While I agree with your general assessment of our piggish ways and unsustainable life "style" I don't agree with your assessment of thermodynamics. The problem with fossil burning is it introduces millions of years worth of archived solar energy in months time whereas the Earth has reached homeostasis with the Sun's present load of energy and since we can't create nor destroy energy, no amount of usage of that same load of solar (or a tiny fraction of it) would cause any more heat than the original Sun does unless we start collecting from space which is possible.

However, unlimited Fusion energy COULD bring about the scenario of heat death, not by carbon but by actual heat if we don't become quite frugal and efficient in our use.

The best news is that we can optimize our energy usage using AI that is trained on ecosystems, biology, climate and Earth Sciences. However AI itself is quite energy intensive currently but that will change when quantum computing is used more. AI can optimize personal and cargo transport to be orders of magnitude more efficient as well. There is a reason all of these things come along at the same time. Nature loves efficiency.