Current Research in EEPS: Dr. Yige Zhang, Texas A&M University
Methane hydrate dissociation-driven climate change: Reality or fiction?
Methane hydrate dissociation has long been considered as a mechanism for global carbon cycle perturbations, climate change and even mass extinctions in Earth’s history. However, direct evidence of hydrate destabilization and methane release that coincides with such events is scarce. Also, modern observations and modeling show that the marine hydrate reservoir is smaller than originally thought, and methane released from hydrates typically dissipates into sweater, rarely making its way to the atmosphere.
We use diagnostic lipid biomarkers directly linked to methanotrophic microorganisms to track the dissociation of gas hydrates in Earth’s Cenozoic history. These biomarkers are extremely sensitive, quantitative, and easy to measure. We show biomarker and compound-specific isotope evidence of methane release and oxidation across the Oligocene – Miocene Boundary (~23 Ma) and during the Paleocene-Eocene Thermal Maximum (~56 Ma). These studies suggest that aerobic oxidation of methane in seawater which consumes oxygen and acidifies the ocean is a key process that drives climate and biogeochemistry changes.