Species extinction crisis escalates

Posted: 23 November 2004

Author: Maya Pastakia

A total of 15,589 species of plants and animals are threatened with extinction, warns a leading conservation agency. From the mighty shark to the humble frog, the world's biodiversity is declining at unprecedented rate.

St Helena Redwood (<em>Trochetiopsis erythroxylon</em>) is a tree endemic to St. Helena and is Extinct in the Wild. © Rebecca Cairns-Wicks
St Helena Redwood (Trochetiopsis erythroxylon) is a tree endemic to St. Helena and is Extinct in the Wild. © Rebecca Cairns-Wicks
St Helena Redwood (Trochetiopsis erythroxylon) is a tree endemic to St. Helena and is Extinct in the Wild. After settlers arrived on the island, the species was heavily exploited for its excellent timber and bark which was used for tanning hides. By 1718, the species was already extremely rare. Further losses occurred when flax plantations began in the late 1800s. By the mid 20th century, only one redwood survived and this single tree is the source of all the Redwoods known in cultivation today.© Rebecca Cairns-Wicks
The latest Global Species Assessment (GSA), the most extensive and comprehensive to date, warns that 7,266 animal species and 8,323 plant and lichen species are now threatened with extinction. Global extinctions have increased from 766 in 2000 to 784 documented extinctions today, with a further 60 only known in cultivation or captivity.

The GSA released by the World Conservation Union (IUCN) at its third congress in Bangkok this month (17-25 November), forms the basis of the organisation's authoritative, annual Red List survey on threatened species.

One in eight birds (12 per cent) and nearly a quarter of all mammals (23 per cent) are still under threat since the IUCN published its first Red List of Threatened Species in 1996. In addition, a third of amphibians (32 per cent), almost half (42 per cent) of turtles and tortoises, one in four (25 per cent) of conifers and over half (52 per cent) of cydads, and ancient group of plants, are also in jeopardy.

Largetooth Sawfish (<em>Pristis microdon</em>) is a large, Endangered species of sawfish.  © R. Mitchell
Largetooth Sawfish (Pristis microdon) is a large, Endangered species of sawfish. © R. Mitchell
Largetooth Sawfish (Pristis microdon) is a large, Endangered species of sawfish that is wide-ranging in the Indo-West Pacific, in freshwater or inshore coastal waters. The distinctive rostrum that gives the species its name is highly sought after, but is also often responsible for the species becoming entangled in fishing nets as bycatch. Virtually all known populations have experienced very serious declines. The species is also threatened by habitat loss and degradation over most of its range.© R. Mitchell
"Although 15,589 species are known to be threatened with extinction, this greatly underestimates the true number as only a fraction of known species have been assessed. There is still much to be discovered about key species-rich habitats, such as tropical forests, marine and freshwater systems or particular groups, such as invertebrates, plants and fungi, which make up the majority of biodiversity," says Craig Hilton-Taylor, IUCN's Red List Programme Officer.

Human impact

Human activities underpin the current decline of species, says the report. Habitat destruction is the leading threat, while over-exploitation for food, pets and medicines, introduced (or alien) species, pollution and disease are other pressures facing animals and plants. Human-induced climate change is also becoming an increasingly significant problem.

The 2004 assessment shows that threatened species are often concentrated in densely populated areas, particularly in much of Asia and parts of Africa. A major challenge for conservationists will be to balance the needs of large numbers of people, while protecting the biodiversity on which they depend.

Scimitar-horned Oryx (<em>Oryx dammah</em>) is extinct in the wild. © Antonio di Croce
Scimitar-horned Oryx (Oryx dammah) is extinct in the wild. © Antonio di Croce
Scimitar-horned Oryx (Oryx dammah) was once one of the most common large mammals of northern Africa. Overhunting for the animal's meat, hide and magnificent horns, combined with habitat loss and caused major declines in the species and by the end of the 20th century none were known to remain in the wild. Currently listed as Extinct in the Wild, the species is now part of a major captive breeding and reintroduction programme.© Antonio di Croce
"While most threats to biodiversity are human-driven, human actions alone can prevent many species from becoming extinct. There are many examples of species being brought back from the brink including the southern white rhino and black-footed ferret, and thousands of dedicated people around the world are doing their utmost to reverse the extinction rate," he added. "But this cannot continue to be the task of the environmental community alone. Governments and business must commit to these efforts as well."

'Mass extinction'

The rapid loss of species that we are witnessing today is estimated by some experts to be between 50 to 500 times higher than extinction rates in the fossil record. If 'Possibly Extinct' species are included, the rate is estimated to exceed the natural or 'background' rate by 100 to 1,000 times. This is an extremely conservative estimate, as it does not account for undocumented extinctions.

The Corroboree Frog (<em>Pseudophryne corroboree</em>) is a spectacular but Critically Endangered frog. © Harold Cogger
The Corroboree Frog (Pseudophryne corroboree) is a spectacular but Critically Endangered frog. © Harold Cogger
The Corroboree Frog (Pseudophryne corroboree) is a spectacular but Critically Endangered frog that has declined dramatically in distribution and abundance. It is now restricted to a few fragmented populations in subalpine and montane areas of New South Wales, Australia. Fewer than 250 mature individuals are thought to survive in the wild.© Harold Cogger
Unlike the mass extinction events of geological history, scientists warn that one single species - Homo sapiens - appears to be responsible for the current extinction crisis facing the planet today. This has been dubbed "the sixth extinction crisis", after the five known extinction waves in the Ordovican, Devonian, Permian, Triassic, and Cretaceous periods.

Valuing biodiversity

The monetary value of goods and services provided by natural ecosystems, including gas regulation, waste treatment, and nutrient recycling, is estimated to amount to some 33 trillion dollars per year - nearly twice the global production resulting from human activities.

"Governments are starting to realise the value of biodiversity and the critical role it plays in their peoples' wellbeing. Species provide food, medicine, fuel, and building materials. They help filter water, decompose waste, generate soil and pollinate crops. Recognition of this is growing but governments need to mobilise far more resources. The private sector also needs to play a central role by actively promoting and pursuing the sustainable use of the world's natural resources," said Mr David Brackett, Chair of IUCN's Species Survival Commission.

The GSA shows trends in biodiversity over four years since the last major analysis in 2000. It is based on, and released in conjunction with, the 2004 IUCN Red List of Threatened Species. To date, it is the most comprehensive evaluation ever undertaken of the status of the world's biodiversity. The GSA is produced by the Red List Consortium comprising IUCN and its Species Survival Commission, Conservation International and its Center for Applied Biodiversity Science, BirdLife International and NatureServe.

Related links:

The 2004 Red List of Threatened Species

IUCN

From our website, see also:

News: Consumption running up a huge ecological debt

News: Amphibians in dramatic decline

Factfile: Getting the measure of extinction