Climatic variability and human impact during the last 2000 years in western Mesoamerica: evidences of late Classic and Little Ice Age drought events (original) (raw)
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Climate of the Past, 2015
We present results of analysis of biological (diatoms and ostracodes) and non-biological (Ti, Ca / Ti, total inorganic carbon, magnetic susceptibility) variables from an 8.8 m long, high-resolution (~ 20 yr sample<sup>−1</sup>) laminated sediment sequence from Lake Santa María del Oro (SMO), western Mexico. This lake lies at a sensitive location between the dry climates of northern Mexico, under the influence of the North Pacific subtropical high-pressure cell and the moister climates of central Mexico, under the influence of the seasonal migration of the intertropical convergence zone and the North American monsoon (NAM). The sequence covers the last 2000 years and provides evidence of two periods of human impact in the catchment, shown by increases in the diatom <i>Achnanthidium minutissimum</i>. The first from AD 100 to 400 (Early Classic) is related to the shaft and chamber tombs cultural tradition in western Mexico, and the second is related to Post-Clas...
Deciphering recent climate change in central Mexican lake records
Climatic Change, 2007
Central Mexico contains a large number of lake basins offering opportunities for climatic reconstruction. The area has, however, also been the focus for human settlement since the time of the earliest occupation of the Americas, as well as being subject to tectonic and volcanic activity. A number of methodological issues arise including the susceptibility of common palaeoecological proxies (pollen, diatoms) to multiple forcing factors and problems of obtaining reliable chronologies. Published lake records indicate that the last 1,500 years have been marked by strong climatic variability, superimposed on continuing high levels of anthropogenic impact. Dry conditions, probably the driest of the Holocene, are recorded over the period 1400 to 800 14 C yr BP (ca. AD 700-1200). Climatic change over the last 1,000 years is not well represented, but there are indications of drier conditions corresponding to the 'Little Ice Age' of mid-to high latitudes. A range of mechanisms (e.g. solar cycles, ENSO variability) have been proposed to explain climatic variability over the last 1,500 years, but current lake records are inadequate to test these. The developing dendroclimatology for the Mexican highlands and the rich historical archives of the Hispanic period (from AD 1521) offer new opportunities and challenges to palaeolimnologists.
The Holocene history of a tropical high-altitude lake in central Mexico
The Holocene, 2020
High-altitude lakes are sensitive to modern and past climate changes. Given their low-water temperatures, alkalinity, and nutrient levels, small climatic differences can strongly affect their water chemistry, and/or biodiversity. In central Mexico, there are only two high-altitude lakes, and both are within the crater of the Nevado de Toluca volcano. Here, we present a paleolimnological record from one of these lakes: La Luna. Previous paleoenvironmental work showed that it was sensitive to the Little Ice Age (LIA) cooling. Our results show that sediment accumulation began ~6900 to 6100 cal. yr BP under periglacial conditions and that lake conditions were established ~6000 cal. yr BP. One tephra layer was dated to ~5600 cal. yr BP, with no evidence of more recent volcanic activity. The early stages of this lake (6000–4700 cal. yr BP) contained Cladocera and diatom assemblages with different species composition than modern assemblages. This early stage community structure was related...
Quaternary Science Reviews, 2010
This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from two maar crater lakes in the Valle de Santiago of Guanajuato, Mexico: Hoya San Nicolá s and Hoya Rincon de Parangueo. Sediment cores from the two sites have basal dates of ca 11,600 and 9600 cal yr BP, respectively. The San Nicolá s results show that the lake desiccated several times during the Holocene, and this resulted in the selective destruction of the less resistant pollen types. A comparative analysis of data from both sites indicates that during the earliest Holocene (ca 11,600-9000 cal yr BP) there were short term oscillations of wetter and drier climate; during the early Holocene (ca 9000-5700 cal yr BP) it was on average wetter; during the middle Holocene (ca 5700-3800 cal yr BP) drier; and during the middle to late Holocene (ca 3800-2200 cal yr BP) wetter. Increasing human disturbance during the late Holocene of environment obscures the climatic record. Agricultural activities in the area began as early as ca 5700 cal yr BP and intensified around 2400 cal yr BP.
