Putting myself in a position of someone who really cared if we could reverse global warming as soon as possible(2), I would note that because there are a lot of positive feedbacks in the system, and that the momentum is what is important for positive feedbacks (3), actions that have good short term results are more urgent than those with long term results. Residence times for CH4 are approximated to 10 years, while those for CO2 are 100 years. CO2 captured or gathered from the atmosphere is valueless, is complicated to sequester and per volume has much less carbon credit. CH4 is a useful and valuable fuel, is easy to dispose of and is much more potent warmer per volume. Branson's prize might be very easily won by capturing ambient CH4 equivalent to the required CO2 capture.
The conclusion is obvious - It would be very effective if CH4 was treated like CFC's. ie completely separate target than CO2. Tight emmission standards and it being treated like a serious pollutant could dramatically reduce it, in a relatively short timeframe. Targets, as well as reflecting what kind of world we want in the future, should reflect what is reasonably possible. Our addiction to CO2 emmissions will take excruciatingly high Carbon taxes to reduce substantially (even though the net cost to society will be negligible - see Tobacco taxes). Even though best estimates by the latest climate models show that anthropogenic CH4 has only contributed a fraction to the net warming power, it is conceivable that we could reduce emmissions form both anthropogenic and natural sources, so the cooling power of capture may be much greater than the warming fraction these climate scientists are promoting.
(1) It would pay to reiterate that I believe that if the consequences of global warming are very severe, this is a fair punishment for our collective sins and we should take it on the chin.
(2) An alternative theory is that climatologists would prefer a "perfect storm" of warming first - to prove their point and to convert the masses from the fear factor.
(3) One point that climatologists fail to make is that a same positive feedback causing accelerated warming on a warming trend, will actually help cool quicker on a cooling trend.