Extensive Methane Venting to the Atmosphere from Sediments of the East Siberian Arctic Shelf

Abstract

Remobilization to the atmosphere of only a small fraction of the methane held in East Siberian Arctic Shelf (ESAS) sediments could trigger abrupt climate warming, yet it is believed that sub-sea permafrost acts as a lid to keep this shallow methane reservoir in place. Here, we show that more than 5000 at-sea observations of dissolved methane demonstrates that greater than 80% of ESAS bottom waters and greater than 50% of surface waters are supersaturated with methane regarding to the atmosphere. The current atmospheric venting flux, which is composed of a diffusive component and a gradual ebullition component, is on par with previous estimates of methane venting from the entire World Ocean. Leakage of methane through shallow ESAS waters needs to be considered in interactions between the biogeosphere and a warming Arctic climate.

Communal visual histories to detect environmental change in northern areas: Examples of emerging North American and Eurasian practices

“…The sites of melting permafrost recorded by the herders have been instrumental in widening the scope and extent of the phenomena and its study. Melting permafrost, with its methane releases, both on land (Walter et al 2006) and on the continental shelf (Shaktova et al 2010) of northeastern Siberia, constitute a process, which has global significance, too, due to the amounts of greenhouse gases being released. Scientists have not yet recorded all of the sites of change and here the efforts of the herders can assist them with the detection of terrestrial change.…”

“…This has profound consequences for the climate (Shaktova et al 2010), flora, fauna, and human societies of the region (Kumpula et al 2010;Arctic Council 2013;Fidel et al 2014). Coinciding with this realization are the various efforts across multiple academic disciplines, cultures, languages, and sectoral approaches in the North to address and understand the new conditions of the Arctic-much of the region is still underexplored, and simultaneously the current change underway affects and produces new contexts and conditions.…”

Arctic Climate Tipping Points

“…This is part of the East Siberian Arctic Shelf, which is a large area (2.1 million km 2 ) of submerged permafrost and peatland that was flooded during the early Holocene (Shakhova et al 2010). Much of the water there is supersaturated with methane coming out of the submerged sediments and the region is venting *8 TgC-CH 4 year -1 to the atmosphere (Shakhova et al 2010).…”

“…This is part of the East Siberian Arctic Shelf, which is a large area (2.1 million km 2 ) of submerged permafrost and peatland that was flooded during the early Holocene (Shakhova et al 2010). Much of the water there is supersaturated with methane coming out of the submerged sediments and the region is venting *8 TgC-CH 4 year -1 to the atmosphere (Shakhova et al 2010). This is only around 2% of the global methane source to the atmosphere, but if the intrusion of warm Atlantic waters increases this could further destabilise the submerged permafrost (Dmitrenko et al 2010).…”

“…Bubbles associated with the melting of methane may trigger submarine landslides (Kayen and Lee 1991), and this raised concern that the destabilization of methane hydrates could result in abrupt and massive releases of methane into the atmosphere. The most vulnerable methane hydrate deposits are shallow ones, such as those found in the Arctic (Reagan and Moridis 2007), including under the East Siberian Arctic Shelf (Shakhova et al 2010). However, estimates that this region could produce an abrupt release of *12 times the current atmospheric methane burden (Shakhova et al 2008), are completely at odds with state-of-the-art models (Archer et al 2009) and palaeo-climatic evidence (Archer 2007).…”