Hydroclimate and ENSO Variability Recorded by Oxygen Isotopes From Tree Rings in the South American Altiplano

Rodríguez‐Catón, Milagros; Andreu‐Hayles, Laia; Daux, Valérie; Vuille, Mathias; Varuolo-Clarke, Arianna M.; Oelkers, Rose; Christie, Duncan A.; D’Arrigo, Rosanne; Morales, Mariano; Rao, Mukund Palat; Srur, Ana Marina; Vimeux, Françoise; Villalba, Ricardo

doi:10.1029/2021gl095883

Cited by 15 publications

(17 citation statements)

References 64 publications

(127 reference statements)

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“…The existing sub-decadally resolved oxygen isotope records spanning the last millennium (LM, 850-1850 CE) are known to be representative of re-gional variability related to the summer monsoon (Vuille et al, 2003;Vuille and Werner, 2005). High-resolution oxygen isotope paleorecords are widely available from archives in South America: ice cores in Andean glaciers (e.g., Thompson et al, 1985;Vimeux et al, 2009), lake sediment cores from closed basin lakes (e.g., Bird et al 2011), speleothems from karstic regions (e.g., Novello et al, 2018;Campos et al 2019), and tree rings in high-altitude regions (e.g., Baker et al, 2015;Rodriguez-Caton et al, 2022).…”

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South American Summer Monsoon variability over the last millennium in paleoclimate records and isotope-enabled climate models

et al. 2022

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Abstract. The South American Summer Monsoon (SASM) is the main driver of regional hydroclimate variability across tropical and subtropical South America. It is best recorded on paleoclimatic timescales by stable oxygen isotope proxies, which are more spatially representative of regional hydroclimate than proxies for local precipitation alone. Network studies of proxies that can isolate regional influences lend particular insight into various environmental characteristics that modulate hydroclimate, such as atmospheric circulation variability and changes in the regional energy budget as well as understanding the climate system sensitivity to external forcings. We extract the coherent modes of variability of the SASM over the last millennium (LM) using a Monte Carlo empirical orthogonal function (MCEOF) decomposition of 14 δ18O proxy records and compare them with modes decomposed from isotope-enabled climate model data. The two leading modes reflect the isotopic variability associated with (1) thermodynamic changes driving the upper-tropospheric monsoon circulation (Bolivian High–Nordeste Low waveguide) and (2) the latitudinal displacement of the South Atlantic Convergence Zone (SACZ). The spatial characteristics of these modes appear to be robust features of the LM hydroclimate over South America and are reproduced both in the proxy data and in isotope-enabled climate models, regardless of the nature of the model-imposed external forcing. The proxy data document that the SASM was characterized by considerable temporal variability throughout the LM, with significant departures from the mean state during both the Medieval Climate Anomaly (MCA) and the Little Ice Age (LIA). Model analyses during these periods suggest that the local isotopic composition of precipitation is primarily a reflection of upstream rainout processes associated with monsoon convection. Model and proxy data both point to an intensification of the monsoon during the LIA over the central and western parts of tropical South America and indicate a displacement of the South Atlantic Convergence Zone (SACZ) to the southwest. These centennial-scale changes in monsoon intensity over the LM are underestimated in climate models, complicating the attribution of changes on these timescales to specific forcings and pointing toward areas of important model development.

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South American Summer Monsoon variability over the last millennium in paleoclimate records and isotope-enabled climate models

et al. 2022

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“…Overall, positive precipitation anomalies coincide with comparably negative δ 18 O precip anomalies on the southern Altiplano even if the relation between precipitation amount and δ 18 O precip locally varies [ 56 , 57 ]. Significant negative correlations also appear on multi-decadal timescales between tree-ring δ 18 O chronologies from Polylepis tarapacana and precipitation amount in the Chilean and Bolivian Altiplano [ 59 ]. As the amount of precipitation is negatively correlated with δ 18 O precip , more negative (positive) δ 18 O values indicate increased (decreased) amounts of SASM precipitation [ 56 , 60 , 61 ].…”

