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!'."
But we don't say that, Mr Steiner believes, because "there is an accelerating set of trends, from the atmosphere to the biosphere, to our ability to feed ourselves in a world which will soon have nine billion people, that gives us a sense of what will happen in the next 20, 30, 50 years, that we have simply not yet begun to appreciate".
He can see the trends, quite clearly, because it is his job to, and he talks about them vividly: agriculture which is no longer "a management of that one metre of arable land on which we depend for virtually everything that grows" but a process which "very often has become a mining operation"; oceans which have been overexploited to the point where "two-thirds or more of the fish stocks are either at maximum offtake or actually depleting"; carbon dioxide pumped into the atmosphere "to the point where we are actually fundamentally changing the climate prospects of our planet".
Achim Steiner: 'We haven't even begun to understand the damage we are bringing to bear on the sustainability of our planet'
Since this planet's environment is our life support system... I would think that climate change would be on all our minds all the time.