A 6,000 year record of environmental change from the eastern Pacific margin of central Mexico
Quaternary Science Reviews, 2018
The transition from the mid-to late-Holocene in MesoAmerica saw increasing complexity in spatial patterns of change. Records from the western part of the region are sparse, with lacustrine sequences affected by long term anthropogenic disturbance or lacking chronological resolution. Here, we present a continuous palaeoecological and geochemical record from Laguna de Juanacatlán, a remote lake in the mountains of the western TMVB. Diatom assemblages, XRF scanning data and bulk organic geochemistry from a well-dated, 7.25-m laminated sequence were combined with summary pollen data from a 9-m partially laminated core to provide a continuous record of catchment and lake ecosystem changes over the last c. 6,000 years. Relatively humid conditions prevailed prior to c. 5.1 cal ka, which supported dense oak-pine forest cover around a deep, stratified lake. A trend towards drier conditions began c. 5.1 cal ka, intensifying after 4.0 cal ka, consistent with weakening of the North American Monsoon. Between 3.0 and 1.2 cal ka, lower lake levels and variable catchment runoff are consistent with increasing ENSO influence observed in the Late Holocene in the neotropics. From 1.2 to 0.9 cal ka, a marked change to catchment stability and more intense stratification reflected drier conditions and / or reduced rainfall variability and possibly warmer temperatures. After 0.9 cal ka, conditions were wetter, with an increase in catchment disturbance associated with the combined effects of climate and human activity. In recent decades, the lake ecosystem has changed markedly, possibly in response to recent climate change as well as local catchment dynamics.
2016
During the Holocene, most of the climatic variability in the tropics has manifested through changes in the precipitation regime. Although there is relatively a large amount of information on this climatic variability from the lowlands during this time period, little is known regarding the environmental variability in the middle elevations. Here we present evidence of environmental change from a lacustrine sedimentary record recovered from Lake Lacandón, a small shallow water body located in the middle elevations of Chiapas, Mexico. Through analyses of cladoceran assemblages and chemical properties of the sediments (concentrations of C, Ca, N, Rb, Sr, Ti, and Zr), we aimed to reconstruct local and regional environmental conditions during the last 4,000 years. Our results show a highly dynamic cladoceran community apparently associated with changes in the size of the lake, which although variable has been enlarging through the last 4,000 years. Geochemical evidence also suggests high variability in moisture availability overimposed on a general trend towards drier conditions. Whereas the growing lake size seems associated with decreasing insolation seasonality, the trend to drier regional climates corresponds to the well-known southward displacement of the Intertropical Convergence Zone through the Holocene. Although the regional climate has been deteriorating, the enlarging lake suggests a decreasing water deficit though time. This pattern is probably a result of increasing insolation during the dry season, causing advection of marine moisture that precipitates because of the steep elevation gradient. Our results highlight the intricate nature of the millennial scale environmental variability, and the potential role of the middle elevations for sheltering biodiversity through times of environmental hardship. RESUMEN Durante el Holoceno la mayor parte de la variabilidad climática en los trópicos se manifestó a través de cambios en los regímenes de precipi-tación. En este sentido, existe una cantidad de información relativamente extensa con respecto a la variabilidad climática en las tierras bajas, mientras poco se conoce en relación a la variabilidad ambiental de las elevaciones medias. En este trabajo presentamos evidencia de cambios ambientales derivada de una secuencia sedimentaria recuperada en el Lago Lacandón, un cuerpo de agua somero y pequeño ubicado en las elevaciones medias del Estado de Chiapas, México. Mediante el análisis de algunas propiedades químicas de los sedimentos (concentraciones de C, Ca, N, Rb, Sr, Ti, y Zr) y los ensambles de cladóceros contenidos por los mismos, abordamos la reconstrucción de las condiciones ambientales locales y regionales a través de los últimos 4,000 años. Los resultados mos-traron una comunidad de cladóceros altamente dinámica en el tiempo que ha estado aparentemente asociada con el tamaño del lago. Los cladóceros muestran que, aunque variable, el tamaño del cuerpo de agua ha mostra-do una tendencia creciente a través del tiempo. La evidencia geoquímica también muestra alta variabilidad en la disponibilidad de humedad
Inland Waters, 2013
We investigated late Holocene (2000 YBP to present) drought in northern New Mexico, USA, using diatom valves sampled from a lake sediment core. Diatoms were analyzed with a combination of multivariate ordination and time series analysis to identify significant changes in community dynamics and corresponding significant bifurcations between periods of increased and decreased precipitation. This diatom-inferred precipitation regime was statistically corroborated against an independently derived tree ring record of precipitation in northern New Mexico. Also, both the tree ring and diatom records were tested for concordance with indirect radiocarbon solar intensity data and were both significantly cross-correlated with solar intensity. Periods of drought aligned with periods of decreased solar intensity during ~1400-1000 and ~600-200 YBP; periods of increased solar activity aligned with periods of increased precipitation during ~1000-600 YBP and ~200 YBP to present day. These results suggest that longer-term drought regimes in northern New Mexico may have been modulated by solar activity.
