Our fossil fuels are being consumed. Our air is filling with carcinogens. We are rapidly approaching the limit beyond which Earth can no longer sustain us as a population. The development of new, more energy-efficient technologies can help to slow the pace at which we consume Earth's dwindling resources. But it cannot slow it enough to overcome the effects of rampant population growth and unchecked consumption of soil, energy and water.
Most people find the thought of taking measures to slow population growth repugnant.
Many consider China's regulation of children per family a violation of human rights. I feel that very few things should supercede individual will, but ensuring the continued survival of our species is definitely one of them. Suppose we only cut down on the consumption of energy per individual but leave population alone. We could simply reduce the human standard of living in order to stop using most resources. I say the former.