Rising Arctic Ocean temperatures cause gas hydrate destabilization and ocean acidification

• Main Authors: Rüpke, Lars, Biastoch, Arne, Treude, Tina, Riebesell, Ulf, Roth, Christina, Burwicz, Ewa, Park, Wonsun, Latif, Mojib, Böning, Claus W., Wallmann, Klaus, Madec, Gurvan
• Format: Book Part
• Language: English
• Published: HWU 2011
• Subjects: Arctic; Arctic Ocean; Global warming; Ocean acidification
• Online Access: https://oceanrep.geomar.de/id/eprint/13530/; https://oceanrep.geomar.de/id/eprint/13530/1/icgh2011Final00753.pdf

Formed under low temperature – high pressure conditions vast amounts of methane hydrates are considered to be locked up in sediments of continental margins including the Arctic shelf regions[1-3]. Because the Arctic has warmed considerably during the recent decades and because climate models predict accelerated warming if global greenhouse gas emissions continue to rise [3], it is debated whether shallow Arctic hydrate deposits could be destabilized in the near future[4, 5]. Methane (CH4), a greenhouse gas with a global warming potential about 25 times higher than CO2, could be released from the melting hydrates and enter the water column and atmosphere with uncertain consequences for the environment. In a recent study, we explored Arctic bottom water temperatures and their future evolution projected by a climate model [1]. Predicted bottom water warming is spatially inhomogeneous, with strongest impact on shallow regions affected by Atlantic inflow. Within the next 100 years, the warming affects 25% of shallow and mid- depth regions (water depth < 600 m) containing methane hydrates. We have quantified methane release from melting hydrates using transient models resolving the change in stability zone thickness. Due to slow heat diffusion rates, the change in stability zone thickness over the next 100 years is small and methane release limited. Even if these methane emissions were to reach the atmosphere, their climatic impact would be negligible as a climate model run confirms. However, the released methane, if dissolved into the water column, may contribute to ocean acidification and oxygen depletion in the water column.