In this paper we explore a speleothem δ¹⁸O record from Palestina cave, northwestern Peru, at a site on the eastern side of the Andes cordillera, in the upper Amazon Basin. The δ¹⁸O record is interpreted as a proxy for South American Summer Monsoon (SASM) intensity and allows the reconstruction of its variability during the last 1600 years. Two periods of anomalous changes in the climate mean state corresponding to the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA) periods identified in the Northern Hemisphere are recognized in the record, in which decreased and increased SASM activity, respectively, have been documented. Variations in SASM activity between the MCA and the LIA seem to be larger over the northern part of the continent, suggesting a latitudinal dependence of the MCA footprint. Our results, based on time series, composite and wavelet analyses, suggest that the Atlantic Multidecadal Oscillation (AMO) plays an relevant role for SASM modulation on multidecadal scales (∼65 years), especially during dry periods such as the MCA. Composite analyses, applied to evaluate the influence of the AMO on the Palestina cave δ¹⁸O and other δ¹⁸O-derived SASM reconstructions, allow insight into the spatial footprints of the AMO over tropical South America and highlight differences between records during key studied periods. This work also reveals that replicating regional climate signals from different sites, and using different proxies is absolutely essential for a comprehensive understanding of past changes in SASM activity.

Karst aquifers provide drinking water for 10% of the world’s population, support agriculture, groundwater-dependent activities, and ecosystems. These aquifers are characterised by complex groundwater-flow systems, hence, they are extremely vulnerable and protecting them requires an in-depth understanding of the systems. Poor data accessibility has limited advances in karst research and realistic representation of karst processes in large-scale hydrological studies. In this study, we present World Karst Spring hydrograph (WoKaS) database, a community-wide effort to improve data accessibility. WoKaS is the first global karst springs discharge database with over 400 spring observations collected from articles, hydrological databases and researchers. The dataset’s coverage compares to the global distribution of carbonate rocks with some bias towards the latitudes of more developed countries. WoKaS database will ensure easy access to a large-sample of good quality datasets suitable for a wide range of applications: comparative studies, trend analysis and model evaluation. This database will largely contribute to research advancement in karst hydrology, supports karst groundwater management, and promotes international and interdisciplinary collaborations.

In the Amazon basin, intense precipitation recycling across the forest significantly modifies the isotopic composition of rainfall (δ¹⁸O, δD). In the tropical hydrologic cycle, such an effect can be identified through deuterium excess (dxs), yet it remains unclear what environmental factors control dxs, increasing the uncertainty of dxs‐based paleoclimate reconstructions. Here we present a 4‐year record of the isotopic composition of rainfall, monitored in the northwestern Amazon basin. We analyze the isotopic variations as a function of the air mass history, based on atmospheric back trajectory analyses, satellite observations of precipitation upstream, leaf area index, and simulated moisture recycling along the transport pathway. We show that the precipitation recycling in the forest exerts a significant control on the isotopic composition of precipitation in the northwestern Amazon basin, especially on dxs during the dry season (r = 0.71). Applying these observations to existing speleothem and pollen paleorecords, we conclude that winter precipitation increased after the mid‐Holocene, as the expansion of the forest allowed for more moisture recycling. Therefore, forest effects should be considered when interpreting paleorecords of past precipitation changes.