Department of Geology and Planetary Science, University of Pittsburgh, 4107 O'Hara Street, SRCC Room 200, Pittsburgh, PA 15260-3332, USA.
Proc Natl Acad Sci U S A. 2012 Jul 17;109(29):11619-23. doi: 10.1073/pnas.1201083109. Epub 2012 Jul 2.
Multiple paleoclimate proxies are required for robust assessment of past hydroclimatic conditions. Currently, estimates of drought variability over the past several thousand years are based largely on tree-ring records. We produced a 1,500-y record of winter precipitation in the Pacific Northwest using a physical model-based analysis of lake sediment oxygen isotope data. Our results indicate that during the Medieval Climate Anomaly (MCA) (900-1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450-1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). These findings are somewhat discordant with drought records from tree rings, suggesting that differences in seasonal sensitivity between the two proxies allow a more compete understanding of the climate system and likely explain disparities in inferred climate trends over centennial timescales.
需要使用多种古气候代用指标来稳健地评估过去的水文气候条件。目前，过去几千年干旱变化的估计主要基于树木年轮记录。我们使用基于物理模型的湖泊沉积物氧同位素数据分析，生成了太平洋西北地区 1500 年的冬季降水记录。我们的结果表明，在中世纪气候异常期（MCA）（公元 900-1300 年），太平洋西北地区冬季异常湿润，而在小冰期（LIA）（公元 1450-1850 年）期间则较为干燥，这与沙漠西南部的水文气候异常形成对比，与厄尔尼诺南方涛动（ENSO）和太平洋年代际振荡（PDO）相关的气候动力一致。这些发现与树木年轮的干旱记录有些不一致，表明两种代用指标在季节敏感性上的差异可以更全面地了解气候系统，并可能解释在百年时间尺度上推断出的气候趋势的差异。
