> The lifetime in the air of CO2, the most significant man-made greenhouse gas, is probably the most difficult to determine, because there are several processes that remove carbon dioxide from the atmosphere. Between 65% and 80% of CO2 released into the air dissolves into the ocean over a period of 20–200 years. The rest is removed by slower processes that take up to several hundreds of thousands of years, including chemical weathering and rock formation. This means that once in the atmosphere, carbon dioxide can continue to affect climate for thousands of years.
> Methane, by contrast, is mostly removed from the atmosphere by chemical reaction, persisting for about 12 years. Thus although methane is a potent greenhouse gas, its effect is relatively short-lived.
Even then, it's worse by weight over most timescales.
https://en.wikipedia.org/wiki/Global_warming_potential: "In the Fifth Assessment Report of the Intergovernmental Panel on Climate Change, methane has a lifetime of 12.4 years and with climate-carbon feedbacks a global warming potential of 86 over 20 years and 34 over 100 years in response to emissions."
Yes, if you want to "permanently" (i.e. a thousand years at least) sequester carbon from biomass sources you have to burn them to charcoal and bury that.
You can also pump CO2 into deep coal seams, displacing CH4 which is then burned in a closed capture system. The CO2 released from burning the CH4 is also sequestered resulting in a net gain since CO2 preferentially adsorbs to coal at a roughly 3:1 ratio to CH4. Economically viable coal seams are widespread globally, and exist within 50 km of most coal burning power plants in the United States.
