an article in Post Carbon, Richard Heinberg writes:
"The Earth is a bounded sphere, and the human economy is an engine that extracts raw materials and produces waste. If we keep that engine’s operation within the bounds of what our planet can absorb or replenish through its normal ecosystem functions, all is well. But if the economy continues to grow year after year, at some point the planet’s systems will be overwhelmed — even if we’re using renewable energy to extract and transform raw materials. Our uses of energy and materials can be made somewhat more efficient, but only up to a point. If the Earth itself were expanding at an ever-increasing rate, perpetual economic growth would pose no problem. Yet last time I checked, the planet hadn’t gotten any bigger — while our demands upon it continue to increase."