If we aim for what is no longer possible, we will achieve only delusion and frustration. But if we aim for genuinely worthwhile goals that can be attained, then even if we have less energy at our command and fewer material goods available, we might nevertheless still increase our satisfaction in life.

Surveying the available alternative energy sources for criteria such as energy density, environmental impacts, reliance on depleting raw materials, intermittency versus constancy of supply, and the percentage of energy returned on the energy invested in energy production, none currently appears capable of perpetuating this kind of society.

The idea that we industrialized humans are immune to the natural laws that have restrained growth in other species-and humans in past social regimes-is to me so self-servingly blind as to be morally reprehensible.

Early ecologists soon realised that, since humans are organisms, ecology should include the study of the relationship between humans and the rest of the biosphere. ... We don't often tend to think about the social sciences (history, economics and politics) as subcategories of ecology. But since people are organisms, it is apparent that we must first understand the principles of ecology if we are to make sense of the events in the human world.

All of the easy oil is gone and what's left is requiring more energy and money and this has an effect on everything. Our problem is that we've created an infrastructure that's so dependent on oil. As oil becomes more expensive we're going to be locked into the transportation modes that our economy depends on. So we really need to start building an alternative economy before we get caught in a trap of our own making.

Oil depletion and climate change will create an entirely new context in which political struggles will be played out. Within that context, it is not just freedom, democracy, and equality that are at stake, but the survival of billions of humans and of whole ecosystems.

The industrial civilisation is based on the consumption of energy resources that are inherently limited in quantity and that are about to become scarce. When they do, competition for what remains will trigger dramatic economic and geopolitical events; in the end, it may be impossible for even a single nation to sustain industrialism as we have know it in the twentieth century.