geociencias, Universidad de los Andes, Bogotá, Colombia.
Department of Thematic Studies, Environmental Change, Linköping University, 58183, Linköping, Sweden.
Sci Rep. 2018 Mar 29;8(1):5386. doi: 10.1038/s41598-018-23606-w.
High-resolution paleoclimate data on stable isotopes in a stalagmite were coupled to glycerol dialkyl glycerol tetraethers (GDGTs). The Indian Summer Monsoon (ISM) transitioned from limited rainfall during the Last Glacial Maximum (LGM) to intense precipitation during early Holocene (22 to 6 ka). This was associated with changes in stalagmite growth, abundance of branched (br) and isoprenoid (iso) GDGTs, as well as δO, δC, Sr/Ca and GDGT-derived signals providing both temperature and moisture information. The reconstructed mean annual air temperature (MAAT) of the most modern stalagmite sample at ~19 °C, matches the surface and cave MAAT, but was ~4 °C lower during LGM. Warming at the end of LGM occurred before ISM strengthened and indicate 6 ka lag consistent with sea surface temperature records. The isotope records during the Younger Dryas show rapid progressions to dry conditions and weak monsoons, but these shifts are not coupled to TEX. Moreover, change to wetter and stronger ISM, along with warmer Holocene conditions are not continuous indicating a decoupling of local temperatures from ISM.
高分辨率古气候数据稳定同位素的石笋耦合甘油二烷基甘油四醚（GDGTs）。印度夏季风（ISM）从末次冰期最大值（LGM）期间的有限降雨转变为全新世早期（22 至 6 千年前）的强降水。这与石笋生长、支链（br）和异戊二烯（iso）GDGTs 的丰度变化以及δO、δC、Sr/Ca 和 GDGT 衍生信号有关，这些信号提供了温度和湿度信息。最现代石笋样本的重建年均气温（MAAT）约为 19°C，与地表和洞穴 MAAT 相匹配，但在 LGM 期间低约 4°C。LGM 末期的变暖发生在 ISM 增强之前，表明与海面温度记录一致的 6 ka 滞后。新仙女木时期的同位素记录显示出迅速向干燥条件和较弱季风的转变，但这些变化与 TEX 不相关。此外，向更湿润和更强的 ISM 以及更温暖的全新世条件的转变并不连续，表明当地温度与 ISM 脱钩。
