Two out of every five species assessed by scientists are threatened with extinction, according to the 2006 World Conservation Union (IUCN) Red List of Threatened Species.
The list acts as a global wake-up call by focusing attention on the alarming state of the natural environment.
Of the 40,177 species assessed, 16,199 animal and plant species are now listed as threatened with extinction, including one in three amphibians and a quarter of the world's coniferous trees, in addition to the one in eight birds and one in four mammals.
The ranks known to be in jeopardy are joined by familiar species like the polar bear, hippopotamus and desert gazelles, together with ocean sharks, freshwater fish and Mediterranean flowers.
'The 2006 IUCN Red List shows a clear trend: biodiversity loss is increasing, not slowing down,' warned Achim Steiner, director-general of the IUCN.
'The implications of this trend for the productivity and resilience of ecosystems and the livelihoods of billions of people who depend on them are far-reaching ... Biodiversity cannot be saved by environmentalists alone - it must become the responsibility of everyone with the power and resources to act.'