Imaging the Arctic Seafloor to Examine Escape Routes of the Greenhouse Gas Methane

Vast amounts of the greenhouse gas methane are stored under the ocean floor as ice-like, crystalline compounds called hydrates. These naturally occurring structures form under high pressure and in low temperatures, when water molecules encage and stabilize gases. These hydrocarbon gases originate from thermogenic/abiogenic sources deep below the ocean floor and/or from biogenic shallow sources. The Arctic holds vast undiscovered reserves of hydrates with mixtures of thermogenic and biogenic methane. The last deglaciation some 16,000 years ago and today’s ocean warming cause them to melt and release methane from—for example— fault networks and craters of the ocean floor. The most dominant forces to have ever affected large regions of the Arctic are the growth and collapse of the ice sheets in the northern hemisphere and the recent climate change. Obviously, we cannot observe firsthand the natural world of the prehistoric past. However, we do have high-resolution 3D/4D seismic, as well as seafloor, observations, and well-constrained numerical modelling. Using this technology, we have been able to see into sub-seabed fluid migration and seabed-fluid expulsion systems. Deep hydrocarbon reservoirs exist today beneath the pressures of the ice sheets in Greenland and Antarctica. Signs of instability and fluid migration may become commonplace under scenarios of fast ice retreat. Presenter Bio Jurgen Mienert is a Professor for Applied Geophysics and Arctic Marine Geology at UiT—The Arctic University of Norway, Tromsø since 1998. Jürgen chaired the European Ocean Margin Research Consortium (OMARC) from 2003–2006 with a focus to better understand the response of European margin systems to climate change. He led the Department of Geology from 2008–2012, before his team received an award for building a Centre of Excellence by the Norwegian Research Council in 2012. He was Director of this Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) from 2013-2017. His research focuses on understanding the rate at which rising ocean temperatures can destabilize shallow, Arctic methane hydrate reservoirs leading to geohazards and methane release to the ocean and atmosphere. Jürgen received his Ph.D. in geoscience from the Christian-Albrechts University (CAU) at Kiel, Germany (1985) before he was awarded a post-doctoral position at Woods Hole Oceanographic Institution, USA (1985–1988) and returned to Kiel in 1988 to join the newly established Centre for Marine Geosciences—GEOMAR—at the CAU, Kiel. His collaboration with teams from Russia, USA, Canada, and Europe on polar shelf and slope environments facilitated active cooperation among hydrocarbon companies, technology providers, and Arctic research groups. His many sea expeditions included contributions to the Norwegian deep-water gas field “Ormen Lange” investigation, dives with Russian submersibles MIR from RV Keldysh (1998) to the deep ocean floor at the giant submarine “Storegga slide” on the Mid-Norwegian Margin and to natural gas release sites along the Barents-Svalbard margins, which provided an indispensable guide for methane hydrate studies. Jürgen has authored and co-authored more than 200 papers in peer-reviewed journals.

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