Society needs to address the fact that with our present population levels and rates of consumption, using the technologies that we accept, we are using more than the Earth can produce sustainably - about 120% more, by some well-reasoned estimates.

That means that there can be no improvement in the quality of life for the half of our people who live on less than $2 per day. Nor can there be improvement in the quality of life for the one in eight of the world’s population who are literally starving without the invention of new, sustainable technologies, without the rationalizing of consumption levels (instead of simply driving them ever higher) and without the reaching of a level population.

Without social justice, there can be no general stability - our aspirations are primarily based on the myth that we can simply go on growing indefinitely without making any tough choices. Certainly sustainable modes of providing energy, food and water, fighting pollution and the depletion of the oceans, and preserving as much biodiversity as possible are important issues we must address if we wish to maintain the world in a reasonable condition for those who follow us.

Peter Raven is coauthor of Biology of Plants (buy this book from Amazon (UK) or Amazon (USA)), and Environment (buy this book from Amazon (UK) or Amazon (USA)).