Recent soil moisture (SM) reconstructions revealed plunging trends and enhanced SM-temperature couplings over the last two decades in dry regions. However, how SM changed and whether the land-atmosphere interaction was intensified over time in humid regions remained unknown. Here we reported the first six-century-long regional summer SM reconstruction (1360–2000 CE) in western Europe (WE) using three individual tree-ring δ¹⁸O chronologies in England and France. A sharp wet-to-dry change occurred around 1820, earlier than 1850–1900 CE, the commonly used historical baseline of anthropogenic climate changes. Enhanced coupling of SM-temperature followed, with stronger summer sea level pressure anomalies in dry years after the 1820s. Our results reveal that the hotter-drier regime has also become more frequent in humid WE under global warming.

中文翻译：

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1820 年代标志着自 1360 年以来西欧向更干热的夏季转变

最近的土壤水分 (SM) 重建揭示了过去二十年来干旱地区的暴跌趋势和增强的 SM-温度耦合。然而，在潮湿地区，SM如何变化以及陆气相互作用是否随着时间的推移而加剧仍然未知。^{在这里，我们使用三个单独的年轮 δ 18}报告了西欧（WE）第一个长达六个世纪的区域夏季 SM 重建（公元 1360-2000 年）O 英国和法国的年表。1820 年左右发生了急剧的干湿变化，早于公元 1850-1900 年，这是人为气候变化的常用历史基线。紧随其后的是 SM 温度的耦合增强，在 1820 年代之后的干旱年份夏季海平面压力异常更强。我们的研究结果表明，在全球变暖的情况下，在潮湿的 WE 中，更热更干燥的状态也变得更加频繁。