So passionate about this topic, I have a full - length blog post in the publishing pipeline for next Monday, but I could not contain myself from writing a few initial opinions on the matter today.
Indeed in my opinion, backed up by 420,000 years of data, there is an initial 3 ppmv / °C change on short term (one to a few years, over the past 50 years of MLO data), increasing to 8 ppmv / °C for long term changes.