Central Andean Paleoclimate
The tropical and central Andean highlands (>4,000 m above sea level) supply critical freshwater resources to the Amazon Basin, supporting about 90 million people. Due to the scarcity of historical weather data spatiotemporally, quantifying hydroclimate and environmental responses to anthropogenic climate change remains challenging. My Ph.D. dissertation focuses on quantifying local-scale and regional-scale hydroclimate and environmental changes in the tropical and central Andes over the past 2,700 years using geochemical proxies from lake sediments, peats, and soils, and computational approaches. I demonstrate that the magnitudes of the projected temperature changes due to anthropogenic forcings will exceed pre-Industrial temperature changes due to natural variability.
Dissertation Defense (October 2, 2023)
Summary Figure
Figure: Climate history of the Peruvian Andes from 700 BCE to 2100 CE. The x-axis reports time, while the y-axis shows the lake surface temperature anomaly relative to the 2019 CE level (horizontal dashed line). The temperature anomaly reconstruction from 700 BCE to 2019 CE (black line with a gray shading) is based on the glycerol dialkyl glycerol tetraethers. The pink and blue lines are projected lake surface temperature changes based on a 1-D lake energy balance model. The purple (yellow) bars at the top of the figure shows regional (local) hydroclimate history based on sedimentary leaf wax isotope analyses.
Techniques and skills Used
🌎 Collection of lake sediments, soil cores, plant samples, and water samples.
🌎 Bathymetric field survey and mapping using ArcGIS
🌎 Organic geochemistry techniques (e.g., organic lipid extraction & purification)
🌎 Bulk and isotope analysis of carbon and nitrogen via EA-IRMS
🌎 Leaf wax hydrogen and carbon isotope analysis via GC-C-IRMS
🌎 Glycerol dialkyl glycerol tetraether paleothermometry
🌎 Age-depth model reconstruction (Pb-210 and C-14)
🌎 Water hydrogen and oxygen isotope analysis
🌎 Elemental analysis via X-ray Fluorescence (XRF)
🌎 Fortran-based lake energy balance modeling with reanalysis and climate model simulation outputs.
🌎 Data analysis using python and R.
Moving Forward
I am eager to apply my paleoclimate expertise I developed during the Ph.D. training to explore how other regions/ecosystems respond to anthropogenic climate changes. I am particularly interested in the tropics since it is home to many climate phenomena, including the Inter-Tropical Convergence Zone (ITCZ), South American summer monsoon, El Nino-Southern Oscillation (ENSO), and South Asian monsoon, a sub-domain of Asian monsoon. I am also interested in the Arctic since temperature in this region is projected to increase two times faster than the global average.