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confidence: 99%

Hydroclimatic record from an Altiplano cushion peatland (24°S) indicates large-scale reorganisation of atmospheric circulation for the late Holocene

et al. 2022

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The hydroclimate of South America is characterized by the South American summer monsoon (SASM), a tropical atmospheric circulation that induces a summer precipitation regime, and the Southern Hemisphere Westerlies (SHW), an extratropical atmospheric circulation that induces a winter precipitation regime. Stretched between these two systems is a NW-SE-oriented region dominated by descending air masses, resulting in the South American subtropical dry zone (SASDZ), also known as the arid diagonal. We investigated the Cerro Tuzgle cushion peatland (CTP) located on the Argentine Altiplano, north of the present-day SASDZ. Previous work revealed that the CTP was consistently in the SASM regime during the last 2900 cal yr BP. Here, we extend the CTP record to the middle Holocene covering the last 7200 cal yr BP to gain further knowledge of the Holocene development of the SASM and potential modulations of the SASDZ. The prominent feature of the entire record is a distinct and lasting transition centred around 3100 cal yr BP characterized by declining minerogenic content, increasing organic carbon content, rising stable carbon isotope values of organic matter and cellulose, and increasing stable oxygen isotope values of cellulose. We interpret this specific proxy pattern as a hydroclimatic transition towards less arid conditions at the CTP after 3100 cal yr BP. The transition corresponds with the end of the continuous Holocene strengthening of the SASM between 3500 cal yr BP and 3000 cal yr BP indicated by proxy records from north and east of the CTP. The CTP does not reflect this strengthening of the SASM and rather exhibits a threshold response indicating the effective establishment of the SASM summer precipitation regime at 24°S. This suggests that moisture supply during a more arid middle Holocene was provided by isotopically depleted precipitation, while moisture supply after the transition originated from isotopically enriched SASM summer precipitation. Concurrent hydroclimatic changes in the SHW winter precipitation regime south of the SASDZ are documented in a distinct lake level rise of Laguna Aculeo (33°50´S) around 3200 cal yr BP. These coinciding hydrological changes of the SASM and the SHW precipitation regimes indicate larger scale reorganisations of atmospheric circulation components, potentially connected to major modulations of the SASDZ. Thus, our CTP record sheds light on the middle to late Holocene development of the SASM at its southern limit and corroborates connections between the tropical and extratropical hydroclimate of South America.

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“…By contrast, the oxygen isotope composition in wood cellulose houses information about changes in the δ 18 O of precipitation, capturing changes in wet-and dry-season rainfall and moisture supply. The δ 18 O of wood cellulose has been used to explore hydroclimate and ENSO variability (Boysen et al 2014) in the tropical Americas (Anchukaitis et al 2008, Anchukaitis and Evans 2010, Rodriguez-Caton et al 2022 and in Southeast Asia (Chenxi et al 2011, Zhu et al 2012. Cellulose reconstructions have also been used to capture high-resolution changes in the Asian Summer Monsoon system (Xu et al 2018).…”

Section: Tree Ring Cellulosementioning

confidence: 99%

Water isotopes, climate variability, and the hydrological cycle: recent advances and new frontiers

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Bailey

Conroy

et al. 2023

Environ. Res.: Climate

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The hydrologic cycle is a fundamental component of the climate system with critical societal and ecological relevance. Yet gaps persist in our understanding of water fluxes and their response to increased greenhouse gas forcing. The stable isotope ratios of oxygen and hydrogen in water provide a unique opportunity to evaluate hydrological processes and investigate their role in the variability of the climate system and its sensitivity to change. Water isotopes also form the basis of many paleoclimate proxies in a variety of archives, including ice cores, lake and marine sediments, corals, and speleothems. These records hold most of the available information about past hydrologic variability prior to instrumental observations. Water isotopes thus provide a ‘common currency’ that links paleoclimate archives to modern observations, allowing us to evaluate hydrologic processes and their effects on climate variability on a wide range of time and length scales. Building on previous literature summarizing advancements in water isotopic measurements and modeling and describe water isotopic applications for understanding hydrological processes, this topical review reflects on new insights about climate variability from isotopic studies. Our intention is to highlight new work and opportunities to enhance our understanding and predictive skill, rather than be exhaustive. We offer a set of recommendations to advance observational and model-based tools for climate research, and highlight opportunities to better constrain climate sensitivity and identify anthropogenically-driven hydrologic changes within the inherently noisy background of natural climate variability.

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Hydroclimate and ENSO Variability Recorded by Oxygen Isotopes From Tree Rings in the South American Altiplano

Abstract:  Tree-ring stable oxygen isotopes of Polylepis tarapacana record austral summer precipitation variability in the South American Altiplano. El Niño -Southern Oscillation is imprinted in the tree-ring oxygen isotopes with a stronger signal towards the north of the studied area.

Cited by 15 publications

References 64 publications

South American Summer Monsoon variability over the last millennium in paleoclimate records and isotope-enabled climate models

South American Summer Monsoon variability over the last millennium in paleoclimate records and isotope-enabled climate models

Hydroclimatic record from an Altiplano cushion peatland (24°S) indicates large-scale reorganisation of atmospheric circulation for the late Holocene

Water isotopes, climate variability, and the hydrological cycle: recent advances and new frontiers

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