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.

南美社会非常容易遭受干旱和小雨的侵袭，但是缺乏长期的气候观测资料严重限制了我们对导致该地区气候变化的全球过程的理解。近几十年来，SA对气候敏感的树年轮年表的数量和质量显着增加，现在提供了286条记录的强大网络，用于表征自1400年以来的水气候变化特征。我们将此网络与自校准的Palmer干旱严重程度指数（scPDSI）数据集结合起来，得出12°S以南大陆上的南美干旱地图集（SADA）。夏季南澳夏季大尺度降水预报的网格化重建是迄今为止南半球水文气候在空间上最完整的估计，与过去的干湿事件历史相吻合。通过将SADA与澳大利亚-新西兰干旱地图集，海面温度和大气压力场相关联，我们确定厄尔尼诺-南方涛动（ENSO）和南部环状模式（SAM）与空间扩展的干旱和干旱带密切相关。过去几个世纪以来的SADA领域。自20世纪中叶以来，SADA还表现出更为严重的干旱和极端干旱。广泛的干旱与20世纪观测到的正SAM异常趋势伴有中纬度西风的减弱相一致，而全球变暖加剧的低水平水汽输送有利于整个亚热带地区的极端降雨。