20/06/2018 BLOG: Whether warm or cold, methane keeps leaking in the Arctic

Gas leakage on Vestnesa Ridge, has been occurring episodically over the last ca. 2 million years. Image: Alexey Portnov/CAGE

Methane has been leaking in the Arctic for millions of years, independent of warm or cold climate.

Blog post by: Jochen Knies, researcher NGU/CAGE

Recent observations of extensive methane release from the seafloor into the ocean and atmosphere cause concern as to whether increasing air temperatures across the Arctic are causing rapid melting of natural methane hydrates. Other studies, however, indicate that methane flares released in the Arctic today were created by processes that began way back in time – during the last Ice Age.

Newest research from the Center for Arctic Gas Hydrate, Climate and Environment (CAGE) shows that methane has been leaking in the Arctic for millions of years, independent of warm or cold climate. Methane has been forming in organic carbon rich sediments below the leakage spots off the coast of western Svalbard for a period of about 6 million years (since the late Miocene).  According to our models, methane flares occurred at the seafloor for the first time at around 2 million years ago; at the exact time when ice sheets started to expand in the Arctic.

The acceleration of leakage occurred when the ice sheets were big enough to erode and deliver huge amounts of sediments towards the continental slope.  Methane leakage was promoted due to formation of natural gas in organic-rich sediments under heavy loads of glacial sediments. Faults and fractures opened within the Earth’s crust as a consequence of growth and decay of the massive ice masses. This brought up the gases from deeper sediments higher up towards the seafloor. These gases then fueled the gas hydrate system off the Svalbard coast for the past 2 million years. It is, to this day, controlling the leakage of methane from the seabed. 

Source: Knies, J., Daszinnies, M., Plaza-Faverola, A., Chand, S., Sylta, Ø., Bünz, S., Johnson, J.E., Mattingsdal, R., Mienert, J. (2018): Modelling persistent methane seepage offshore western Svalbard since early Pleistocene. Marine and Petroleum Geology, 91, 800-811.

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