[photochemsyn]

This article might benefit from a bit more numerical data:

    CO₂ Radiative Forcing:

        1950: Approximately 0.58 W/m² @ 310 ppm 

        2020: Approximately 2.13 W/m² @ 414 ppm


    CH₄ Radiative Forcing:

        1950: Approximately 0.25 W/m² @ 1.15 ppm

        2020: Approximately 0.59 W/m² @ 1.86 ppm

Methane in the atmosphere is oxidized to CO2 with about a 6-year halflife, so:

20-year timescale: CH₄ is approximately 84-87 times more efficient than CO₂.

100-year timescale: CH₄ is approximately 28-34 times more efficient than CO₂.

The other thing to keep in mind is the removal rate:

> "Roughly 56% of annual fossil CO₂ emissions are absorbed by natural sinks—29% by the biosphere and 23% by the oceans—while 44% remains in the atmosphere, driving global climate change. For CH₄, 90% is removed by atmospheric oxidation within roughly a decade, with a small fraction absorbed by soils."

The bottom line? If human civilization really wants to stabilize the concentration of CO2 and CH4 in the atmosphere - which ideally will lead to a stabilization of global temperature and a new climate normal (certainly warmer and wetter, much like Pliocene conditions of 2-5 mya), then elimination of fossil fuel combustion as an energy source really is the only plausible option.

[dylan604]

> CO₂ Radiative Forcing:

That's an interesting scaling. For a ~30% increase in ppm, it's ~400% in W/m^2

[photochemsyn]

It's because of the high-altitude IR windows in the absorption spectrum as I understand it. If CO2 is added at 1 km it really has no effect there since CO2 absorption in these windows is mostly saturated already, but as you climb to higher altitudes ~12 km the lower pressures mean those windows clear up - but a relatively small increase in CO2 starts filling in these windows. The best source I've found for explaining this at the non-technical level is:

https://history.aip.org/climate/Radmath.htm#L_0165

[ahnick]

Great info. What's the source for this data?

[photochemsyn]

IPCC originally, filtered through ChatGPT-4o. The ChatGPT-o1 model is getting pretty good, I gave it this prompt and I didn't see any glaring errors in the output:

> "We want to calculate the total amount of energy required to extract 90,000 tons of natural gas from a gas field in North Dakota, move that gas by pipeline to a port on the Southeastern United States, liquify that natural gas to the LNG state, then ship that LNG by tanker ship with 90,000 ton capacity to its destination in a Polish port in Europe, then re-gasify that product so its end users can consume it. There are thus five stages in this process."

The estimate is that shipping & processing costs are about 17% of the total energy transported, which still gives LNG quite an advantage over coal in terms of CO2 emitted per kilowatt-hout generated, although wind/solar/storage is obviously much better on that metric, and LNG's upfront infrastructure costs are quite high.

[guerby]

Could you ask it to add latest estimate for leaks in methane infrastructure used along the way?

IIRC these estimates were low in IPCC reports vs where they are now.