[rale00]

Methane is fairly short-lived in the atmosphere, at only 12 years, so it probably wouldn't be particularly effective at terraforming mars. Perfluorocarbons or sulfur hexafluoride can stick around for thousands of years, so they would probably be a better place to start.

[ncmncm]

Current SF6 level (four orders of magnitude more heat-trapping than CO2, by weight) accounts for 10% of heat forcing. How the heck do we get that stuff out of the atmosphere?

There is a replacement, now, for SF6, for use in power stations and wind turbines. Now the SF6 in use needs to be pumped out and disposed of safely, and SF6 actually banned. And, we have to persuade China to replace theirs too.

[tgsovlerkhgsel]

> Current SF6 level (...) accounts for 10% of heat forcing.

Source? This does not match what https://en.wikipedia.org/wiki/IPCC_list_of_greenhouse_gases says.

In my naive mind, Methane seems like the it could be a good candidate for removal from atmosphere: If you could just get it to react with oxygen, it turns into water and the much less harmful CO2, so you don't have to sequester anything, and the reaction is exothermic i.e. it already "wants to happen"... we would "only" need an effective yet cheap catalyst to make it happen at low temperatures.

[ncmncm]

https://en.wikipedia.org/wiki/Sulfur_hexafluoride#Greenhouse... :

"the collective contribution of [SF6] and similar man-made halogenated gases has reached about 10 percent as of year 2020". But reading more closely, it seems the SF6 by itself is much less. The rest, I guess, must be CFCs and HFCs.

[marcosdumay]

If you follow the citation, you get to this graph:

https://gml.noaa.gov/aggi/aggi.fig3.png

Those 10% are almost all CFC, then the next largest component is HCFCs and then HFCs, where SF6 is included. On the graph subtitle it's explained that SF6 is about 13% of the HFCs component.

Anyway, that's a large change from the last data I've found.

[ordu]

Do you suggest releasing a catalyst into atmosphere? It may be dangerous, people tend to release methane, kids sometimes injure themselves by "catalysing" reaction of methane with oxygen by a flame source just for fun of watching flame farts. It would be unfortunate if these flame farts happened spontaneously as a sort of an embarassing social accident.

[tgsovlerkhgsel]

I was thinking more of pumping air across a surface coated with a catalyst. Although a releasable catalyst would also be an interesting option. Not sure if flame farts would be a hindrance or a feature.