Iberia is predicted under future warming scenarios to be increasingly impacted by drought. While it is known that this region has experienced multiple intervals of enhanced aridity over the Holocene, additional hydroclimate-sensitive records from Iberia are necessary to place current and future drying into a broader perspective. Toward that end, we present a multi-proxy composite record from six well-dated and overlapping speleothems from Buraca Gloriosa (BG) cave, located in western Portugal. The coherence between the six stalagmites in this composite stalagmite record illustrates that climate (not in-cave processes) impacts speleothem isotopic values. This record provides the first high-resolution, precisely dated, terrestrial record of Holocene hydroclimate from west-central Iberia. The BG record reveals that aridity in western Portugal increased secularly from 9.0 ka BP to present, as evidenced by rising values of both carbon (δ13C) and oxygen (δ18O) stable isotope values. This trend tracks the decrease in Northern Hemisphere summer insolation and parallels Iberian margin sea surface temperatures (SST). The increased aridity over the Holocene is consistent with changes in Hadley Circulation and a southward migration of the Intertropical Convergence Zone (ITCZ). Centennial-scale shifts in hydroclimate are coincident with changes in total solar irradiance (TSI) after 4 ka BP. Several major drying events are evident, the most prominent of which was centered around 4.2 ka BP, a feature also noted in other Iberian climate records and coinciding with well-documented regional cultural shifts. Substantially, wetter conditions occurred from 0.8 ka BP to 0.15 ka BP, including much of the ‘Little Ice Age’. This was followed by increasing aridity toward present day. This composite stalagmite proxy record complements oceanic records from coastal Iberia, lacustrine records from inland Iberia, and speleothem records from both northern and southern Spain and depicts the spatial and temporal variability in hydroclimate in Iberia.

中文翻译：

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全新世期间伊比利亚西部（葡萄牙）的水文气候变化：来自复合石笋同位素记录的见解

预计在未来的变暖情景下，伊比利亚将越来越受到干旱的影响。虽然众所周知，该地区在全新世经历了多次干旱加剧，但需要更多来自伊比利亚的水文气候敏感记录，才能将当前和未来的干旱置于更广阔的视野中。为此，我们展示了来自位于葡萄牙西部的 Buraca Gloriosa (BG) 洞穴的六个年代久远且重叠的洞穴群的多代理复合记录。该复合石笋记录中六个石笋之间的连贯性说明气候（不是洞穴内过程）影响洞穴同位素值。该记录提供了伊比利亚中西部全新世水气候的第一个高分辨率、精确日期的陆地记录。BG 记录显示，葡萄牙西部的干旱从 9.0 ka BP 长期增加到现在，碳 (δ13C) 和氧 (δ18O) 稳定同位素值的上升证明了这一点。这种趋势跟踪北半球夏季日照的减少，并与伊比利亚边缘海面温度 (SST) 平行。全新世干旱度的增加与哈德利环流的变化和热带辐合带 (ITCZ) 的向南迁移是一致的。百年尺度的水文气候变化与 4 ka BP 后总太阳辐照度 (TSI) 的变化一致。几个主要的干旱事件是明显的，其中最突出的集中在 4.2 ka BP 附近，这一特征在其他伊比利亚气候记录中也有记录，并与有据可查的区域文化转变相吻合。实质上，更潮湿的条件发生在 0.8 ka BP 到 0.15 ka BP 之间，包括“小冰河时代”的大部分时间。随之而来的是越来越干旱的今天。这个复合石笋替代记录补充了伊比利亚沿海的海洋记录、伊比利亚内陆的湖泊记录以及西班牙北部和南部的洞穴记录，并描述了伊比利亚水文气候的空间和时间变化。