Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century-猫眼课题宝

DOI：

10.1073/pnas.2002411117

发表时间：

2020-07

期刊：

Proceedings of the National Academy of Sciences of the United States of America

影响因子：

11.1

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

M. Morales;E. Cook;J. Barichivich;D. Christie;R. Villalba;C. LeQuesne;A. Srur;M. E. Ferrero;Á. González-Reyes;F. Couvreux;V. Matskovsky;J. Aravena;A. Lara;I. Mundo;Facundo Rojas;M. Prieto;J. Smerdon;L. Bianchi;M. Masiokas;R. Urrutia‐Jalabert;M. Rodriguez‐Caton;A. Muñoz;M. Rojas-Badilla;C. Álvarez;L. López;B. Luckman;D. Lister;I. Harris;P. Jones;A. P. Williams;G. Velazquez;D. Aliste;I. Aguilera-Betti;E. Marcotti;Felipe Flores;T. Muñoz;E. Cuq;J. Boninsegna

重要意义SADA是南美洲每年一次的水文气候图集，从公元1400年到2000年横跨南美洲12°S以南的大陆。基于286个树木年轮记录和基于仪器的土壤湿度估计，SADA补充了全球六个干旱地图集，填补了南半球的地理空白。SADA通过历史记录进行了独立验证，表明自20世纪60年代以来大范围严重干旱和极端暴雨的频率是前所未有的。SADA中表达的主要水文气候事件与强烈的厄尔尼诺南方涛动(ENSO)和南环状模式(SAM)异常有关。由于温室气体排放的增加，ENSO-SAM异常加上副热带低空急流的加强，可能会在21世纪造成南美洲更多的极端干旱和暴雨。南美(SA)社会非常容易受到干旱和暴雨的影响，但缺乏长期气候观测严重限制了我们对推动该地区气候变化的全球过程的理解。近几十年来，SA气候敏感年轮年表的数量和质量显著增加，现在提供了一个由286条记录组成的强大网络，用于描述自公元1400年以来的水文气候变化。我们将这个网络与一个自校准的Palmer干旱严重性指数(ScPDSI)数据集结合起来，得到了南美洲12°S以南大陆上的南美洲干旱地图集(SADA)。南半球夏季scPDSI的网格化年度重建是迄今为止对南美洲水文气候的最完整的空间估计，与过去的历史干湿事件很好地匹配。将SADA与澳大利亚-新西兰干旱地图集、海面温度和大气压力场联系起来，我们确定厄尔尼诺-南方涛动(ENSO)和南环模(SAM)与过去几个世纪SADA领域的空间扩展的干旱和暴雨密切相关。自20世纪中叶以来，SADA还出现了更多持续时间更长的严重干旱和极端暴雨。大范围的干旱与20世纪观测到的伴随着中纬度西风带减弱的正SAM异常的趋势是一致的，而全球变暖加剧的低层水汽输送有利于副热带地区的极端降雨。因此，SADA为观测到的水文气候变化和21世纪政府间气候变化专门委员会(IPCC)的预测提供了一个长期背景，这些预测表明，由于温室气体排放的增加，南澳将经历更频繁/严重的干旱和降雨事件。

Significance The SADA is an annually-resolved hydroclimate atlas in South America that spans the continent south of 12°S from 1400 to 2000 CE. Based on 286 tree ring records and instrumentally-based estimates of soil moisture, the SADA complements six drought atlases worldwide filling a geographical gap in the Southern Hemisphere. Independently validated with historical records, SADA shows that the frequency of widespread severe droughts and extreme pluvials since the 1960s is unprecedented. Major hydroclimate events expressed in the SADA are associated with strong El Niño Southern Oscillation (ENSO) and Southern Annular Mode (SAM) anomalies. Coupled ENSO-SAM anomalies together with subtropical low-level jet intensification due to increasing greenhouse gas emissions may cause more extreme droughts and pluvials in South America during the 21st century. South American (SA) societies are highly vulnerable to droughts and pluvials, but lack of long-term climate observations severely limits our understanding of the global processes driving climatic variability in the region. The number and quality of SA climate-sensitive tree ring chronologies have significantly increased in recent decades, now providing a robust network of 286 records for characterizing hydroclimate variability since 1400 CE. We combine this network with a self-calibrated Palmer Drought Severity Index (scPDSI) dataset to derive the South American Drought Atlas (SADA) over the continent south of 12°S. The gridded annual reconstruction of austral summer scPDSI is the most spatially complete estimate of SA hydroclimate to date, and well matches past historical dry/wet events. Relating the SADA to the Australia–New Zealand Drought Atlas, sea surface temperatures and atmospheric pressure fields, we determine that the El Niño–Southern Oscillation (ENSO) and the Southern Annular Mode (SAM) are strongly associated with spatially extended droughts and pluvials over the SADA domain during the past several centuries. SADA also exhibits more extended severe droughts and extreme pluvials since the mid-20th century. Extensive droughts are consistent with the observed 20th-century trend toward positive SAM anomalies concomitant with the weakening of midlatitude Westerlies, while low-level moisture transport intensified by global warming has favored extreme rainfall across the subtropics. The SADA thus provides a long-term context for observed hydroclimatic changes and for 21st-century Intergovernmental Panel on Climate Change (IPCC) projections that suggest SA will experience more frequent/severe droughts and rainfall events as a consequence of increasing greenhouse gas emissions.

Six hundred years of South American tree rings reveal an increase in severe hydroclimatic events since mid-20th century

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