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Comment by seraphsf | Hacker News Reader

Summary from the excellent, erudite Twitter thread (https://mobile.twitter.com/DrTELS/status/1151868725336952832) cited in the article:

Why should we be worried? Peat shouldn't be available to burn. It only burns when it has been disturbed by some significant environmental change (e.g. drainage/drought). Siberian peatlands should be moist/frozen through summer, but this year's heatwave has dried them out.

Peat fires in the Arctic are part of a number of positive feedback mechanisms in the climate system. They release old carbon in the form of CO2 & methane emissions, exacerbating global heating, and they leave behind a dark charred surface leading to localised heating.

Some tentative conclusions:

- at least some of these fires were ignited by lightning

- ignition made far more likely by heatwave

- fires are burning peat soils

- this is the symptom of a sick Arctic

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This kind of Question might be unpopular but do those wildfires have any quantitative relevance in accelerating global warming? Or ask differently how much of Siberia would have to burn to make any noticeable difference In the CO2 balance

These fires substantially accelerate the melting of the permafrost, both by the primary heat of combustion, but also by secondary effects like soot. Permafrost stores about 1500 Gigatons of carbon. Humanity has released about 650 Gigatons of carbon in total so far.

Will all those 1500 Gigatons be released when the permafrost melts?

I wouldn't think so, simply being melted doesn't mean it's released, but the decay processes triggered by the melting and now apparently wildfires will start eating into it. It's likely very difficult to predict what proportion would eventually be released and over what time frame.

However it wouldn't take much in the grand scheme of things to negate any reductions in CO2 release we manage to make as a civilization, more or less maintaining the total current CO2 release levels indefinitely. That's a pretty worrying scenario by itself.

The much bigger problem relating to this thawing permafrost is the fact that as it thaws it then starts to decompose.

That decomposition not only produces carbon dioxide but also methane and methane is a much worse greenhouse gas than carbon dioxide.

So yes, this thawing permafrost provides several ways to help accelerate global warming.

Wouldn’t it also provide fertile ground for trees to grow and absorb much more CO2 in total?

That's kinda like noticing your house is on fire and thinking it's been a while since you had toasted marshmallows.

Yes. The impact is so significant that scientists refer to as the "carbon timebomb".

Thanks for a good twitter thread. Later on that thread has some interesting statistics about the estimated power output of these fires and how much it is over the average: https://mobile.twitter.com/m_parrington/status/1151905483625...

Scary stuff, I hope this is not kicking some feedback loops in to action. -edit: typo

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