By Richard Black
Environment correspondent, BBC News website
Gorillas, orangutans, and corals are among the plants and animals which are sliding closer to extinction.
The Red List of Threatened Species for 2007 names habitat loss, hunting and climate change among the causes.
The World Conservation Union (IUCN) has identified more than 16,000 species threatened with extinction, while prospects have brightened for only one.
The IUCN says there is a lack of political will to tackle the global erosion of nature.
Governments have pledged to stem the loss of species by 2010; but it does not appear to be happening.
"This year's Red List shows that the invaluable efforts made so far to protect species are not enough," said the organisation's director-general, Julia Marton-Lefevre.
"The rate of biodiversity loss is increasing, and we need to act now to significantly reduce it and stave off this global extinction crisis."
One in three amphibians, one in four mammals, one in eight birds and 70% of plants so far assessed are believed to be at risk of extinction, with human alteration of their habitat the single biggest cause.
The tone of this year's Red List is depressingly familiar. Of 41,415 species assessed, 16,306 are threatened with extinction to a greater or lesser degree.
The main changes from previous assessments include some of the natural world's iconic animals, such as the western lowland gorilla, which moves from the Endangered to the Critically Endangered category.
RED LIST DEFINITIONS
Extinct - Surveys suggest last known individual has died
Critically Endangered - Extreme high risk of extinction - this means some Critically Endangered species are also tagged Possibly Extinct
Endangered - Species at very high risk of extinction
Vulnerable - Species at high risk of extinction
Near Threatened - May soon move into above categories
Least Concern - Species is widespread and abundant
Data Deficient - not enough data to assess
Numbers have declined by more than 60% over the last 20-25 years.
Forest clearance has allowed hunters access to previously inaccessible areas; and the Ebola virus has followed, wiping out one-third of the total gorilla population in protected areas, and up to 95% in some regions.
Ebola has moved through the western lowland gorilla's rangelands in western central Africa from the southwest to the northeast. If it continues its march, it will reach all the remaining populations within a decade.
The Sumatran orangutan was already Critically Endangered before this assessment, with numbers having fallen by 80% in the last 75 years.
But IUCN has identified new threats to the 7,300 individuals that remain. Forests are being cleared for palm oil plantations, and habitat is being split up by the building of new roads.
In Borneo, home to the second orangutan species, palm oil plantations have expanded 10-fold in a decade, and now take up 27,000 sq km of the island. Illegal logging reduces habitat still further, while another threat comes from hunting for food and the illegal international pet trade.
So fragmented have some parts of the Bornean forest become that some isolated orangutan populations now number less than 50 individuals, which IUCN notes are "apparently not viable in the long term".
Straight to zero
The great apes are perhaps the most charismatic creatures on this year's Red List, but the fact they are in trouble has been known for some years. Perhaps more surprising are some of the new additions.
"This is the first time we've assessed corals, and it's a bit worrying because some of them moved straight from being not assessed to being possibly extinct," said Jean-Christophe Vie, deputy head of IUCN's species programme.
"We know that some species were there in years gone by, but now when we do the assessment they are not there. And corals are like the trees in the forest; they build the ecosystem for fish and other animals."
The first formal assessment of corals shows many are at risk
IUCN is now embarking on a complete assessment of coral species, and expects to find that about 30% to 40% are threatened.
The most glaring example of a waterborne creature failed by conservation efforts is probably the baiji, the Yangtze river dolphin, which is categorised as Critically Endangered, Possibly Extinct.
This freshwater species appears to have failed in its bid for survival against the destructive tides of fishing, shipping, pollution, and habitat change in its one native river. Chinese media reported a possible sighting earlier this year, but the IUCN is not convinced; with no confirmed evidence of a living baiji since 2002, they believe its time on Earth may well be over.
If so, it will have become a largely accidental victim of the various forces of human development. Not so the spectacular Banggai cardinalfish; a single decade of hunting for the aquarium trade has brought numbers down by an astonishing 90%.
Many African vultures are new entrants on this year's list. But birds provide the only notable success, with the colourful Mauritius echo parakeet making it back from Critically Endangered to Endangered.
Intensive conservation work has brought numbers up from about 50 to above 300.
But the gharial, a crocodilian found in the major rivers of India and Nepal, provides a cautionary tale of what can happen when conservation money and effort dry up.
A decade ago, a programme of re-introduction to the wild brought the adult population up from about 180 to nearer 430. Deemed a success, the programme was stopped; numbers are again hovering around 180, and the gharial finds itself once more on the Critically Endangered list.
Climate of distraction
IUCN says that it is not too late for many of these species; that they can be brought back from the brink.
It is something that the world's governments have committed to, vowing in the 1992 Convention on Biological Diversity "to achieve by 2010 a significant reduction of the current rate of biodiversity loss at the global, regional and national level".
"Governments know they are going to fail to reach that target," said Jean-Christophe Vie, "and not just in terms of a few species - the failure is really massive.
"We know that it is possible to reverse the trend, but the causes are so huge and massive and global, and there is still a lack of attention to the crisis that biodiversity faces."
Many in the environmental movement argue that too much money and attention has gone on climate change, with other issues such as biodiversity, clean water and desertification ignored at the political level.
IUCN's assessment is that climate change is important for many Red List species; but it is not the only threat, and not the most important threat.
There are conflicts between addressing the various issues, with biofuels perhaps being the obvious example. Useful they may turn out to be in reducing greenhouse gas emissions; but many conservationists are seriously concerned that the vast swathes of monoculture they will bring spell dire consequences for creatures such as the orangutan.