Past and present precipitation variability across Mesoamerica: the implications for changing global climate in regions of restricted water resources
I am using the hydrogen isotope composition of leaf wax biomarkers to determine how precipitation patterns are recorded in lake sediment core-top samples across Mesoamerica. Previous studies have demonstrated an offset between the hydrogen isotope composition of precipitation and that of leaf waxes due to biological processes and other environmental factors, which vary regionally (Sachse et al., 2012). While a precise calibration between leaf wax and rainfall hydrogen isotopes is lacking in Mesoamerica, preliminary data from this region suggests a strong likelihood of success (Douglas et al., 2012). After I quantify the patterns in biomarker hydrogen isotopes and relate them to modern climate and environmental trends, I will apply this calibration to a lake sediment paleorecord from an arid site in western Mexico, Laguna de Juanacatlán.
Laguna de Juanacatlán is located in the Mexican state of Jalisco, a notably dry region receiving greater than 80% of its annual precipitation from the southern edge of the summer North American Monsoon (Metcalfe et al., 2012). The lake sediment record from Juanacatlán spans the past 4,000 years according to radiocarbon dating, recording important global climate shifts including the Medieval Climate Anomaly (800-1200/1300 CE – characterized by variable but generally warmer conditions globally) and the Little Ice Age (1350-1850 CE - a period of worldwide cooling). Samples have been taken from the sediment core from Laguna de Juanacatlán at high temporal resolution for a detailed analysis of short-term rainfall variability due to these documented global climate changes. Lake sediment fatty acids are extracted, isolated, and analyzed to identify and quantify the individual leaf waxes and their hydrogen isotope compositions.
Once the response of regional precipitation to changing global temperatures is known, climate modelers can better predict the effects of anticipated climate change on rainfall patterns and provide policy makers with a better understanding of the influence of these impacts on natural ecosystems, agriculture, and human infrastructure. My study will help to develop a stronger understanding of how climate change in this water-restricted area is likely to impact important water resources in Mesoamerica, ultimately assisting to inform local resource management, regional planning, and climate change education.
Sachse et al (2012) Annual Review of Earth and Planetary Sciences 40:221-249.
Douglas et al (2012) Geochim. Cosmochim. Acta 97:24-45.
Metcalfe et al (2012) The Holocene 20(8):1195-1206.
Laguna de Juanacatlán is located in the Mexican state of Jalisco, a notably dry region receiving greater than 80% of its annual precipitation from the southern edge of the summer North American Monsoon (Metcalfe et al., 2012). The lake sediment record from Juanacatlán spans the past 4,000 years according to radiocarbon dating, recording important global climate shifts including the Medieval Climate Anomaly (800-1200/1300 CE – characterized by variable but generally warmer conditions globally) and the Little Ice Age (1350-1850 CE - a period of worldwide cooling). Samples have been taken from the sediment core from Laguna de Juanacatlán at high temporal resolution for a detailed analysis of short-term rainfall variability due to these documented global climate changes. Lake sediment fatty acids are extracted, isolated, and analyzed to identify and quantify the individual leaf waxes and their hydrogen isotope compositions.
Once the response of regional precipitation to changing global temperatures is known, climate modelers can better predict the effects of anticipated climate change on rainfall patterns and provide policy makers with a better understanding of the influence of these impacts on natural ecosystems, agriculture, and human infrastructure. My study will help to develop a stronger understanding of how climate change in this water-restricted area is likely to impact important water resources in Mesoamerica, ultimately assisting to inform local resource management, regional planning, and climate change education.
Sachse et al (2012) Annual Review of Earth and Planetary Sciences 40:221-249.
Douglas et al (2012) Geochim. Cosmochim. Acta 97:24-45.
Metcalfe et al (2012) The Holocene 20(8):1195-1206.