Cafe Scientifique

Annapolis Café Scientifique

THURSDAY, July 30, 2026 talk: Taking a Closer Look at the Ocean’s Declining Oxygen, by Hernan Garcia. This will be the 100th talk since Tracy, Andy, Roz and Paul began hosting Annap.Cafe Sci!
Taking a Closer Look at the Ocean’s Declining Oxygen
Speaker: Hernan Garcia, PhD, Retired Oceanographer with NOAA’s National Environmental Satellite, Data, and Information Service (NESDIS).
About the Talk: Oxygen is critical to ocean health as it affects ecosystem composition, abundance, and distribution of marine microbes and animals. The ocean’s dissolved oxygen content has been declining by about 2% since at least the 1950s; a process termed ocean deoxygenation. This presentation provides a brief synthesis of observed O2 chemical changes and trends based on historical oceanographic data collected worldwide by many countries and institutions over the 1950 to 2023 time period.
About the Speaker: Hernan Garcia is a research chemical oceanographer with NOAA’s Centers for Environmental Information. He and NOAA colleagues developed the largest global ocean oceanographic database of observations to date. Hernan has always been interested in understanding global-scale ocean biochemical changes such as ocean deoxygenation and trends. He led the World Data Service for Oceanography and served as U.S. National Data Management coordinator for UNESCO. Hernan received his PhD at Oregon State University and conducted postdoctoral work at UCSD Scripps Institution of Oceanography before joining NOAA in 2001. He retired in July 2025 after 24 years with NOAA.
Observation-based trends (1960-2010) in dissolved oxygen change in the ocean in the upper 1200 meters (0.75 mi). Most of the open ocean shows deoxygenation in varying degrees of magnitude. Source: Schmidtko et al. Decline in global oceanic oxygen content during the past five decades. Nature 542, 335–339 (2017). https://doi.org/10.1038/nature21399

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If you can’t come in person, please join us on Zoom with Host Roz Kleffman.
https://us02web.zoom.us/j/87848406572?pwd=VVVFOVNwNFdtN1VDVDA3Sk5yc0VLdz09
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