Hydrogen isotope ratios of sedimentary leaf waxes (δ²H_Wax values) are increasingly used to reconstruct past hydroclimate. Here, we add δ²H_Wax values from 19 lakes and four swamps on 15 tropical Pacific islands to an updated global compilation of published data from surface sediments and soils. Globally, there is a strong positive linear correlation between δ²H values of mean annual precipitation (δ²H_P values) and the leaf waxes n‐C₂₉‐alkane (R² = 0.74, n = 665) and n‐C₂₈‐acid (R² = 0.74, n = 242). Tropical Pacific δ²H_Wax values fall within the predicted range of values based on the global calibration, and the largest residuals from the global regression line are no greater than those observed elsewhere, despite large uncertainties in δ²H_P values at some Pacific sites. However, tropical Pacific δ²H_Wax values in isolation are not correlated with estimated δ²H_P values from isoscapes or from isotope‐enabled general circulation models. Palynological analyses from these same Pacific sediment samples suggest no systematic relationship between any particular type of pollen distribution and deviations from the global calibration line. Rather, the poor correlations observed in the tropical Pacific are likely a function of the small range of δ²H_P values relative to the typical residuals around the global calibration line. Our results suggest that δ²H_Wax values are currently most suitable for use in detecting large changes in precipitation in the tropical Pacific and elsewhere, but that ample room for improving this threshold exits in both improved understanding of δ²H variability in plants, as well as in precipitation.

中文翻译：

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叶蜡氢同位素作为热带太平洋中的水文气候替代物

沉积叶蜡的氢同位素比率（δ ^2个ħ_蜡值）被越来越多地用于重建过去hydroclimate。在这里，我们增加δ ² ^ h_蜡从19个湖泊和15个热带太平洋岛屿，从表面沉积物和土壤公布数据的更新后的全球汇编4个沼泽值。全球范围内，有δ之间有很强的正的线性相关²年平均降雨量h的值（δ ^2个ħ _P值）和叶蜡Ñ -C ₂₉烷烃（- [R ²  = 0.74，Ñ  = 665）和Ñ -C ₂₈酸（R²  = 0.74，n  = 242）。热带太平洋δ ² ^ h_蜡值落在基于全局校准值的预测范围之内，并从全球回归线的最大残留不大于那些在其他地方看到，尽管δ较大的不确定性² ^ h _P在一些太平洋网站价值。然而，热带太平洋δ ^2个ħ_蜡在隔离值与估计的δ是不相关的² ħ _P来自等值线或启用同位素的一般循环模型的值。从这些相同的太平洋沉积物样本进行的孢粉学分析表明，任何特定类型的花粉分布与偏离全球校准线之间都没有系统的关系。相反，在热带地区中观察到的相关性差有可能小范围δ的函数² ħ _P值相对于周围的全局校准线的典型残差。我们的研究结果表明，δ ² ^ h_蜡值是目前最适合用于检测沉淀在热带太平洋和其他地区的巨大变化使用，但充足的空间以δ既提高了认识提高这个门槛退出²植物以及降水中H的变异性。