By Richard Black
Environment correspondent, BBC News website
With its Geo-4 report, the United Nations tells us that most aspects of the Earth's natural environment are in decline; and that the decline will affect us, the planet's human inhabitants, in some pretty important ways.
Geo-4 provides a check-up on the health of the planet
Feel like you have heard it before? Of course you have, not least from the UN.
So what, you might ask, is special about this report? Why is it worth any more than a cursory headline glance before returning to the party?
Well, first there is the sheer scale. Hundreds of researchers from a huge variety of disciplines have compiled, written and analysed its 572 pages; thousands more have reviewed the various chapters.
Second, Geo-4 covers the whole range of environmental issues, and the links between them.
In these climate-obsessed times, it is often forgotten that issues like forestry, fresh water supplies, agriculture, biodiversity, and the spread of desert land all connect to each other and to climate change.
In the language of James Lovelock's Gaia theory, the Intergovernmental Panel on Climate Change (IPCC) reports that have punctuated 2007 allowed us to take the planet's temperature; Geo-4 shows us what is going on in the blood supply, the lymph system, the intestines and the immune defences.
Third, it explores the links between social trends and environmental decline in a way that is not often done. Which other body, for example, asks whether the divergence we are seeing in the wealth of the richest and the poorest is good or bad for the environment?
And fourth, it is a staging post on a journey which in principle the international community embarked upon 20 years ago; a chance to see how far society has come, and in which direction.
1987 was perhaps the year when the international community, through the United Nations, began to sound as though it were serious about the environment.
It was the year that the World Commission on Environment and Development, chaired by the then Norwegian prime minister Gro Harlem Brundtland, delivered the gospel of sustainability.
When Mrs Brundtland presented the commission's conclusions to the UN General Assembly, in the form of a report entitled Our Common Future, they were well received.
The assembled governments declared they were "concerned about the accelerating deterioration of the human environment and natural resources and the consequences of that deterioration for economic and social development".
They agreed that sustainable development - by which they meant "meeting the needs of the present without compromising the ability of future generations to meet their own needs" - should become a central guiding principle of the UN itself, as well as its member governments.
They called upon governments - ie themselves - to "ensure that their policies, programmes and budgets encourage sustainable development".
Officially, it was now acknowledged that environmental protection and human development were inextricably linked; there could be no sustainable economic development without environmental protection, and no sustained environmental protection without equitable economic development.
The Brundtland Report set the scene for the Rio de Janeiro Earth Summit five years later, which would deliver more specific global commitments on climate, biodiversity, desertification and forests, turning the commission's broad vision into narrower objectives, more measurable and so - perhaps - more achievable.
Our Common Future contained fine words, and fine sentiments; Geo-4 suggests they have not been acted upon.
Almost everywhere it looks, Geo-4 finds evidence of decline in the years since.
Rivers - the lifeblood for millions - continue to be polluted and exploited
From over-fishing and pollution in the oceans to climate-changing emissions in the atmosphere, it concludes that pretty much everything is going downhill.
More greenhouse gases, more widespread pollution, declining availability of fresh water, deforestation, degradation of farmland, ocean acidification - it is hard to come up with a more comprehensive and, frankly, a more depressing list.
Yet humans are living longer; and in most parts of the world, living standards are higher. Unep calculates that per-capita GDP has gone up from close to $6,000 to just over $8,000 over the last 20 years.
So what, you might ask, is the problem?
Marine fish stocks provide perhaps the clearest example.
Three-quarters of marine fisheries are exploited up to, or beyond, their maximum capacity.
Today's industrial-scale fleets deploy giant nets which could fit a phalanx of jumbo jets through their mouths, they use sonar to find shoals of fish and GPS to locate fertile fishing grounds.
Yet they are finding less and less to catch, because there is less and less there; eventually, there may be nothing at all worth hunting.
Oceans may not be able to meet the needs of future generations
There could be no clearer example of a society engaged in unsustainable development; a society that is "meeting the needs of the present", but in doing so is very definitely "compromising the ability of future generations to meet their own needs".
Humans might be living longer and richer lives now, this implies; but environmental degradation must at some point curb or even reverse the trend.
To use the jargon, the world's store of financial capital is rising at the expense of its natural capital, the bits of nature that humans rely on to provide food and water and to re-process our waste.
It finds that the unsustainable label sticks to everything examined by Mrs Brundtland's team: "There are no major issues raised in Our Common Future for which the foreseeable trends are favourable".
Since Brundtland, the world's human population has increased by 34%; although the rate of growth is slowing, it is a long way from stabilisation.
A larger population needs more land to live on and grow food, hence causing more deforestation and more encroachment into areas previously left for nature. It means extracting more water for drinking, industry and agriculture; more energy use and greenhouse gas emissions.
Brundtland suggested developing policies that simultaneously aimed to restrain population growth while reducing both poverty and environmental destruction.
If that was ever feasible, politicians and their advisors now generally consider population growth such a sensitive issue that it has virtually disappeared off the sustainability radar.
By pointing out that global population growth is a significant environmental issue, Geo-4 might just encourage politicians to bring it back out of the closet, so that it can at least be discussed again.
Sustainable development is not the easiest concept to catch up with; certainly it is much harder for a government to measure whether greenhouse gas emissions are rising, or whether economic growth is accelerating than to evaluate whether its overall policy portfolio is sustainable.
Jonathon Porritt has argued on this website that sustainable development is not just a "boring catch-phrase", but the key to a better future for humankind and the natural world.
As he also argued, there has never been more talk about it; in fact, if a tree were planted every time a modern European politician uttered the SD-phrase, loss of forest would probably be a thing of the past.
Geo-4 shows us that if 20 post-Brundtland years have upped the rhetoric, they have done little to change the reality; despite a plethora of good intentions, global society is less sustainable than ever.
Without major changes in direction, we had better hope that the people who believe that human ingenuity, technology and economic growth will always solve our future problems turn out to be right.