Anyone wanting a vision of how the world might look in 50 years' time can today go and stand on the border between the Dominican Republic and Haiti. On the Dominican side they will see a lush, heavily wooded countryside, the result of careful conservation efforts and some brutal action taken against illegal loggers. On the Haitian side of the border, they will see an ecological disaster, of massive soil erosion and deforestation, the result of extreme poverty, government breakdown and the chaos that comes with protracted civil disturbance. The dichotomic starkness of the landscapes facing the viewer is similar to the choices we now face towards the world's environment, based on scenarios painted by a highly credible report issued yesterday under the auspices of the UN: the Millennium Ecosystems Assessment, the work of 1,300 scientists in 95 countries over the past four years.

To be clear: this assessment does not simply begin and end with the arguable (to some, although not to this newspaper) effects of global warming or climate change. It deals more with the impact of the Earth's one species of mammal that has contributed more poison and done more damage to the planet than any other. In the last 50 years, it reports, the human race has drawn heavily on the Earth's natural resources - so much so that in some areas the planet is in danger of becoming overdrawn, leaving our descendants to pay an environmental debt that will dwarf the pensions crisis, and reverse all of the best efforts to lift the world's poor out of poverty.

The report's details are the stuff of nightmares. The effects are slow and often uncertain in their impact. But, as always, the question remains as to what is to be done. Unhelpfully, the assessment is not clear enough on how to protect the remaining ecosystems. It does have some useful suggestions, such as the need to include environmental indicators in a country's national accounts, treating ecosystems as resources as vital as education or health infrastructure. But more important is the need for action to at least preserve what we have now. None of the major parties in the coming general election is promising the sort of dramatic policies that will be required, such as tough and tougher carbon emission targets, tax incentives for households and businesses to use sustainable energy sources, or to abolish the unnecessary farm subsidies that are the expensive relic of a bygone age. Technology and incremental, voluntary lifestyle change will not be enough, as our grandchildren will surely remind us one day.

© 2005 Guardian Newspapers, Ltd.

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