Reconstruction of past conditions provides important information on how ecosystems have been impacted by climate change, but generally for microhabitats worldwide there are no long-term empirical measurements. In these cases, there has been protracted debate about how various large-scale environmental proxies can best be used to reconstruct local temperatures. Here we help resolve this debate by examining how well environmental proxies hindcast sand temperatures at nest depths for five sea turtle nesting sites across the world. We link instrumental air temperature and sea surface temperature records with empirical sand temperature observations in the Atlantic (Ascension Island and Cape Verde), the Indian Ocean (Chagos Archipelago), the Caribbean (St Eustatius) and the Pacific (French Polynesia). We found strong correlations between sea surface temperatures, air temperatures and sand temperatures at all our study sites. Furthermore, Granger causality testing shows variations in sea surface temperature and air temperature precede variations in sand temperatures. We found that different proxies (air or sea temperature or a combination of both) predicted mean monthly sand temperatures within <0.5°C of empirical observations. Reconstructions of sand temperatures over the last 170 years reveal a slight warming of temperatures (maximum 0.5°C per century). An analysis of 36 published datasets revealed that the gradient of the relationship between sand temperature and air temperature is relatively constant, suggesting long-term changes in sand temperature could be extended around the world to include nesting sites where there are no empirical measurements of sand temperature. Our approaches are likely to have utility for a range of microhabitats where there is an interest in long-term changes in temperature.

中文翻译：

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重建海滩小气候中过去的热条件

过去条件的重建提供了关于生态系统如何受到气候变化影响的重要信息，但对于全世界的微型栖息地，通常没有长期的经验测量。在这些情况下，关于如何最好地使用各种大规模环境代理来重建局部温度一直存在长期争论。在这里，我们通过检查环境代理对世界各地五个海龟筑巢地点的巢穴深度的沙子温度的影响程度来帮助解决这一争论。我们将仪器气温和海面温度记录与大西洋（阿森松岛和佛得角）、印度洋（查戈斯群岛）、加勒比海（圣尤斯特歇斯）和太平洋（法属波​​利尼西亚）的经验沙温观测联系起来。我们发现所有研究地点的海面温度、气温和沙温之间存在很强的相关性。此外，格兰杰因果检验表明海面温度和气温的变化先于沙温的变化。我们发现，不同的代理（空气或海水温度或两者的组合）预测的月平均沙温在经验观察 <0.5°C 以内。过去 170 年的沙地温度重建显示温度略有升高（每世纪最高 0.5°C）。对 36 个已发布数据集的分析表明，沙温与气温之间的关系梯度相对恒定，建议沙温的长期变化可以扩展到世界各地，包括没有沙温经验测量的筑巢地点。我们的方法可能适用于一系列对温度长期变化感兴趣的微型栖息地。