Poaching, pollution and disappearing forests are putting bears under unrelenting pressure, said the 44-page Bears in the Wild study. It points to increased trade in body-parts such as gall bladders and the demand for bear bile, which is used in traditional Chinese medicine.
Bears, once one of the world's most successful carnivores, are now found in just 62 countries and WWF predicts that the brown bear will be wiped out altogether in its Western European habitat.
Britain's own bear population died out 2,000 years ago. France has the most fragile population, with just eight left in the Pyrenees; a situation not helped when a bear reintroduced into the wild was shot last year by a farmer. Spain's dwindling bear population is also under threat: it has around 80 bears in the Cantabrian mountains with their numbers threatened by the snares set for wild boar and poisoning of wolves. In the Italian Alps there are said to be just four bears left, with no breeding recorded in the past eight years.
Central Europe fares better, with Romania home to more than 6,500 - thanks largely to the love of hunting of the former dictator Nicolae Ceaucescu. He had ordered a strict protection and restocking policy to ensure that his hunting expeditions were fruitful. The Russian bear, the nation's national emblem, also enjoys protection and its numbers are said to be upwards of 36,000. However, there was a dramatic rise in poaching in the early Nineties.
According to the WWF's first global review of the world's bears, habitat loss and hunting are having devastating effects on Asia's sloth, sun (honey) and black bears. It is possible that the sun bear is extinct in India and its presence in Bangladesh is doubtful.
As Asian bears decline, increasing numbers of North and South America bears are being hunted to satisfy world-wide demand for bear parts. Logging, cattle ranching and clearance for poppy and coca fields to feed the lucrative drug trade have also seriously affected South and Central American bears.
The Mexican grizzly is now extinct while the spectacled bear struggles for survival in the remaining forest along the spine of Ecuador, Colombia, Venezuela, Bolivia and Peru.
Callum Rankine, of the WWF-UK Campaign for Europe's Carnivores, said: "Urgent action is vital to save western Europe's last bears. Without prompt intervention these bears will become extinct."
The only bears that still live throughout their original range are polar bears. However, they face new threats in the form of chemicals such as persistent organic pollutants. In 1997, Norwegian scientists found several hermaphrodite polar bear cubs with high levels of PCBs in their systems. Global warming of the Arctic coastal habitat may also have negative impact on polar bears, causing winter maternity dens to collapse and the early thawing of spring ice on which polar bears depend to catch sufficient seals.
"Humans and the impact of their activities, will determine the future of bears. A successful bear conservation effort must balance the needs of bears and the needs of people," said Dr Christopher Servheen, co-chair of the International Conservation Union Bear Specialist Group and co-author of the report.