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This article has gotten some attention lately, implying that a large release of methane from the Arctic Ocean is imminent. Is this as scary as the headline suggests or is this mostly some hot air? A thread. 1/9 https://www.theguardian.com/science/2020/oct/27/sleeping-giant-arctic-methane-deposits-starting-to-release-scientists-find
First: a newly discovered source is not the same as a changing source. It’s pure speculation that these hydrates destabilized recently. Seeps like these are highly localized and could have been missed by previous cruises – if the area was surveyed before at all. 2/9
Even if these seeps change, we know from well-studied seeps off the coast of Svalbard – located at a similar depth – that methane quickly dissolves into the ocean when bubbles rise upwards through the water column. The atmospheric impact is negligable. 3/9 https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2016GL068999
Fun fact, those seeps off the coast of Svalbard have been active for at least 3000 years and the local ocean takes up enough CO2 to compensate for the warming potential of methane. That may be true for these new seeps as well. 4/9
https://science.sciencemag.org/content/343/6168/284.abstract
https://www.pnas.org/content/114/21/5355.short
https://science.sciencemag.org/content/343/6168/284.abstract
https://www.pnas.org/content/114/21/5355.short
What about the shallower arctic shelves? Several independent studies show that the same group featured in the Guardian article overestimated those sources by roughly a factor of five. 5/9
https://acp.copernicus.org/articles/16/4147/2016/
https://advances.sciencemag.org/content/6/5/eaay7934
https://www.sciencedirect.com/science/article/pii/S1873965220300803
https://acp.copernicus.org/articles/16/4147/2016/
https://advances.sciencemag.org/content/6/5/eaay7934
https://www.sciencedirect.com/science/article/pii/S1873965220300803
Also, modeling studies show that hydrates in the Arctic are slow to respond to climate change. Relevant timescales are centuries up to a millennium, which makes it unlikely that ‘a sleeping giant’ has been awoken already. 6/9
https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014GB005011
https://bg.copernicus.org/articles/12/2953/2015/
https://agupubs.onlinelibrary.wiley.com/doi/10.1002/2014GB005011
https://bg.copernicus.org/articles/12/2953/2015/
Rather than gas hydrates deep down in the ocean, climate change is much more likely to increase terrestrial sources. Permafrost thaw can release both methane and CO2 into the atmosphere, accelerating climate change. 7/9
https://www.nature.com/articles/nature14338
https://www.nature.com/articles/s41561-019-0526-0
https://www.nature.com/articles/nature14338
https://www.nature.com/articles/s41561-019-0526-0
So what to do? Natural emissions can’t be controlled, but we can reduce the risk of crossing tipping points in the climate system by reducing anthropogenic emissions. With present day technology we can compensate for arctic methane release: 8/9 https://www.nature.com/articles/s41598-018-37719-9
To conclude: recent studies show that the Arctic Ocean releases <5 Tg CH4/yr. No more than 1% of global methane sources. Our own anthropogenic emissions are ~70 times larger. Perhaps we should worry more about the problem we can control rather than hypothetical sea monsters? 9/9
