As with other high-risk activities, I think gambling on climate change is irresponsible and reckless, even if the people making that bet turn out to be right.
If a person runs across a minefield in order to experience the thrill of danger, few people are likely to congratulate them for their bold choice in the face of uncertainty. Even if you get away with it, it is foolish to run careless risks, especially when the consequences of getting it wrong are severe. This is why Russian Roulette is commonly regarded as an absurdly irresponsible pastime.
Say there is some powerful negative feedback that climate scientists haven’t yet identified. And say it manages to reduce the severity of climate change substantially. Imagine it is 2100 and we are looking back at 2012. I think the people considering the problem from that vantage would be quite willing to recognize how scary climate change looked in 2012. I also think they would be willing to chastise us for our inactivity on the problem, even in a scenario where it worked out that our most extreme fears for what climate change might mean weren’t recognized. Rather than being concerned about climate change ‘alarmists’ who called for action, I suspect impartial citizens in 2100 would be critical of the people who wanted us to plow heedlessly on with fossil fuel development, despite the serious outstanding questions on what effect that would have on the future of human civilization.
From any rational perspective, it makes sense for the world as a whole to take serious action to reduce the seriousness of climate change and the probability of extremely bad outcomes. The problem is that this course of action is not in the short-term interests of many individuals, including powerful people whose wealth and influence is rooted in the status quo.
The real question, when it comes to climate change, is how to make individuals, companies, and countries behave more like they would if they were taking the rights and welfare of everybody seriously. Something like the Categorical Imperative (or even the Harm Principle) provides the moral backing for this view. The question is how to discourage selfish and destructive behaviour while encouraging the cooperation and sacrifice that are required to protect the planet and discharge our duties with respect to future generations.