Sometimes you hear a statistic that at first you find hard to believe.
This week, London Remade produced a report on London's ecological footprint that included the fact that if everybody in the world lived like Londoner's in terms of consumption, then we would need two more planet earths to sustain this lifestyle.
Indeed, an area equivalent to a country twice the size of Great Britain is currently needed to sustain London's way of life.
And that factor is wealth. London is the home of many of the world's biggest companies, it is Europe's premier financial centre and houses the world's busiest airport.
This wealth leads to excessive consumption. You often see Londoners wearing the latest fashionable clothes, adorned in I-Pods that will eventually be replaced by the latest model or driving flash, expensive cars.
But there is also exceptional poverty in London. The gap between the haves and the have-nots is wider here than in any other British city. Yet even among the poor, there are high levels of consumption through food wrapped in lots of packaging, through buying cheap clothing that doesn't last to buying old bangers for transport that are close to the end of their lives.
And this pattern is likely to be repeated by most of the other 50 million or so people who live outside of London, especially in big cities like Liverpool, Manchester, and Birmingham.
The reality is that we live in a way that is no longer sustainable. And this applies to the rest of the western world too. As emerging economies grow, they too will live like us and use resources like us. But with only one planet earth, this won't be possible forever.
While recycling will be necessary to ensure that there are plenty of essential resources to go round, it will also require the world to engage in a debate about the way we use what is available while at least maintaining the lifestyle to which we have become accustomed.
This will mean looking at how we conduct international trade, and areas in which we can make our own local environs more sustainable.
Although the debate has barely got off the ground, the recycling industry is already at the forefront of looking to the future to see how humanity will be ready for dealing with this problem.
But it is essential that while we encourage people to recycle, we should also ask them to think about ways in which they can cut down on the resources they use.