this is exactly the ecological mindset I was talking about. To use the example he uses: Boulder, Colorado, if it grows at 5% per year, will start running out o

this is exactly the ecological mindset I was talking about. To use the example he uses: Boulder, Colorado, if it grows at 5% per year, will start running out of livable space near the town centre. As it expands, property prices will increase and adapt to the rising demand, and growth will slow as the once-attractive city becomes less affordable and less attractive. The councillor who wants 5% growth now (because at this point in time, 5% is fine) might be perfectly aware that 5% growth can't be continued for 70 years. That wasn't the question he was asked - having a single idealised growth rate for all time is ridiculous. The growth rate will need to adapt to circumstances. The part about coal consumption is also simplistic and naive, because it doesn't take price into account. If coal becomes scarce, the price rises, and demand drops. You can cheerfully say "coal will last 1000 years" (if you wanted to, but why you'd want to is another question), because coal consumption is not going to continue at a steady pace until suddenly there's no more coal. As the coal stocks dwindle, the price will go up and less critical uses of coal will stop, and demand will decrease, until eventually 1000 years from now, the last piece of coal is in a museum and way too expensive to burn. The "peak oil" thing that he talks about is the perfect example. Everyone (for good reasons) thought we'd hit peak oil in 2008. Then the oil price rose enough to make fracking viable, so natural gas took over providing energy for a bunch of things that we'd been using oil for (and they also found more oil fields), and suddenly there's enough oil and western civilisation continues as normal. The whole thing was a huge false alarm and the Hibbert curve is expanded yet again. anyway, interesting talk, thanks for sharing :)