Browsing by Author "Lambert, Fabrice"

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    Desalinización: oportunidades y desafíos para abordar la inseguridad hídrica en chile
    (Ministerio de Ciencia, Tecnología, Conocimiento e Innovación, 2022) Vicuña, Sebastián; Daniele, Linda; Farías, Laura; González, Humberto; Marquet, Pablo A.; Palma Behnke, Rodrigo; Stehr, Alejandra; Urquiza, Anahí; Wagemann, Elizabeth; Arenas Herrera, María J.; Bórquez, Rodrigo; Cornejo Ponce, Lorena; Delgado, Verónica; Etcheberry, Gabriel; Fragkou, María Christina; Fuster, Rodrigo; Gelcich, Stefan; Melo, Óscar; Monsalve, Tamara; Olivares, Marcelo; Ramajo, Laura; Ramírez Pascualli, Carlos; Rojas, Carolina; Rojas, Christian; Vilca Salinas, Patricia; Winckler, Patricio; Winckler, Patricio; Lambert, Fabrice
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    Dust transport enhanced land surface weatherability in a cooling world
    (European Association of Geochemistry, 2023) Yang, Y.; Galy, A.; Zhang, J.; Lambert, Fabrice; Zhang, M.; Zhang, F.; Fang, X.
    The weatherability of exposed silicate rocks drives the efficiency of climatic feedback on the geological carbon cycle through silicate weathering. However, the controls and evolution of land surface weatherability are not fully understood. Tectonically induced exposure of fresh silicates can induce a wide range of weatherability, depending on the maturity and lithology of the exhumed rocks. Here, we propose that aeolian dust has potentially been pivotal in sustaining land surface weatherability during global cooling. Our analysis of palaeoclimate simulations shows an additional transport of 1072 ± 69 Tg yr−1 of dust to regions with precipitation of more than 400 mm yr−1 during the Last Glacial Maximum compared to the pre-industrial period. As dust mainly contains fresh minerals with high surface areas, such dust transport markedly increases land surface weatherability, yielding an additional atmospheric CO2 consumption of 0.431 ± 0.030 Tmol yr−1, which would offset the reduced silicate weathering induced by weaker climatic forcing. It is suggested that a dustier world could increase global land surface weatherability, leading to a more buffered carbon cycle that sustained low atmospheric CO2 levels.
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    Environmental evolution of western Tierra del Fuego (∼54°S) since ice-free conditions and its zonal/hemispheric implications
    (2023) Moreno, Patricio I.; Lambert, Fabrice; Hernández, Loreto; Villa Martínez, Rodrigo P.
    By virtue of its position adjacent to the Drake Passage, Tierra del Fuego in South America allows examining the vegetation and environmental history of the southernmost continental landmass outside Antarctica, and the evolution of the Southern Westerly Winds-Southern Ocean (SWW–SO) coupled system since the Last Glacial Maximum (LGM). For that purpose, we studied sediment cores from Lago Charquito, a small closed-basin lake in central-west Tierra del Fuego with a continuous lacustrine record since ~17.3 ka. Ice-free conditions at the site imply a ~70 km retreat of the Bahía Inútil glacier lobe from its LGM position during a ~800-year interval, a trend that continued until its disappearance ~100 km upstream from L. Charquito, ~800 years later. Our palynological data show an open landscape dominated by cold-tolerant shrubs and herbs between ~17.3–12.9 ka, with increases in precipitation of SWW origin at ~16.3 ka, ~14.7 ka, between ~8.7–7.6 ka, and after ~6.8 ka. Warming at ~12.9 ka initiated an abrupt afforestation trend that stalled during the early Holocene (~12–8.7 ka) owing to a precipitation decline and wildfires, and later resumed in response to invigorated SWW. We hypothesize that sparse Nothofagus tree populations inhabited the periphery of the Patagonian Ice Sheet (PIS) during the LGM and migrated toward the Andes contemporaneous with glacier recession as temperature rose during the Last Glacial Termination (T1). We posit that besides establishing topographic and climatic barriers for land biota, the PIS enabled the connectivity of cold-tolerant hygrophilous plant populations along a humid fringe adjacent to its land-based perimeter, despite the presumably dry conditions downwind from the eastern PIS margin. Our results suggest that southward shifts or expansion of the SWW toward or beyond Tierra del Fuego enhanced upwelling and ventilation of deep waters in the SO, northward shifts or weakening had the opposite effect. We observe that the time evolution of atmospheric CO2 concentrations, high-latitude air and sea-surface temperatures, and sea level during T1 fall short in explaining the timing and abruptness of the Bahía Inútil glacier lobe collapse, and quite possibly multiple other glacier lobes from the PIS.
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    Geographic variability of dust and temperature in climate scaling regimes over the Last Glacial Cycle
    (2023) Acuña Reyes, Nicolas Martin; Van T Wout, Elwin; Lambert, Fabrice; Lovejoy, Shaun
    Temperature and mineral dust records serve as valuable paleoclimate indicators for studying atmospheric variability across a wide range of temporal scales. Due to the typically lower resolution of older sections within these records, studies investigating the geographical variability of the atmosphere have predominantly focused on periods shorter than one glacial cycle, such as the Holocene or the Last Glacial Maximum. In this study, we utilise a Haar-based algorithm to evaluate the geographic variability of dust and temperature records throughout the last glacial cycle. This algorithm enables us to analyse non-equidistant sampling series, allowing for the utilisation of both high and low-frequency information from the records. Consequently, we can investigate timescales ranging from decades to thousands of years. Notably, our findings indicate that the transition from macroweather to climate regimes occurs at shorter timescales in polar regions compared to the tropics or mid-latitudes. Furthermore, disparities between the dust records of the North and South Poles were observed. Finally, we assess the time-dependent correlation between the polar regions and the lower latitudes. Our analysis reveals high correlations at timescales of approximately 20, 40, and 100 kyr, which aligns with the Milankovitch cycles. Conversely, all sites exhibit a loss of correlation between 40 and 80 kyr, indicating the absence of an identifiable oscillation synchronisation mechanism at these scales. On the one hand, our findings support the use of the Haar-based method as an alternative for analysing nonuniform datasets. On the other hand, they underscore the necessity for additional high-resolution or longer time series data from the tropics or mid-latitudes, as the currently available data fail to adequately represent the glacial-interglacial cycles.