fishstocks, shrinking supplies of unsullied freshwater, the plundering of virgin tropical forests -- all head a long list of problems that campaigners said should be urgently tackled.
"International efforts to save biodiversity fall woefully short of what is needed," Sebastien Moncorps, director of the French committee of the Geneva-based World Conservation Union (IUCN), told AFP.
In its latest update on species numbers, the IUCN said the world was faced with a "major extinction crisis", mainly due to the disappearance of endangered species' habitat.
One mammal species in four and every reptile and amphibian species in three are threatened with being wiped out. In all, 5,500 animal species and 34,000 species of flora are considered at risk.
As for global warming, environmentalists complained the world was now losing its will to deal with what climate scientists say is the biggest man-made threat to human life.
"There now seems to be a widening gap between political declaration and the work on the ground," commented Kaj Barlund, director of the environment and human settlements division at the UN Economic Commission for Europe (UNECE).
"If this gap cannot be narrowed swiftly, there is little hope of seeing the Kyoto (Protocol) targets met. In that case, climate change will accelerate rather than slow down."
Proof of this, said Greenpeace, was the fact that all controversial environment issues were either absent or diluted to nothingness at the Group of Eight (G8) summit in Evian this week.
Two years ago, the European Union led a drive to save the Kyoto Protocol -- a United Nations pact which commits industrialised signatories to cutting emissions of greenhouse gases, that invisible pollution from burning oil, gas and coal which traps solar energy and has the potential to alter the world's climate system.
The EU's salvage operation was triggered by US President George W. Bush's decision to abandon Kyoto on the grounds that it was too costly for the United States' oil-dependent economy and unfair because it did not require fast-growing emerging nations to make any cuts.
Since then, Kyoto has entered a state of limbo. It still requires ratification by Russia to push it over a threshold so that it becomes an international treaty.
But Russia is dragging its feet over this, apparently upset that the financial windfall that it was expecting under Kyoto's carbon-trading market will be much smaller than expected because of the US pullout.
Worse, according to the UN Framework Convention on Climate Change (UNFCCC), greenhouse gas pollution by developing countries, after stabilising during the 1990s, is likely to grow by 17 percent from 2000 to 2010.
World Environment Day on Thursday changes venue and theme each year.
This year's host city is Beirut and the issue is the looming crisis over freshwater, particularly aquifers -- the underground reservoirs that are fast being run down by over-exploitation.
These vital supplies are under increasing stress and strain, Klaus Toepfer, executive director of the UN Environment Programme (UNEP), warned.
"Some two billion people and as much as 40 percent of agriculture is at least partly reliant on some of these hidden stores," he said, ushering in a UNEP report on the state of the planet's "natural underground reservoirs".