Quaternary Science Reviews Volume 282, 2022
The importance of climate change, specifically drought, across the Maya region in the northern Neotropics, remains a topic of lively debate. Part of this discussion hinges on the coherency of response to climatic variability across different archives and proxies. In this paper we present a 6600-year palaeolimnological record from Yaal Chac, a carbonate lake (known locally as a cenote) in the northern lowlands of the Yucatan Peninsula, < 2 km from the location of the previously published Aguada X'Caamal record. The Yaal Chac sequence has been analysed for loss-on-ignition (LOI), stable isotopes (d 18 O, d 13 C) and elemental analysis using mXRF, complemented by some mineralogical, charcoal and pigment data. Mid Holocene sediments, predating evidence of human impact, are carbonate dominated and finely laminated. d 18 O values are positive (>2‰), but show no covariation with d 13 C. A major transition occurs at ca. 4360 cal yr BP, with a change to generally more organic sediments and increased variability in all proxies. Although direct evidence for anthropogenic activity in the Yaal Chac catchment is limited, it seems feasible that human impact was affecting the system. Comparison with other records from the Northern Maya lowlands and the wider region shows little coherence in the mid Holocene, when Yaal Chac seems to have been quite stable, but possibly responsive to increased climatic seasonality, driving the production of seasonal laminae. In the late Holocene, when the climate was generally more variable, there is more coherence between Yaal Chac and other regional records, including the so called Pan Caribbean Dry Period (3500e2500 cal yr BP) and the droughts of the late Pre-Classic period (1800e1600 cal yr BP). The Yaal Chac record shows no evidence of drought at the time of either the Maya 'hiatus' or the Maya 'collapse' of the Terminal Classic, but does record drying from the 14th to 19th centuries CE, in keeping with other proxy and historical records. This new record from Yaal Chac highlights the spatial variability of responses to climate forcings and the importance of recognising individual system sensitivity.
Late Pleistocene and Holocene Paleoenvironments of Chalco Lake, Central Mexico
Quaternary Research, 1993
In order to establish paleoenvironmental conditions during the late Quaternary, four cores from the Basin of Mexico (central Mexico) were drilled in Chalco Lake, located in the southeastern part of the basin. The upper 8 m of two parallel cores were studied, using paleomagnetic, loss-on-ignition, pollen, and diatom analyses. Based on 11 14C ages, the analyzed record spans the last 19,000 14C yr B.P. Volcanic activity has affected microfossil abundances, both directly and indirectly, resulting in absence or reduction of pollen and diatom assemblages. Important volcanic activity took place between 19,000 and 15,000 yr B.P. when the lake was a shallow alkaline marsh and an increase of grassland pollen suggests a dry, cold climate. During this interval, abrupt environmental changes with increasing moisture occurred. From 15,000 until 12,500 yr B.P. the lake level increased and the pollen indicates wetter conditions. The highest lake level is registered from 12,500 to ca. 9000 yr B.P. Th...