Browsing by Author "Meseguer-Ruiz, Oliver"

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    Andean peatlands at risk? Spatiotemporal patterns of extreme NDVI anomalies, water extraction and drought severity in a large-scale mining area of Atacama, northern Chile
    (2023) Chavez, Roberto O.; Meseguer-Ruiz, Oliver; Olea, Matias; Calderon-Seguel, Matias; Yager, Karina; Isela Meneses, Rosa; Lastra, Jose A.; Nunez-Hidalgo, Ignacio; Sarricolea, Pablo; Serrano-Notivoli, Roberto; Prieto, Manuel
    In the Andes, multiple human and climatic factors threaten the conservation of bofedales, a type of high altitude peat forming wetland widely distributed in the tropical and subtropical Andes. In northern Chile, climate change and water extraction for industrial activities are among the most significant threats to these relevant socio-hydrological systems hosting indigenous pastoral communities. In this study, we present an integrated anal-ysis of Normalized Difference Vegetation Index (NDVI) anomalies, drought severity and water rights granted to industry to provide insight on the conservation status of bofedales, historical drivers of their transformation, and current threats. Using Landsat satellite imagery from 1986 to 2018, we identify spatio-temporal NDVI changes of 442 bofedales in one of the leading copper producing regions of the world. The NDVI time series analysis over 32 growing seasons was used to detect extreme anomalies, i.e. values outside the 95 % of the reference frequency distribution, indicating periods of extreme changes in the productivity of these high Andes wetlands. To evaluate the relationship between bofedales NDVI extreme periods to drought and continued water extraction activities, we combine a climate-based multi-temporal-scale drought index (SPEI) with the geospatial latitudinal distri-bution of water rights granted for extractive industries in the study area. Over the time period of analysis, the total amount of granted water rights increased 465 % from 1,201 l/s recorded before 1985 to 5,584 l/s in 2018. In the areas where the highest amount of water rights are concentrated, i.e. between 21.3 degrees S and 22.1 degrees S, "green" bofedales (NDVI>=0.23) are practically absent. NDVI of the austral summer (JFM) was highly correlated with the severity of drought occurring during the three months of the growing season peak. While our findings show bofedal productivity is mostly influenced by precipitation and temperature of the wet season (JFM) during the study period, results also raise questions regarding possible bofedal loss occurring over the previous 80 years prior to the satellite record, wherein water extraction activities have significantly increased according to official records.
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    General dry trends according to the standardized precipitation evapotranspiration index in mainland Chile
    (2024) Meseguer-Ruiz, Oliver; Serrano-Notivoli, Roberto; Nunez-Hidalgo, Ignacio; Sarricolea, Pablo
    Droughts are one of the main challenges affecting humanity in a global change context. Due to its spatial configuration, Chile experiences droughts of different severities, from arid to humid climates, ranging from sea level to elevations above 6,000 m above sea level (a.s.l.), but it is still unknown how this phenomenon behaves in distribution, duration and intensity. The goal of this study is to identify how droughts have affected the different climate regions of the country between 1979 and 2019. The Standardized Precipitation Evapotranspiration Index (SPEI), calculated for March and September, at the end of the humid season in the north and center-south of the country, respectively, and calculated at 3-, 6-, 9-, 12- and 24-month, allowed to determine the trends of the drought severity in a 5 x 5 km grid between 1979 and 2019. We found that negative and significant trends, indicating dry conditions, appear mainly in the Andes above 2,000 m a.s.l., where the main water reservoirs are located, affecting all climate types, except Mediterranean ones between 33 degrees S and 38 degrees S. The SPEI indicates general trends towards drier conditions across various elevations and climate types, with more pronounced negative trends in the north and central regions and some positive trends in the south. These trends suggest a significant impact on water availability, and highlight the need for focused policy initiatives to combat drought effects and manage water resources effectively. These findings are of main interest to Chile, one of the world's leading producers of lithium and copper, with both industries requiring substantial amounts of water for extraction and processing, demanding high water availability in a drier territory.
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    Hydroclimate variations over the last 17,000 years as estimated by leaf waxes in rodent middens from the south-central Atacama Desert, Chile
    (2023) Frugone-Alvarez, Matias; Contreras, Sergio; Meseguer-Ruiz, Oliver; Tejos, Eduardo; Delgado-Huertas, Antonio; Valero-Garces, Blas; Diaz, Francisca P.; Briceno, Matias; Bustos-Morales, Manuel; Latorre, Claudio
    Leaf cuticular waxes are one of the most important environment-plant interaction structural systems that enable desert plants to withstand extreme climatic conditions. We present a long chain n-alkyl lipids study in fresh plant leaves and rodent palaeomiddens collected along an elevational gradient in the south-central Atacama Desert of Chile, covering six different vegetation belts: Steppe (4500-4000 m asl), Puna (4000-3300 m asl), pre-Puna (3300-2400 m asl), Absolute Desert (2400-1000 m asl) and Coastal Desert (1000-0 m asl). The 28 rodent palaeomiddens analyzed from Quebrada Incahuasi (25.6 & DEG;S, 3600 m asl) span the last 17,000 years. Modern-day distribution of long-chain n-alkanes and n-alkanoic acids varies among the dominant plant associations of the Atacama Desert. These plants show a species -specific chemotaxonomy linked to the climatic conditions. Furthermore, differences in average chain length (ACL) and carbon preference index (CPI) suggest that these plant communities are highly adapted to extreme environmental conditions. The sum of leaf wax n-alkanes was highest under wet conditions, while n-alkanoic acids (between n -C24 and n -C28) increased with hyperaridity. Similarly, analysis of n- alkane time series from palaeomiddens showed that the greatest changes in leaf wax n-alkane distri-butions (ACL and CPI) corresponded to the greatest increases in moisture during the Central Andean Pluvial Event (CAPE; between 18 and 9 ka cal BP) and the Late Holocene. The shift in the palaeomidden n- alkane distributions is corroborated by the relative abundance of rainfall-dependent extra-local taxa. This is the first study to report leaf wax content obtained from ancient rodent middens, and shows promising results as a robust hydroclimate proxy for the Atacama Desert region. & COPY; 2023 Published by Elsevier Ltd.
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    Population dynamics shifts by climate change: High-resolution future mid-century trends for South America
    (2023) Nunez-Hidalgo, Ignacio; Meseguer-Ruiz, Oliver; Serrano-Notivoli, Roberto; Sarricolea, Pablo
    Population dynamics and climate change are the main challenges for the 21st century, especially in South America. Human populations will increase their exposure to novel climatic conditions in their territories, entangling and complicating health and social problems. We analyze how socioeconomic and climatic future pathways will evolve in South America, a land with high climatic and social heterogeneity. We use the Koppen-Geiger climate classification, population growth, and climate projections for the most likely climate change scenarios for the 2050s based on the CHELSA dataset. We found that tropical and arid climates extend between 4.2%-2.5% and 2.6%-3.9%, replacing temperate climate zones, which will be reduced between 5.3%-4.5% for the Representative Concentration Pathways (RCP) 4.5 and 8.5 respectively. This implies a reduction of the Mediterranean, oceanic and polar climates. Population growth shows a significant relationship to increasing tropical and arid climates extension in almost all countries, meaning a higher exposure to more severe conditions for humans. This work opens up the chance of using possible guidelines to assist environmental management with key background information on expected climate types and population changes and address the potential effects of climate change on human settlements in the near future.