Scientific agreement on the need for drastic action to combat climate change has prompted the search for ways to ease humanity's increasing burden on the planet, including consideration of population growth and consumption habits.
The human population has greatly increased over the last 200 years, from 1 billion at the beginning of the 19th century to almost 6.8 billion today. Given that massive environmental damage has increased in the same period, it's easy to see how the population "explosion" could be blamed.
In this context, some environmentalists say population control is the answer to our woes. Their "solutions" range from benign to inhumane, from encouraging the use of contraceptives and family planning, to forced sterilisation and hailing AIDS as a beneficent mechanism for population control.
These often racist "solutions" are inevitably aimed at the peoples of Third World, where famine, and land and water degradation, are rife. However, China's one-child policy did not prevent massive environmental degradation in that country, and the current declining global birth rate has not reduced the rate of damage to the planet.
Birth rates fall as general living standards and women's economic independence and control over their reproduction rise. To further reduce the global birth rate, the cancellation of all Third World debt and a massive injection of resources into Third World countries to enable the development of sustainable agriculture and industry, and women's emancipation, is necessary.
Overconsumption is another popular theory. It asserts that the West must decrease its consumption, although how this can be squared with the functioning of the capitalist market is questionable.
The world needs direct and immediate climate action. Relying on market forces to decide whether companies produce Holden Commodores or Toyota Prius won't solve the crisis any time soon.
In any case, consumption is not a matter of "free" choice, but of choices between goods that capitalist industry presents to us. What is needed is a fundamental change on the production side, whereby the commodities and services available to the consumer are sustainable.
Further, many people in the world suffer from under-consumption: they don't have enough for a decent standard of living. The answer is not further impoverishment for more people, but democratically planned production to meet human needs in a sustainable and humane manner, not to make more profits.
It is less a question of how many people are living than how we are living that is leading to our doom. If 7 billion humans were to live in a society founded on sustainable practices, we would have much less deleterious impact on the environment.