Mid-to-Late Holocene Hydroclimate in the Southwest USA: Evidence from Lava Tube Ice with Dr. Onac

Thursday August 22

4:00 PM  –  5:00 PM

Thursday, August 22, 2024 at 4:00 p.m. MDT

Online Webinar

The southwestern United States has historically faced droughts and tough climate conditions, a situation predating the extensive effects of human-caused climate change. In Dr. Onac’s research, he focused on reconstructing the hydroclimate patterns of the Mid-to-Late Holocene period by analyzing the δ18O of perennial ice found in lava tubes located in the El Malpais National Monument, New Mexico. They recovered three ice cores (95 to 110 cm in length) from which subsamples were cut or drilled at 1-cm intervals. They, then, measured the δ18O isotopic composition of ice-melted water samples. Ice chronology relies on 14C-dated charcoal fragments and organic-rich layers, and U/Th dating of ice-melt water. From their observations and research, Dr. Onac  inferred that future climatic conditions in the southwest could lean towards aridity, especially if dominated by La Niña-like dry winters, potentially intensified by the negative phase of the Pacific Decadal Oscillation (PDO).

This webinar is suitable for lifelong learners from high school students to adults; this lesson is free.

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