1,10,3,5,6- 1Department of Geology, Occidental College, Los Angeles, USA (sekhon@oxy.edu)
- 2Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, USA
- 3Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, USA
- 4Department of Atmospheric, Oceanic & Earth Sciences, George Mason University, Fairfax, USA
- 5Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, USA
- 6Institute at Brown for Environment and Society, Brown University, Providence, USA
- 7Laboratory of Tree-Ring Research, University of Arizona, Tucson, USA
- 8National Institute of Geological Sciences, University of the Philippines, Diliman, Quezon City, Philippines
- 9Palawan Speleo Inc., Puerto Princesa City, Palawan, Philippines
- 10Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, USA
Understanding past climate trends is crucial for projecting future hydroclimate changes, especially in the context of rapid anthropogenic climate change. Here, we focus on reconstructing hydroclimate variability during periods of past climate change from the tropics , which remain underrepresented in climate variability studies despite their heightened vulnerability to ongoing climatic shifts.
Here, we investigate ẟ18O, ẟ13C, and trace elements (Mg/Ca, Ba/Ca, Sr/Ca) in multiple speleothem samples across the Philippines. Speleothem sample, BH-1, was collected from Hinagdanan Cave (9.6253° N, 123.8009° E) and grew between 26-51 kyrs B.P. with an average growth rate of 8.12 μm/yr. Another speleothem sample PPUR-GP-3 collected from the Puerto Princesa Subterranean River National Park (10.1926° N, 118.9266° E) grew between 4-48 kyrs B.P. with a hiatus between 16,243 ± 146 years B.P. to 35,300 ± 538 years (±2𝜎). Collectively, speleothem growth encompasses critical periods of past climate change such as Heinrich Events 1 through 5, the Younger Dryas, and the last deglaciation. Modern climatology data and ongoing cave monitoring data suggests that Hinagdanan Cave and Princesa Subterranean River National Park recharges from summer precipitation.
Initial geochemical findings indicate fluctuating trace element data suggesting drying trends over time, characterized by an increase in Mg/Ca and a decrease in Sr/Ca in PPUR-GP3. Change-point analysis conducted on the ẟ18O record in BH-1 reveals that Heinrich Event 3 in the Philippines experienced drying conditions. The drying is in alignment with ẟ18O trends reflected in Borneo stacked speleothem records. Further investigation of BH-1 and PPUR-GP3 trace elements and stable isotopes will disentangle regional (ẟ18O amount effect, moisture source) versus local (prior calcite precipitation) hydroclimate variability. Finally, we will compare our new geochemical results with existing isotope-enabled climate model simulations (iTRACE) to discern potential climate drivers that modulate IPWP hydroclimate during key climate events.
How to cite: Sekhon, N., Senan, S., Hart, M., Kong-Johnson, C., Yambing, J. O., Du, X., Vega, M. G., Belanger, B., Geronia, M., Jaladoni, S., David, C. P., Oster, J., McGee, D., and Ibarra, D.: Reconstructing Tropical Hydroclimate Variability using Speleothems from the Philippines During Abrupt Climate Events, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14602, https://doi.org/10.5194/egusphere-egu26-14602, 2026.
