Back at the first Rio Earth Summit in 1992, the civil society organisations in attendance counted an unusual group among their number. Amid the assorted staffers and activists from environmental and development NGOs, there was a handful of campaigners who had a very different relationship with the Earth: representatives of an astronauts' organisation. Their reason for being there? Having seen the planet from space, they'd learned to view it from a different angle.
That conference saw 114 heads of state bless the Rio declaration of principles, which, among other achievements, gave birth to the United Nations Framework Convention on Climate Change (UNFCCC) negotiations process. These successes have faded somewhat from memory. Today, international summits are best known for complex wrangling and fragile consensus. And yet the current situation is even more urgent. Greenhouse gas emissions are projected to rise by 50% before the end of the century, resulting in a global average temperature increase of between 3°C and 6°C. This is far in excess of the internationally agreed goal of limiting temperature rises to 2°C. Global biodiversity is expected to decrease by a further 10% on today, primarily due to land-use change; the expansion of commercial forestry; infrastructure development and human encroachment; and pollution and climate change. It's estimated that by 2050 we'll need 40% more food, 30% more water and 50% more energy - at a time when resources are increasingly scarce.
But whether they're from industrialised or developing countries, policy-makers won't be able to confront this challenge unless they get their people onside. With the urgency of the situation therefore comes a pressure to find new ways to communicate. Most importantly, sustainability needs to be situated in the everyday. Talking about an intangible threat to the 'environment' will put citizens off. The major environmental victories since the first Rio summit - on acid rain and ozone depletion - had the advantage of being easy-to-understand, emotive causes, with relatively simple origins. Today's challenges, and their solutions, are far more complex. Politicians and their publics favour quick-wins - short-term policies with big impact. Reversing environmental damage is not such an issue.
Above all, it will be vital to stress how environment and economy are linked. Although the natural environment underpins the basis of all economic value, the protection and enhancement of nature is still not considered a strategic economic priority. Our conventional model of economic growth values short-term returns and wealth creation, rather than long-term productive wealth; it treats resource consumption and the loss of ecosystems as a benefit rather than a cost.
As a result, the natural world is being put under such enormous pressure that it does not have the capacity to provide the resources we need to sustain our existing economy, much less to allow it to continue growing. The global economy is navigating directly into the middle of a 'perfect storm' that will halt what we currently understand as economic growth in its tracks. This month's Rio+20 - the follow-up to the 1992 meeting - is a once-in-a-generation opportunity to confront these challenges and redefine the way we understand growth. But this cannot remain the preoccupation of eco-lobbyists. If economies and businesses cannot develop without the natural world, Rio must be of interest to finance ministers as well as environment departments.
Understanding the link between environmental sustainability and the economy is also crucial if present and future generations are to accrue the benefits of continued growth. The contention both of the current British government and its predecessor is that if 'UK PLC' is to compete in the new green economy, it needs to up its game by improving green research and development. In recognising the possible benefits of the 'sustainability transition', developing economies' policy-makers echo their counterparts in rich countries. Already China is leading the world in wind technology production, and looks set to do the same in other renewable sectors. Middle-income countries such as Brazil and Mexico are taking the lead in promoting 'green growth'; Ethiopia, a Least Developed Country, wants to be the green champion of Africa.
Allied to these commitments are other reasons to be optimistic. There's now a strong international push for improved sustainability outcomes, and a UN sustainable development council, led by the Secretary General, has been mooted. Sustainable Development Goals are planned as a replacement for Millennium Development Goals (MDGs), which come to an end in 2015, and David Cameron has been nominated chair of a UN working group to come up with a post-MDG framework. Moreover, the complexity of the issues at stake isn't necessarily a drawback. The huge variety of people affected by environmental damage means there will again be a strong role for civil society at Rio+20. It should also mean a reduced tendency for decision-makers to retreat into isolated policy 'silos', the last thing that effective action needs.
So there's room for hope - for recognising that the ingenuity of people the world over could bring about a second industrial revolution, enabling economies to grow while confronting the greatest challenge the world has faced. With enough support and finance from government and the private sector, the Rio conference should find new, innovative and successful ways to look both at sustainable development and the way we think about the global economy.