It's a question many people have probably asked themselves, seeing the ever-increasing environmental degradation around the world: why aren't we doing more to protect our planet? And it's not that easy to answer, as it seems such an obvious course of action, given the parlous state the Earth is in. But Achim Steiner has an answer of sorts. He thinks things are so bad that people can't quite grasp it.
He is worth listening to, because there are not many individuals who could be said to have a truly comprehensive overview of the state of the planet. This 50-year-old Brazilian-German is the executive director of the United Nations Environment Programme (Unep), the part of the UN family that deals with planetary ills, and he has spent a long career trying to help communities across the world to develop, without trashing their surroundings and their natural resources base. In other words, without screwing up their future.
Sustainable development, it is called. For more than 20 years it has been thought of as a great idea whose time has come. So why is so much of what is happening on every continent still clearly so unsustainable? "In a sense ... reality has overtaken our cognitive capacity," Mr Steiner says. "I mean the reality of it has overtaken our capacity to understand it, to understand quite what we are causing and unleashing, almost ... I think we have not even begun to understand how serious are the underlying trends that we have brought to bear on the sustainability of this planet.
"A classic illustration is the ... luxury of this continued debate about scientific uncertainty with climate change. If even 10 per cent of what the IPCC [the UN's Intergovernment Panel on Climate Change] said were to come true, it should actually make us sit up and say immediately, 'change course!'." More