Very interesting read, thanks for sharing. I particularly liked the part about the origin of the energy we use and wheter that energy would have heated the planet anyway. Carbon trapped in fossil fuel comes from the sun and would have heated the planet during the Carboniferous. By burning it, we "import" heat from this era. Nuclear fission is "importing" heat from the supernovae that seeded the solar system. However, is geothermal "importing" remnant heat of the solar system's creation, as material collapsed in the Earth's gravity well? The heat from the center of the planet would have traveled to the surface eventually, but it would have taken much longer. Maybe we are "importing" heat from the future instead of the past in this case.

There are two things he didn't mention that seem relevant to me. Firstly, that entropy can go down locally. Of course it always rises in a closed system, but the Earth surface is not a closed system. Life, an incredibly organized machine risen from just photosynthesis or chemosynthesis, is an exceptional example of entropy locally decreasing because of external influx of energy from the Sun and the center of the Earth.

Secondly, he justly warned about gathering energy from outer space and importing in on Earth, something that I had never considered. But what if we used this energy in outer space as well? This seems like a good motivation for space colonization. That's a (probably foolish) dream that could be compatible with exponential growth beyond what is available on Earth.