I think the prevailing opinion remains that it is a very important threat in the long run, but that there is no realistic mechanism proposed for an abrupt release in the space of a few decades or a century.
Since then, however, there appears to be more and more discussion of methane release in the Arctic. There’s a recent post by Jason Box called Is the climate dragon awakening? This post highlights that there is evidence that methane is reaching ocean surface, rather then being converted into the less greenhouse CO2 before getting to the surface. There’s also the recent discoveries of a few craters in Siberia. It’s thought that these are caused by an accumulation of methane that eventually bursts to the surface through the thawing permafrost.
However, my understanding is that even though there’s been more discussion of Arctic methane release, the evidence for an abrupt release of methane in the next decades or century is still low. I also saw some tweets from Gavin Schmidt that seemed to confirm this general view. Having said that, that doesn’t mean that what’s happening in the Arctic isn’t cause for some concern. I’ll end this post with an interesting video that I watched this morning. It’s a little long, but is divided into 5 chapters. Although it does cover the abrupt release of methane, the more robust results are that the Arctic is warming faster than the rest of the globe and could warm by between 6 and 16 degrees by 2100, if we follow a high-emission pathway. The permafrost is already thawing, contributing to greenhouse gas emissions and this feedback could increase atmospheric concentrations by between 50 and 250 ppm by 2100, even without any abrupt release of methane. Additionally, that the Arctic is warming faster than the rest of the globe will change atmospheric temperature gradients and will have to influence global weather patterns.
So, even though there may not have to worry about some kind of catastrophic Arctic event, that doesn’t mean that what’s happen in the Arctic isn’t cause for concern. I know I try not to discuss policy too much on this blog, but I would argue that a rapid warming of the Arctic that will clearly influence weather patterns elsewhere on the globe – in ways that may be hard to predict – is something that we should be avoiding if we can. I don’t know how else to do this other than to reduce atmospheric CO2 concentrations (or maybe, more realistically, prevent them from reaching levels much higher than today). Maybe we can find some way to do this without reducing our use of fossil fuels, but an obvious way would be to focus on finding ways to provide energy that doesn’t increase atmospheric CO2 levels to the point where changes to the Arctic are so substantial that the influences will be felt across the globe.