I agree there is a moral hazard / perverse incentive when it comes to alarmism, especially in politics (eg, specious references to "mushroom clouds" in the run-up to the Iraq invasion).
But as good Bayesians, we also have to consider the opposite case: crises and "black swan" events do happen. How do we filter signal from noise? We probably could have benefitted from more "enlightened alarmism" re: COVID in Jan/Feb 2020, when billions in preventative measures could have saved trillions to world GDP (and millions of lives).
It's a double-bind politically: given a non-trivial long-term risk, how does one frame its urgency? A calm and measured tone spurs little action (the unsqueaky wheel doesn't get the grease); a tone of urgency and panic bypasses badly-needed rational faculties, and/or flips the "bullshit detectors" based on the history of proverbial boys crying wolf.
While I'm not opposed to FDR-ish green infrastructure plans, the answer from economists is undramatic and uncontroversial [0]: tax the externality to establish a price signal, and return the dividend back to citizens, whose consumption behaviors then change in response to those signals [1].
Of course, we've had to contend with decades of FUD from vested O&G interests, no different than the tobacco cancer debacle [2], despite having had credible evidence for AGW since the late 70's. I'm happy to concede the potential for scientific groupthink and perverse Big Government incentives on the green side, so long as we're also acknowledging the enormous financial incentives for muddying the waters (uncertainty = inaction = status quo = profit).
[0] https://www.wsj.com/articles/economists-statement-on-carbon-...
[1] https://en.wikipedia.org/wiki/Pigovian_tax
[2] https://www.barbarafreese.com/industrialstrength-denial