Comment by yodon

If you have a mass extinction event and go more than a generation or two without restarting, all the skills and education will be gone which means you're restarting from zero. We needed readily available high grade energy sources to get to high grade renewables, and those trying to restart civilization will as well, but by the time the get there their forest will be consumed just as ours are, and they won't have oil and coal to discover to get them the bridge to solar or nuclear or high tech wind and tidal power.