Putin's Russia, and Xi's China, are extremely skeptical of global warming. Russia outright considers it a fraud and conspiracy, Putin has stated exactly that. Plenty in the developing world are on board with that skepticism.
Which is why China is going to keep their emission levels completely uncapped for the next 15 years at least, allowing for dramatic growth in said emissions. The best they've agreed to, is that maybe emissions will fall after 2030 (emphasis on the fact that it's an entirely empty pledge).
I think the science will take a long time to harden beyond its present state. We can project forward estimates but this will refine over time. It's a long-term project.
I doubt this is true without the caveat: ...so long as the energy industry keeps funding an opposition.