For climate change, there's already a lot of existing models out there calculated by much more rigorous metrics than "the Laplace rule" or just naively adding together averages.
We know that every species consumes all available resources until an external force, whether it's predators or environmental collapse checks its growth. Humans are no different - any time a poor person uses a paper straw, a rich one will fly their private jet. Muh backyard arguments on nuclear means we will continue to burn coal and gas as fast as possible, even while renewables help drive up more demand.
So I think it's safe to assume that emissions will continue growing.
[0]: https://cei.org/blog/wrong-again-50-years-of-failed-eco-poca...
FWIW, I'm very much NOT endorsing cei.org, nor saying climate change is not a big problem. Just saying that the track record of climate scientists is not great. Climate change is important enough to warrant the attention of people who can actually predict things.