Why the Arctic’s methane isn’t a catastrophic time bomb waiting to happen

There has been much concern over the possibility of a powerful positive feedback from melting arctic ice (caused by human warming of the arctic), in this case the rapid release of massive quantities of methane from below the surface into the atmosphere. Since methane is a very potent greenhouse gas, this would amplify the warming significantly and possibly cause dangerous, runaway climate change. This idea is supported by what I think is a minority view in the scientific literature, with many papers arguing against such alarm. Despite this, papers like this made waves in the media with claims of $60 trillion damages from the “methane time bomb”, as it has become known. Such claims are very unlikely, and were disputed hotly in the journal in which they were published. Furthermore, papers that do not even cite Whiteman et al. 2013 point to a less threatening situation. I will cover them here.

methanegraphic_feb2011_640

First is Near-surface permafrost degradation: How severe during the 21st century? This paper argues that a massive release of methane from melting arctic permafrost is dubious.

Second is Ancient Permafrost and a Future, Warmer Arctic. This paper reports that permafrost in subarctic Canada has survived interglacial periods which were warmer and lasted longer than the present one. This would imply that, at least to a certain degree of warming, much arctic permafrost will survive.

Third is Shrub expansion may reduce summer permafrost thaw in Siberian tundra. This paper argues that arctic shrub growth, which is expected with warming, may partially offset future permafrost thawing.

Fourth is Fluxes and fate of dissolved methane released at the seafloor at the landward limit of the gas hydrate stability zone offshore western Svalbard. This paper argues than most methane released from the seabed in Svalbard does not reach the atmosphere, preventing it from contributing to warming. There is a press release for the paper here.

Fifth is Extensive release of methane from Arctic seabed west of Svalbard during summer 2014 does not influence the atmosphere. This paper’s conclusions are similar to the fourth’s: that most methane being released from the Svalbard seabed does not reach the atmosphere. There is a press release for the paper here.

Sixth is No significant increase in long-term CH 4 emissions on North Slope of Alaska despite significant increase in air temperature. This paper argues that despite a significant increase in air temperature on the North Slope of Alaska, there has not been a significant increase in methane emissions. This means, they argue, that the arctic may not contribute significantly to methane emissions in the future if they continue at this trajectory. There is a press release for the paper here.

Seventh is Over-estimating climate warming-induced methane gas escape from the seafloor by neglecting multi-phase flow dynamics. This paper argues that by neglecting dynamics of seafloor methane, analyses can overestimate by orders of magnitude the amount of methane that will escape to the surface and provide a positive feedback.

So, in conclusion, though melting arctic ice may emit some methane into the atmosphere, the effect most likely will not be highly significant and virtually certainly not catastrophic.

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