This table from CleanTechnica shows the CO2 emissions for the 20 largest emitters. Note that China now emits twice as much as the US and that the top 3 (China, US, India) are 50% of the total. If you add the EU (roughly 10%) and Japan and South Korea, that's approximately 2/3rds of total emissions. This is a relatively small group, and it will be much easier to achieve consensus among themselves than at a global forum where all 140 plus countries have a say And note that all the tiddlers, producing roughly 1% or less, nevertheless make up 1/3rd of total emissions. If the top 6 agree among themselves to slash emissions, and in fact they all have programs in place, the rest, including Australia, will be under intense pressure to follow suit.
Disclaimer. After nearly 40 years managing money for some of the largest life offices and investment managers in the world, I think I have something to offer. These days I'm retired, and I can't by law give you advice. While I do make mistakes, I try hard to do my analysis thoroughly, and to make sure my data are correct (old habits die hard!) Also, don't ask me why I called it "Volewica". It's too late, now.
BTW, clicking on most charts will produce the original-sized, i.e., bigger version.