That's rearranging deck chairs on the titanic. And acting as if that's an important thing to spend political capital on is precisely "posturing and pandering."
What should they spend political capital on? Seems like this section is also going to help develop technological solutions: https://en.wikipedia.org/wiki/Paris_Agreement#Ensuring_finan...
How could we fix the climate more effectively? Elect a world dictator / threaten other countries with nuclear annihilation unless they cut their emmissions.
Would we rather live in that world?
One way to ensure that doesn't happen is to put a tax on carbon emissions. Governments then become dependent on fossil fuel usage for revenue and will enact policies that ensure that revenue stream never gets cut off.
I think change absolutely has to come from governments and thus diplomats. Are corporations going to cooperate at a global scale to fix this with no regard for short term profits? Corporations like Exxon knew about climate change 40 years ago. Personally I think we should be litigating against a corporation that would hide something of global importance like that.
Where is the money to research these technical solutions going to come from? The article you linked showed that there were improvements among the signatories even though without the fall of the USSR it would have been 2.7% vs. 4.7%. Still it was something vs. just saying "this problem is too big to solve, let's hope some smart scientist finds a fix before we all die". Had China and the US been adhering to the Kyoto protocol undoubtedly the impact would have been much greater.