I don't think that is true. As for as I recall, the World3 model includes price feedbacks like this. But even if it didn't, one of the lessons of World3 is tha

I don't think that is true. As for as I recall, the World3 model includes price feedbacks like this. But even if it didn't, one of the lessons of World3 is that it takes time for negative feedbacks like this to achieve equilibrium. If the feedback is slow enough, you get overshoots, and those overshoots either are (by definition) or could trigger (as a side effect) environmentally and socially damaging events. In the case of population, for example, the recovery after a large overshoot could take the form of mass famine or civil war. There is another problem with the argument that many free market optimists make about energy: to actually scale up whatever fancy clean-energy technology happens to become economically viable in the future might require huge swathes of our economies to be reconfigured at an impractical rate. To give an example, there are physical limits to how quickly you can ramp up the volume of solar panels, no matter how cheap the technology is, to do with quickly we can ramp up the production of pure silicon, build plants that make solar panels, and train engineers to oversee those plants and install those panels into the grid. Of course, we can't quantify these limits for some mystery future technology, but we can play the game for known technologies, and it doesn't look good. In particular, it seems that it is only really realistic to be off fossil fuels by 2050 if we start transitioning aggressively now using many different approaches --simultaneously. In other words, we need to place a lot of large bets, not just one large bet or several small ones -- see [1] for example. Given the reluctance of the world's largest producers, consumers, and polluters to even get serious about one of these approaches, it seems pretty hopeless that we have the political will to execute on all of them, simultaneously, at global scale, as we need to. As usual, the poor will suffer disproportionately. [1] http://www.aaas.org/news/press_room/climate_change/mtg_200702/socolow_hotinski.pdf http://www.aaas.org/news/press_room/climate_change/mtg_20070...