Banks can be shut down to prevent bank runs, but only temporarily. You can't just close the bank down or heavily restrict withdrawals forever without significant negative consequences. Fighting climate change is not a short term proposition.
Even if you are totally correct, it's irrelevant unless (A) you can maintain democratic support for such collective actions, or (B) you get rid of democracy.
In the US at least, even the democrats don't propose climate regulation strong enough to have a measurable impact on the climate over ten years. People will absolutely resist the moment energy prices go up notably, which will be necessary to measurably affect climate.
The problem isn't that collective action needs to be taken, it's that sufficient collective action won't sufficiently be supported by voters. That's why Democrats aren't proposing it, and that's the actual hurdle that needs to be overcome.