Branched glycerol dialkyl glycerol tetraethers (brGDGTs) are bacterial cell membrane lipids that, when preserved in sedimentary archives, can be used to infer continental paleotemperatures. Although commonly used global calibrations capture a relationship between the distribution of brGDGTs and temperature, they underestimate temperatures for tropical regions as much as ~16°C. Furthermore, some global calibrations reach saturation at around 24–25°C, and, in general, they have root‐mean‐squared errors (RMSEs ≈ ~4°C) that are too large for them to resolve small variations in paleoclimate variability in tropical regions. We present an in situ regional calibration of soil brGDGTs along altitudinal transects on both flanks of the Eastern Cordillera of Colombia in the northern tropical Andes that spans ~3,200 m in elevation and 17°C and 19°C in mean annual soil and air temperatures, respectively. These new soil and air regional calibrations yield RMSEs of 1.5°C and 1.9°C, respectively. When combined with existing data from elsewhere in the tropics, the integrated data (n  = 175) not only fit a linear calibration with a RMSE of 2.7°C but also fit a nonlinear calibration with a RMSE of 2.2°C. These calibrations allow for a more precise and reliable reconstruction of past temperatures in the tropics than global calibrations.

中文翻译：

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使用支链GDGT对哥伦比亚热带安第斯山脉进行土壤和气温校准：迈向全热带校准

支链甘油二烷基甘油四醚（brGDGTs）是细菌细胞膜脂质，当保存在沉积档案中时，可用于推断大陆古温度。尽管常用的全球校准方法可以捕获brGDGT的分布与温度之间的关系，但它们低估了热带地区的温度，最高可达〜16°C。此外，某些全球校准在24–25°C左右达到饱和，并且通常具有均方根误差（RMSE≈〜4°C），对于他们来说，它们无法解决古气候变化中的小变化。热带地区。我们在北部热带安第斯山脉的哥伦比亚东部山脉两侧的海拔两侧，沿垂直样带对土壤brGDGTs进行了原位区域校准，海拔分别为200 m，平均每年土壤和气温分别为17°C和19°C。这些新的土壤和空气区域校准分别产生1.5°C和1.9°C的均方根误差（RMSE）。与热带地区其他地方的现有数据结合后，综合数据（n  = 175）不仅适用于2.7°C的RMSE的线性校准，而且适用于2.2°C的RMSE的非线性校准。与全球校准相比，这些校准可以更精确，更可靠地重建热带地区过去的温度。