Next week, representatives from 190 countries will meet to discuss how we build a green economy that reduces poverty without destroying the environment. These issues have been close to my heart since I wrote a postgraduate thesis on the “Deep Green” movement and humans’ effect on the environment over twenty years ago. But their importance for future generations has been brought home tenfold to me since becoming a father, and I am proud that I will be leading the UK delegation at the Rio Summit.

At the original Earth Summit in 1992, against the backdrop of Brazil’s disappearing Amazon rainforests, world leaders reached a landmark agreement – that development must not come at any cost. While economic growth is important, if we wreck our environment and leave poverty and conflict unchecked, we’ll all eventually pay the price. And so ‘sustainable development’ was born.

So what about Rio twenty years on? While it is unlikely to be as groundbreaking, it will be just as important as the original gathering. Because the legacy of the 1992 Earth Summit is now under threat. The global banking crisis and continuing troubles in the Eurozone have forced every other agenda to take a back seat. Economic recovery and growth are the priority for states around the world – including the UK. And, according to conventional wisdom, that means putting environmentalism and international development on the backburner.

In my view, that is totally wrong. It isn’t a binary choice between sustainability and growth – these agendas go hand in hand, and it’s for us as Liberal Democrats to make that case loud and clear. Greed and recklessness got us into this mess and more balanced, sustainable economies are the only way out. If we want prosperity to last, we need to protect the resources we have and live within our means. And, if we want stable societies that harness all their potential, we need to tackle hardship and poverty too. For this reason, Brazil is an incredibly apt place to host this summit. Not only because it was where the original summit was held. But because Brazil is one of the fastest-growing economies in the world, overtaking the UK as the sixth largest economy early this year and faces the challenge of balancing environmental and economic priorities.

So it seems right that the summit is in Brazil, where Rio must – once again – deliver a show of solidarity from the international community, and a commitment to deliver a better tomorrow. That means three things need to happen next week:

• National governments need to give their full backing to sustainable, green growth. So the UK will be pushing for more of our partners to adopt something called GDP+. GDP can only ever give a narrow snapshot of a country’s welfare. It says nothing about the state of its natural assets, for example its forests or rivers. It may look as though that country is growing richer, when really it’s destroying the natural capital on which its future prosperity depends. We’re leading the charge on this by setting up a Natural Capital Committee to ensure that the Government’s decision making takes full account of the environment and by producing accounts for UK Plc that include the value of the country’s natural capital. I’ll be pressing others to do the same.
• Rio absolutely must set out a plan for the future. I’m determined we agree the need for a package of Sustainable Development Goals on the big, fundamental issues that resonate with every country around the world: feeding growing populations; ensuring everyone has clean water; and providing access to green energy. That will be no mean feat. Hammering out binding agreements and deadlines will take a great deal of work and an enormous diplomatic effort over the next couple of years. But Rio is the moment to get everyone signed up to the blueprint – giving SDGs real momentum and making it as difficult as possible for states to back out.
• We need to get business on board: the people who will really bring about the shift to sustainability in the global economy. Most firms still have no idea of the impact of their actions on our environment. That needs to change – and their customers and investors have a right to that information too. So the UK will be championing a new, push on ‘sustainability reporting’, getting more publicly listed and large companies across the globe to green their books.

The 1992 summit was a triumph and I hope we can revive the spirit and ambition of our predecessors. But this is a week for looking forward, not back. It’s time to set the agenda for the next twenty years and agree the shared principles and goals that will lead to real sustainable development.

* Nick Clegg is the MP for Sheffield Hallam