'Countries join forces to save life on Earth", the front page of the Independent told us. "Historic", "a landmark", a "much-needed morale booster", the other papers chorused. The declaration agreed last week at the summit in Japan to protect the world's wild species and places was proclaimed by almost everyone a great success. There is one problem: none of the journalists who made these claims has seen it.

I checked with as many of them as I could reach by phone: all they had read was a press release which, though three pages long, is almost content-free. The reporters can't be blamed for this – it was approved on Friday but the declaration has still not been published. I've pursued people on three continents to try to obtain it, without success. Having secured the headlines it wanted, the entire senior staff of the convention on biological diversity has gone to ground, and my calls and emails remain unanswered. The British government, which lavishly praised the declaration, tells me it has no printed copies. I've never seen this situation before. Every other international agreement I've followed was published as soon as it was approved.

The evidence suggests that we've been conned. The draft agreement, published a month ago, contained no binding obligations. Nothing I've heard from Japan suggests that this has changed. The draft saw the targets for 2020 that governments were asked to adopt as nothing more than "aspirations for achievement at the global level" and a "flexible framework", within which countries can do as they wish. No government, if the draft has been approved, is obliged to change its policies.

In 2002 the signatories to the convention agreed something similar, a splendid-sounding declaration that imposed no legal commitments. They announced they would "achieve by 2010 a significant reduction of the current rate of biodiversity loss". Mission accomplished, the press proclaimed, and everyone went home to congratulate themselves. Earlier this year the UN admitted the 2002 agreement was fruitless: "The pressures on biodiversity remain constant or increase in intensity."

Even the cheery press release suggests all was not well. The meeting in Japan was supposed to be a summit, bringing together heads of government or state. It mustered five: the release boasts of corralling the president of Gabon, the president of Guinea-Bissau, the prime minister of Yemen and Prince Albert of Monaco. (It fails to identify the fifth country – Liechtenstein? Pimlico?) A third of the countries represented couldn't even be bothered to send a minister. This is how much they value the world's living systems.

It strikes me that governments are determined to protect not the marvels of our world but the world-eating system to which they are being sacrificed; not life, but the ephemeral junk with which it is being replaced. They fight viciously and at the highest level for the right to turn rainforests into pulp, or marine ecosystems into fishmeal. Then they send a middle-ranking civil servant to approve a meaningless and so far unwritten promise to protect the natural world.

Japan was praised for its slick management of the meeting, but still insists on completing its mission to turn the last bluefin tuna into fancy fast food. Russia signed a new agreement in September to protect its tigers (the world's largest remaining population), but an unrepealed law in effect renders poachers immune from prosecution, even when they're caught with a gun and a dead tiger. The US, despite proclaiming a new commitment to multilateralism, refuses to ratify the convention on biological diversity.

It suits governments to let us trash the planet. It's not just that big business gains more than it loses from converting natural wealth into money. A continued expansion into the biosphere permits states to avoid addressing issues of distribution and social justice: the promise of perpetual growth dulls our anger about widening inequality. By trampling over nature we avoid treading on the toes of the powerful.

A massive accounting exercise, whose results were presented at the meeting in Japan, has sought to change this calculation. The Economics of Ecosystems and Biodiversity (TEEB) attempts to price the ecosystems we are destroying. It shows that the economic benefit of protecting habitats and species often greatly outweighs the money to be made by trashing them. A study in Thailand, for instance, suggests that turning a hectare of mangrove forest into shrimp farms makes $1,220 a year but inflicts $12,400 of damage every year on local livelihoods, fisheries and coastal protection. The catchment protected by one nature reserve in New Zealand saves local people NZ$136m a year in water bills. Three quarters of the US haddock catch now comes from within 5km of a marine reserve off the New England coast: by protecting the ecosystem, the reserve has boosted the value of the fishery.

I understand why this approach is felt to be necessary. I understand that if something can't be measured, governments and businesses don't value it. I accept TEEB's reasoning that the rural poor, many of whom survive exclusively on what the ecosystem has to offer, are treated harshly by an economic system which doesn't recognise its value. Even so, this exercise disturbs me.

As soon as something is measurable it becomes negotiable. Subject the natural world to cost-benefit analysis and accountants and statisticians will decide which parts of it we can do without. All that now needs to be done to demonstrate that an ecosystem can be junked is to show that the money to be made from trashing it exceeds the money to be made from preserving it. That, in the weird world of environmental economics, isn't hard: ask the right statistician and he'll give you any number you want.

This approach reduces the biosphere to a subsidiary of the economy. In reality it's the other way round. The economy, like all other human affairs, hangs from the world's living systems. You can see this diminution in the language TEEB reports use: they talk of "natural capital stock", of "underperforming natural assets" and "ecosystem services". Nature is turned into a business plan, and we are reduced to its customers. The market now owns the world.

But I also recognise this: that if governments had met in Japan to try to save the banks, or the airline companies, they would have sent more senior representatives, their task would have seemed more urgent, and every dot and comma of their agreement would have been checked by hungry journalists.

When they meet to consider the gradual collapse of the natural world they send their office cleaners and defer the hard choices for another 10 years, while the media doesn't even notice they have failed to produce a written agreement. So, much as I'm revolted by the way in which nature is being squeezed into a column of figures in an accountant's ledger, I am forced to agree that it may be necessary. What else will induce the blinkered, frightened people who hold power today to take the issue seriously?

• A fully referenced version of this article is available on www.monbiot.com