All species have a deep survival instinct. They do everything they can to secure their own survival chances. And that's as true of humans as it is of the Siberian tiger or the lowliest of bacteria. We humans even have a name for our survival instinct: it's called 'sustainable development'. Which means, quite simply, living on this planet as if we intended to go on living here forever.
It was only about thirty years ago that it started to dawn on people that our survival instinct had somehow got buried in the pursuit of ever-greater material prosperity. To generate that prosperity we were literally laying waste to the planet, tearing down forests, damming rivers, polluting the air, eroding top soil, warming the atmosphere, depleting fish stocks, and covering everything with concrete and tarmac.
Even then, experts like Thomas Lovejoy (Lecture 2) were warning of the impact of all this on other creatures - or biological diversity, as the jargon now has it. The United Nations Environment Programme has calculated that today's rate of extinction is running at more than 10,000 times what it would naturally be without the impact of the human species. And as our numbers grow, by an additional 85 million or so a year, the pressures on the planet and its life support systems (on which all species depend, including ourselves) continue to mount year by year.
To start with, most politicians and business people dismissed these warnings as the overheated scaremongering of 'weird and wacky' environmentalists. But the scientific evidence kept on getting stronger, and in 1987 a group of leading experts under the chairmanship of Gro Harlem Brundtland (Lecture 4) produced a report (Our Common Future) which said quite simply that we had no option but to change our ways or ultimately risk our own extinction.
And the only alternative to the prevailing model of economic growth that takes no account of either poorer people or the planet was sustainable development: "development that meets the needs of the present without compromising the ability of future generations to meet their own needs."
This was the first time the social aspect of sustainable development was given such prominence. Poverty is one of the greatest drivers of environmental destruction, and for development to be truly sustainable we have to address ourselves as much to poverty alleviation, education and better healthcare for all as we do to climate change and toxic pollution. This message was powerfully reinforced by the 1992 Earth Summit, the greatest ever gathering of world leaders, which unambiguously re-asserted both the unsustainability of our current model of progress and the pressing need for a sustainable alternative.
Nearly 10 years on, it has to be said that progress has been pretty slow. True enough, sustainable development is hardly the sexiest of concepts to drive the required transformation in our societies and economies.
And there are so still many misunderstandings about what it really means.
It doesn't require, for instance, an end to economic growth as some have argued, but rather the kind of economic growth that is environmentally sustainable (ie. it doesn't go on eroding those critical life support systems) and socially equitable. As John Browne (the Chief Executive of BP Amoco) points out (Lecture 3) this represents a huge challenge to all industries but it also offers huge opportunities. Only recently has it become clear to the business community that looking after the environment is completely compatible with looking after shareholders. The notion of eco-efficiency (reducing costs by eliminating waste and pollution and maximising resource efficiency) underpins this business case for sustainable development.
However, far too few big companies have really seized hold of this challenge. What's more, as critics like Vandana Shiva cogently argue (Lecture 5), the same companies are the principal drivers of a process of economic globalisation that may be accelerating environmental destruction and further widening the gap between rich and poor.
For governments around the world, sustainable development is proving a tough nut to crack. After 250 years or so promising people more and more through permanent economic expansion, it requires real political leadership to start shifting the emphasis onto quality of life and a more balanced and sustainable pattern of economic development. Such changes can only be brought about by consent, not by political diktat. Chris Patten (Lecture 1) was one of the first politicians in the UK to address this democratic challenge as the Secretary of State for the Environment responsible for the UK's first White Paper on Sustainable Development, Our Common Inheritance, in 1990.
The scale of the challenge is daunting. But as all this year's Reith Lecturers will point out, things are now moving in the right direction, albeit too slowly and too patchily.
But sustainable development is not a single issue, like 'the environment' or 'world trade'. It is essentially a different model of progress, balancing the social and economic needs of the human species with the non-negotiable imperative of living within Planet Earth's natural limits. His Royal Highness, The Prince of Wales (Programme 6) has been at the forefront of the debate on Sustainable Development for many years. For him, and for others, it is as much a challenge to our philosophy and personal values as to our political and economic systems, requiring as it does a dramatic shift from an ethos of exploitation and domination to one of stewardship and global responsibility.
*Jonathon Porritt has been one of the most influential advocates on behalf of the environment over the past 25 years. He is Programme Director of the Forum for the Future. He has been closely involved with The Prince of Wales' Business and Environment Programme.