Natasha Sekhon, Occidental College – Unlocking Ancient Water Signals Locked in the Geologic Record

The Academic Minute

On Occidental College Week: Hints to our climatic future could be hidden underground.

Natasha Sekhon, assistant professor in the department of geology, digs in for a look.

Dr. Natasha Sekhon has her training as a low-temperature geochemist and paleoclimatologist. She uses the geochemical signals preserved in speleothems (secondary cave deposits) and monitors modern cave systems to reconstruct periods of past climate change through the Quaternary and discern processes dictating modern cave systems. Dr. Sekhon’s research is multidisciplinary as she uses concepts from karst hydrology, speleothem sciences, climate dynamics and statistical modeling to investigate hydroclimate variability on seasonal to millennia time scales. She is interested in processes driving changes in global monsoon systems, El Nino Southern Oscillation, extreme hydroclimate conditions (floods and droughts) and periods of abrupt climate change. Dr. Sekhon earned her bachelor’s degree in Earth System Sciences from the University of California, Irvine. Dr. Sekhon received her doctorate from the University of Texas at Austin, following which she was a postdoctoral scholar at Brown University. She started as an Assistant Professor in Geology at Occidental College in January 2024.

Unlocking Ancient Water Signals Locked in the Geologic Record

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Tropical island nations are at the forefront of anthropogenic climate change impacts, from sea level rise to ocean acidification and severe changes in the hydroclimate system. With more than 7,000 archipelagos and its location in the Western Pacific Warm Pool, the Philippines is not a large contributor to greenhouse gas emissions, but still faces the brunt of climate impact, including changes in monsoon regimes and typhoon seasonality.

Ten percent of the total land surface in the Philippines is covered in karst landscapes—landscapes made up of sinkholes, caves, and springs—from underground river systems to karst hills. Cave formations such as stalagmites are valuable time capsules that store clues to ancient water climates, going back hundreds of thousands of years, and their trace element concentrations provide insight into previous periods of climate change.

In order to investigate the factors that have driven periods of hydroclimate variability, and therefore better constrain future climate projections for the region, our team of geologists is examining Philippine cave systems. Our work in multiple cave systems across a 10-degree latitudinal stretch focuses on understanding the processes driving shifts in the area’s rainfall over time. By studying changes in the oxygen isotopes of cave waters and stalagmite growth layers, our team is investigating changes in the strength of the summer and winter monsoons. Setting up continuous cave monitoring field sites provides an opportunity to calibrate our geochemical data with shifts in the hydroclimate. Because tropical island nations continue to be an understudied region in climate research, despite the increasing challenges they face, our studies, in partnership with local researchers and the caving community, will help fill this critical knowledge gap and provide much-needed data as we consider the future of climate impacts.

Read More:
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