Since 2010, Chile has experienced one of the most severe droughts over the last century, the so-called mega-drought (MD). The MD conditions, combined with intensive agricultural activities and the current water management system, have led to water scarcity problems in Mediterranean and Semi-arid regions of Chile. An emblematic case is the Petorca basin, where a water crisis is undergone. To characterize this crisis, we analyzed water provision by using tree-ring records, remote sensing, instrumental data, and allocated water rights within the basin. Results indicate that the MD is the most severe dry period over the last 700-years of streamflow reconstruction. During the MD, streamflow and water bodies of the upper parts of the basin have been less affected than mid and low areas of this valley, where consumptive withdrawals reach up to 18% of the mean annual precipitation. This extracted volume is similar to the MD mean annual precipitation deficits. The impacts of the current drought, along with the drier climate projections for Central Chile, emphasize the urgency for faster policy changes related to water provision. Climate change adaptation plans and policies should enhance the current monitoring network and the public control of water use to secure the water access for inhabitants and productive activities.

The Anthropocene is an uneven phenomenon. Accelerated shifts in the functioning of the Earth System are mainly driven by the production and consumption of wealthy economies. Social, environmental and health costs of such industrialization, however, bear on low‐income communities inhabiting severely degraded territories by polluting activities (i.e., sacrifice zones). How global, national and local socio‐economic and governance processes have interacted in perpetuating socio‐environmental inequalities in these territories has been rarely explored. Here, we develop an historical quantitative approach integrating a novel chemostratigraphic record, data on policy making, and socio‐economic trends to evaluate the feedback relationship between environmental injustice and Anthropocene in sacrifice zones. We specifically outline a case study for the Puchuncaví valley ‐one of the most emblematic sacrifice zones from Chile‐. We verify an ever‐growing burden of heavy metals and metalloids over the past five decades paced by the staggering expansion of local industrial activities, which has ultimately been spurred by national and transnational market forces. Local poverty levels have declined concomitantly, but this path toward social equality is marginal as costs of pollution have grown through time. Indeed, national and international pollution control actions appear insufficient in mitigating the cumulative impact brought by highly toxic elements. Thus, our sub‐decadal reconstruction for pollution trends over the past 136 years from a sediment record, emerges as a science‐based tool for informing the discussion on Anthropocene governance. Furthermore, it helps to advance in the assessment of environmental inequality in societal models that prioritize economic growth to the detriment of socio‐environmental security.

Forests play an important role in water and carbon cycles in semiarid regions such as the Mediterranean ecosystems. Previous research in the Chilean Mediterranean forests revealed a break point in 1980 in regional tree-ring chronologies linked to climate change. However, it is still unclear which populations and age classes are more affected by recent increases in drought conditions. In this study, we investigated the influence of recent variations in precipitation, temperature, and CO₂ concentrations on tree growth of various populations and age classes of Nothofagus macrocarpa trees in Central Chile. We sampled 10 populations from five sites of N. macrocarpa through its whole geographic distribution in both Coastal and Andes ranges. We used standard dendrochronological methods to (i) group populations using principal component analysis, (ii) separate age classes (young, mature, and old trees), (iii) evaluate linear growth trends based on the basal area increment (BAI), and (iv) analyze the link between BAI and atmospheric changes using linear mixed-effects models. Results showed that young trees are more sensitive to climate variability. Regarding population grouping, we observed that all population clusters were sensitive to winter-spring precipitation, but only the Andes and Coastal populations were negatively correlated with temperature. The results of CO₂ fertilization analyses were controversial and unclear. Since young trees from all population clusters reacted positively in the phase with an increase of atmospheric CO₂ between 1980 and 2014, this behavior was not translated into growth for the last 15 years (2000–2014). However, it should be noted that the young trees of the highest elevation populations did not have a negative growth trend, so it seems that CO₂ counteracted the negative effect of recent regional climate change (increase in temperature and precipitation decrease) in these population trees. Further studies are needed to assess the effects of climate variability over other ecological and physiological processes.

Tree-ring research (TRR) in South America (SA) continues to make important contributions in multiple sub-disciplines, including dendrochemistry and dendrohydrology. This report describes some of the advances in TRR in SA presented in a two-day International Meeting Research entitled “An International Network to Promote Advances in Dendrochronology in South America”, organized by the Laboratory of Dendrochronology and Environmental Studies of the Pontifical Catholic University of Valparaíso in Valparaíso, Chile, on January 21–22, 2019. The objective of the meeting was to communicate recent advances in TRR within a network of laboratories in Argentina, Brazil, Chile, Peru, and Uruguay. Novel methodologies and results in dendrochemistry and wood anatomy were also presented by collaborating researchers from German institutions. This report describes some of the research within the subdisciplines of tree-ring science, including dendrochemistry, anatomy and dendrohydrology, and their application to understanding spatio-temporal variability in heavy metal contamination, climate, hydrology, fire regimes and other critical components of South American forest and woodland ecosystems. The meeting demonstrated expansion and diversification of inquiry and applications of TRR in SA, whereby collaboration across research centers has been critical for the advances made in broad-scale comparative studies as well as multi-proxy approaches and the study of global and hemisphere-scale climate phenomena.