We should work to convert every process that uses energy to green energy. Then the issue becomes moot. Make everything electric, make all electricity production renewable (or nuclear). For things that can't easily run off of batteries like intercontinental flights, use electricity to produce methane or ethanol, and accept that this is a lossy process, price it accordingly.

AFAIK, one of the things that produces the most CO2, and that we're not doing very much about (or even discussing) just yet, is the production of concrete.