CBD Strategic Goal: B. Reduce the direct pressures on biodiversity and promote sustainable use

Main Aichi Biodiversity Target: Target 12: By 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained

Secondary Aichi Biodiversity Targets: Targets 5, 6, 7, 8, 10, 14

CBD AHTEG Headline Indicator: Trends in abundance, distribution and extinction risk of species; Trends in extent, condition and vulnerability of ecosystems, biomes and habitats; Trends in pressures from unsustainable agriculture, forestry, fisheries and aquaculture; Trends in pressure from habitat conversion, pollution, invasive species, climate change, overexploitation and underlying drivers; Trends in distribution, condition and sustainability of ecosystem services for equitable human well-being

CBD Operational Indicator: Extinction risk trends of habitat dependent species in each habitat type

Key Indicator Partners:      

Associate Indicator Partner:

Other conventions or processes using the indicator: RLIs have been widely adopted at the policy level, being used to report against the CBD 2010 Biodiversity target, the UN Millennium Development Goals, by CITES, CMS (and its agreements: AEWA, ACAP Raptor MOU), and for regional policy fora (e.g., SEBI in Europe). It has been well profiled in global assessments such as the Global Biodiversity Outlook-3 and Global Environment Outlook 5.

Development Status: Ready for global use; ready for national use for those countries with sufficient baseline data

Background: Species and the ecosystems of which they are part provide a range of goods and services which support everyday life. This biodiversity is essential for livelihoods and the cultural integrity of people. Yet biodiversity is currently being lost at an alarming rate due to human activities. At present, species extinction rates exceed background rates by two to four orders of magnitude.

Species are the most intuitive unit of biodiversity, and one which resonates with the public and about which we have a relatively good understanding. The IUCN Red List is a well-established and respected system for classifying species by their relative risk of extinction.

The IUCN Red List Index (RLI) shows changes in the overall extinction risk of sets of species over time, with RLI values relating to the proportion of species expected to remain extant in the near future without additional conservation action. The RLI measures the overall rate at which species move through IUCN Red List categories towards or away from extinction. It is calculated from the number of species in each category (Least Concern, Near Threatened, Vulnerable, Endangered, Critically Endangered, Extinct), and the number changing categories between assessments as a result of genuine improvement or deterioration in status (category changes owing to improved knowledge or revised taxonomy are excluded).  Tracking the net movement of species through the Red List categories provides a useful metric of changing biodiversity status.

Policy questions addressed by the indicator: What are the trends in the state of biodiversity, as indicated by trends in the overall extinction risk of sets of species.

Additionally, as supplementary questions, what are the trends in different regions, countries, habitats, ecosystems, biomes, realms, ecosystems, taxonomic or other groups of species (including those providing particular ecosystem services); what are trends in the impacts of different threats/drivers, what are the impacts (on species extinction risk trends) of particular responses (eg protected areas)

Levels at which the indicator is currently used: Global, Regional, Sub-global, National

Red List Index for the world’s mammals, birds, amphibians and corals. 

Source: Hilton-Taylor et al. (2009).

An RLI value of 1.0 equates to all species being categorized as Least Concern, and hence that none are expected to go extinct in the near future. An RLI value of zero indicates that all species have gone Extinct. A downwards trend in the graph line (i.e. decreasing RLI values) means that the expected rate of species extinctions is increasing i.e. that the rate of biodiversity loss is increasing. A horizontal graph line (i.e. unchanging RLI values) means that the expected rate of species extinctions is unchanged. An upward trend in the graph line (i.e. increasing RLI values) means that there is a decrease in expected future rate of species extinctions (i.e. a reduction in the rate of biodiversity loss).

The RLI shows that all species groups with known trends are deteriorating in status, as more species move towards extinction than away from it. Amphibians are more threatened than birds and mammals, but corals are deteriorating in status fastest, owing to increased frequency of ‘bleaching events’ brought about by climate change. South-East Asia is the region in which mammals are most threatened and in which mammals and birds have deteriorated most dramatically. This is a consequence of the rapid rate of deforestation of the region’s Sundaic lowlands combined with unsustainable levels of hunting. Birds are most threatened in Oceania, where island species are often susceptible to invasive species that humans have deliberately or inadvertently introduced. The fungal disease chytridiomycosis is the major driver of declines in amphibians.

National RLIs can be calculated either by disaggregating the global indices, or by repeatedly assessing extinction risk at the national scale. Examples of both approaches are currently being written up for publicationhave been published. Many countries have compiled national red lists which form the basis of the latter approach (see www.nationalredlist.org), but so far few have done this twice or more using consistent methods. As they increasingly do so, however, many more national RLIs will become available.

More information about producing national RLIs can be found in the publication, IUCN Red List Index – Guidance for National and Regional Use, available from the BIP webpage for this indicator.

Interested parties can also visit www.iucnredlist.org or contact redlist@iucn.org.

RLIs for further taxonomic groups are in development.

1st generation RLIs (i.e., an RLI based on two data points, necessitating either complete reassessments or employing a retrospective evaluation for an earlier time point alongside an initial assessment) are being planned for:

• Comprehensively assessed groups: conifers (2013); cartilaginous fishes (2016); freshwater crabs (2016); 

• Selected species used for food and medicine (bushmeat and medicinal plants) (2016); selected crop wild relatives (2016); 

• Sampled groups: reptiles; fishes; butterflies; dragonflies; plants (monocots, legumes, bryophytes and ferns) (2016);

2nd generation RLI’s (i.e., three or more data points), necessitating complete reassessments of all species or employing a retrospective assessment, are planned for: 

• Amphibians (2014, 3rd assessment), mammals (2015, 3rd), reef-building corals (2016, 3rd), cycads (2016 3rd); East African freshwater species (2016, 2nd), birds (2016, 7th)