Prisoner's dilemma is about situation when optimal outcome requires cooperation from all participants.
In the situation with climate change, personal decisions of 99% of Earth population do not really matter.
Cooperation is not consuming fossil fuels. Defection is consuming fossil fuels.
If you cooperate and other defects you suffer climate impact and expensive energy (expensive everything, worse economic growth than others).
If you defect and other cooperates you suffer climate impact but at least you get cheap energy (cheap everything, more economic growth than others).
People, nations, corporations, etc don’t stop using fossil fuels because they incur a penalty against their competitors if they volunteer to and their competitors don’t.
The fossil fuel industry has to be actively sustained through subsidies and government regulation hostile to alternatives. Maybe that wasn't true 50 years ago before the alternatives got viable and cheap, but if it's not true now then why did we stop subsidizing electric cars while we still subsidize oil companies?
I have dined with them countless times at restaurants where they order vegan and I don't. I have never once been "snapped at" about my dietary decisions. Some of these people have dedicated years of their life to non-human animal rights activism.
So I am very skeptical that this shaming occurs at any appreciable scale. I suspect it is mostly psychological projection: one doubts the morality of one's decisions, judges oneself harshly, but experiences this as the judgement of others.