Climate change is expected to decrease mean precipitation in California, but changes in hydroclimate extremes are likely to have more immediate and significant impacts on California water resources, ecosystems, and economy. Paleoclimate records can provide valuable baseline data for constraining natural hydroclimate variability and improving climate projections, but quantitative precipitation records are limited. A new study by de Wet et al. (2021) provides the first semi-quantitative record of early Holocene precipitation in central California, based on speleothem calcium isotope (δ⁴⁴Ca) variations, that indicates that precipitation variability during and preceding the 8.2 kyr event approached or exceeded that of recent decades. This study outlines a new approach for developing more robust and quantitative hydroclimate records, and also highlights that precipitation “whiplash” is a ubiquitous feature of California's climate that we must prepare for, especially given the likelihood that human-caused climate change is already increasing the frequency and severity of hydrologic extremes.

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加利福尼亚的挥发性水文气候：来自古气候记录的教训

气候变化预计将减少加利福尼亚的平均降水量，但极端水文气候的变化可能会对加利福尼亚的水资源、生态系统和经济产生更直接和重大的影响。古气候记录可以为限制自然水文气候变率和改善气候预测提供有价值的基线数据，但定量降水记录是有限的。de Wet 等人的一项新研究。(2021) 提供了加利福尼亚中部早期全新世降水的第一个半定量记录，基于 speleothem 钙同位素 (δ ⁴⁴Ca) 变化，这表明 8.2 kyr 事件期间和之前的降水变化接近或超过了近几十年来的变化。这项研究概述了一种开发更可靠和定量的水文气候记录的新方法，并强调了降水“鞭打”是加州气候的一个普遍特征，我们必须为此做好准备，特别是考虑到人为气候变化的可能性已经增加了水文极端事件的频率和严重程度。