The world is not going to hell in a carbon-lined handcart. Not yet. To read the headlines from the United Nations Environment Programme’s latest comprehensive report on Earth’s health, one might be forgiven for concluding that a global environmental catastrophe is now irreversible: we are in the middle of the first mass extinction brought on entirely by humans; our overuse of farmland, fresh water, fish and fossil fuels is beyond critical; there are no major environmental problems “for which the foreseeable trends are favourable”; and the net effect of these problems will be to “put humanity at risk”.

Yet such headlines do the report itself a disservice. It is a valuable document and a vital point of comparison with the 1987 Brundtland Commission report that serves as its template. It also contains as many reasons for cautious optimism as it does for gloom, with the peculiar result that Friends of the Earth’s assessment of it yesterday was more accurate than the authors’. “The steady degradation of the world’s environment threatens the wellbeing of everybody on the planet,” FoE said. From children suffering asthma attacks because of particulate pollution in London to families forced off fragile farmland in the Sahel because of preventable soil erosion, this is undoubtedly true. But it is not by any means a threat to humanity itself.

The report is rich in detail. It notes that the comb jellyfish, accidentally introduced into the Black Sea by international shipping in 1982, had taken over the entire regional marine ecosystem and destroyed 26 commercial fisheries within a decade – a succinct illustration of the fragility of what sustains us and the interconnectedness of trade and the environment. Yet since the comb jellyfish slipped through the Dardanelles these themes have found their proper place in the political mainstream, as the report acknowledges. At the same time, global wealth has soared.

Twenty years ago the Brundtland report gave warning that if large parts of the “Global South” were to avert economic, social and environmental crisis, “it is essential that global economic growth be revitalised”. It has been. World trade has grown ten times faster than world population with a resulting 40 per cent increase in average incomes. The term “Global South” has faded from use, and the Brundtland report’s pleas for more commitment to the work of development banks have been eclipsed by the success of freer trade in lifting millions out of poverty.

Prosperity carries its own environmental risks, including unsustainable fossil fuel use and the seismic shift under way in India and China towards higher meat consumption, with correspondingly heavier burdens on farmland for livestock feed. The surge in average incomes has also bypassed much of Africa, where per capita food production has, shockingly, fallen by 12 per cent since 1981. Yet experience shows that wealth is a prerequisite for better environmental stewardship. Real efficiencies are usually technology-led and costly, from those already used to shrink the ozone hole and cut acid rain to those urgently needed to combat greenhouse gas emissions.

Environmentalists fear, not without reason, that too much even-handedness will breed complacency. Yet hyperbole is worse, especially in the use of projections that depart from observable trends. It undermines the vital case for sustainability, and overstates science’s ability to forecast accurately. The debate on the planet’s health is too serious to leave to alarmists.