Quo vadis Homo sapiens? -- running towards the abyss!

Taken from the recent book review of SW Running (Science 15 March 2013: Vol. 339 no. 6125 pp. 1276-1277) 

"Scholars around the world have been asking roughly this same question [about the sustainability of human development] since 1972, when the landmark Limits to Growth book appeared (3). More recent analyses—such as the global human footprint, planetary boundaries, and Gaia—address the question from various angles. Each has indicated that another half-century of the current trajectory of human development, consumption, and economic aspirations does not appear possible (4–7).

Smil's final recommendations [in 'Harvesting the Biosphere'] echo others: global population must be stabilized at or below 9 billion; agriculture has to become sustainable, no longer relying on fossil-fuel–based fertilizers and mining groundwater for irrigation; meat consumption must be moderated; and food storage and processing must be improved and wastage minimized. Crucially, the rich nations have to share global resources more equitably with emerging countries, as simply growing more does not appear possible.

Full of recent references and statistics, Harvesting the Biosphere adds to the growing chorus of warnings about the current trajectory of human activity on a finite planet, of which climate change is only one dimension. One can quibble with some assumptions or tweak Smil's calculations, but the bottom line will not change, only the time it may take humanity to reach a crisis point. Systems ecology teaches that the human population and consumption trajectories need a stronger feedback control than currently exists. Either we are smart enough to craft that feedback mechanism ourselves, or the Earth system will ultimately provide it. Unfortunately, the tragedy of the commons suggests that collective international actions to voluntarily reduce consumption are contrary to human nature."

In other words: we know what we'd need to do to save us, but we won't do it.

Homo sapiens is smart enough to know that he's running towards the abyss, but not smart enough to stop running.