A peek behind the figures

30 September 2010 | News story

The ‘global extinction crisis’ has been in the news for a while now and conservationists are constantly throwing figures at us to illustrate the overwhelming scale of biodiversity loss. “Twenty-one percent of all known mammals, 29 percent of all known amphibians, 12 percent of all known birds, 35 percent of conifers and cycads, 17 percent of sharks and 27 percent of reef-building corals are threatened with extinction” - many of us could lose sleep over this alarming data. But what exactly does it mean? Who calculates these figures and how? How do we know that a particular species is Vulnerable, Endangered, or Extinct?

This data comes from the latest assessment of The IUCN Red List of Threatened Species™, the world's most comprehensive inventory of the global conservation status of plants, animals and fungi and the most authoritative guide to the status of biological diversity. Although overwhelming, this information is extremely important to anyone who isn’t indifferent to the ongoing decline in biodiversity. It serves as the principal source of information on biodiversity for governments, the private sector and multilateral agencies, responsible for natural resource use, and environmental treaties.

Compiling this information involves the combined efforts of some of the best scientists in the world: the IUCN Species Survival Commission and Red List partner organizations. This is a network of some 7,000 species experts working in almost every country in the world. Altogether, this network holds what is probably the most complete scientific knowledge base on the biology and current conservation status of species.
But how exactly does it work?

“To evaluate the extinction risk of thousands of species and subspecies, the IUCN Red List uses a set of quantitative criteria,” says Craig Hilton Taylor, IUCN Red List Unit Manager. “These criteria are relevant to all species and all regions of the world.”

There are nine categories in the IUCN Red List system: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient, and Not Evaluated. Species threatened with extinction – those that are Vulnerable, Endangered, and Critically Endangered – are classified into the categories through a set of criteria that form the heart of the system. These criteria are based on biological factors related to extinction risk, and include the rate of decline of the species, the size of its population, the area of its geographic distribution, and the degree to which the species’ population and distribution are fragmented and declining.

“Species assessments on The IUCN Red List are generated through a combination of on the ground data and the knowledge of thousands of the world’s leading species scientists,” says Caroline Pollock, IUCN Red List Programme Officer. “Contributions are made by members of IUCN’s Species Survival Commission, the IUCN Red List Partnership and other experts. We use statistical analyses to calculate the decline rate and population size of the assessed species."

Based on this information, the Red List identifies and documents species that are most in need of conservation action. It also provides a global index of the decline of biodiversity and a baseline from which to monitor the future status of species. The information it contains is crucial when setting local conservation priorities and when guiding conservation action. It also helps influence national and international policy, and provides a scientific basis to international agreements such as the Convention on Biological Diversity (CBD) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

While the Red List contains assessments of all known species of mammals, birds, amphibians, reef-building corals, freshwater crabs, cycads and conifers, the vast majority of the world’s species are still poorly represented, including many plants, invertebrates, reptiles, fishes and fungi. And there is still a lot to be discovered: globally, only 1.9 million species have been described, though the estimated number of species is thought to be somewhere between 10 and 20 million.

“Currently there are over 52,000 species on the IUCN Red List”, says Simon Stuart, Chair of IUCN Species Survival Commission. "The objective is to expand the Red List to include 160,000 species, making it more representative of the diversity of life, thus providing a solid base for conservation planning decisions. However, this will require a significant increase in funding as over USD 60 million would be needed to complete the assessments.”

For more information, please contact:
Craig Hilton Taylor, IUCN Red List Unit Manager,
Craig.hilton-taylor@iucn.org