This is the radiative forcing due to various factors. Methane's contribution is about 1/3 of CO2's contribution. Controlling methane would be useful and I believe that Jim Hansen includes it in his "alternative scenario" -- even though I posted a link to it earlier today I haven't read it for a couple of years, so I'm not sure.
http://ess.geology.ufl.edu/ess/Notes/070-Global_Warming/IPCC_G2.gif
Thank you for not stating the source of your graph.
I can't understand true believers like you. How is limiting carbon dioxide going to have any meaningful result when there is so much more methane, which is also increasing, and has an effect that is so much greater? You don't have to answer. Adios