How long can we sustain the unsustainable?

The rapid increase in the world's population as a whole, the presence of many people that live below the level of any equitable living standards, the emergence of large and rapidly developing economies such as India's and China's, and the profligate model of the American lifestyle (and to a slightly lesser extent, the Western European) have all contributed to concern over the "carrying capacity" of the planet. How many people can obtain adequate amounts of clean water, food, and shelter, let alone automobiles, computers, and a constant supply of consumer goods? The environmental group Bioregional.com calculates that if everyone on earth adopted the British lifestyle, it would require three planets to support. The American lifestyle would require seven planets, but we still only have one. Will wars and catastrophes be the only way to know when those limits have been reached?

The growing awareness of environmental consequence, and the sense that "we can't go on this way" without serious adverse consequences for future generations underlies the development of the term sustainability. The expression was first put into widespread political use by the United Nation's World Commission on the Environment and Development, which issued a report in 1987 known as the Brundtland Report, named after its chairperson, Gro Harlem Brundtand, the former prime minister of Norway.

Although it draws on scientific study and environmental forecasts, the concept of sustainability is a political and moral term, like justice or freedom, and the history of sustainability as as much social, political, and economic as it is environmental.