Definition and scope

Biodiversity is the variability among living organisms from all sources, including diversity within species (genetic), between species, and of ecosystems; it encompasses the patterns and processes that sustain life and human societies. According to the Convention on Biological Diversity, this three‑level conception is foundational to conservation, sustainable use, and equitable benefit-sharing. Convention on Biological Diversity; CBD Topics.

The term “biodiversity” entered wide use after the National Forum on BioDiversity (Washington, D.C., 1986) and the publication of the volume Biodiversity (1988), edited by E.O. Wilson, which helped standardize usage across science and policy. National Academies Press; NCBI Bookshelf.

Magnitude of diversity

Estimates of global species richness remain uncertain, but a frequently cited analysis predicts about 8.7 million eukaryotic species (±1.3 million), of which roughly 2.2 million are marine; most remain undescribed. PLoS Biology (Mora et al. 2011).

Dimensions and organization

• –Genetic diversity supports adaptation, disease resistance, and long‑term viability of populations, with loss leading to heightened extinction risk and reduced resilience. Convention on Biological Diversity.
• –Species diversity includes richness, abundance, and turnover among communities; it is measured with indices such as richness, Shannon, and Simpson, and increasingly with phylogenetic and functional diversity. book://Anne E. Magurran|Measuring Biological Diversity|Blackwell|2004.
• –Ecosystem diversity spans biomes and habitat mosaics—from tropical forests and Coral reef systems to Wetland complexes—whose structure and function govern nutrient cycling, productivity, and climate regulation. Millennium Ecosystem Assessment (UNEP).

Monitoring and indicators

Global biodiversity status is tracked with complementary indicators and frameworks:

• –The IUCN Red List categories and criteria (version 3.1) provide standardized extinction risk assessments across taxa, enabling trend metrics like the Red List Index. IUCN.
• –The Living Planet Index aggregates vertebrate population trends; the 2024 update reports an average 73% decline in monitored populations between 1970 and 2020, with particularly steep losses in Latin America, Africa, and freshwater systems. ZSL (Living Planet Index 2024).
• –Essential Biodiversity Variables (EBVs), coordinated by GEO BON, define priority measurements (e.g., species distributions and abundance) to standardize observing systems for policy and management. GEO BON; GEO BON Species Populations EBVs.

Trends and drivers of change

The 2019 IPBES Global Assessment concluded that around one million animal and plant species face extinction risk, identifying five direct drivers: land/sea‑use change, direct exploitation, climate change, pollution, and invasive alien species. IPBES Global Assessment SPM.

Observed biodiversity change includes rapid declines in wildlife populations and deterioration of ecosystem integrity, with freshwater biodiversity showing some of the largest losses. ZSL (Living Planet Index 2024); IPBES Global Assessment SPM.

Climate change intensifies risks through warming, extreme events, biome shifts, and coral bleaching, increasing extinction risk as temperatures rise; IPCC AR6 assesses high to very high risks to terrestrial and freshwater ecosystems under higher warming levels. IPCC AR6 WGII Chapter 2; IPCC AR6 WGII Fig. 2.11; IPCC AR6 Synthesis Fig. 3.2.

Nature’s contributions to people

Ecosystems provide provisioning (food, fiber, water), regulating (climate, flood control, pollination), cultural, and supporting services integral to health and economies. The Millennium Ecosystem Assessment synthesized evidence of widespread ecosystem change and service degradation over the late 20th century. Millennium Ecosystem Assessment (UNEP).

Biodiversity for food and agriculture underpins soils, pest control, and genetic resources; despite thousands of cultivated species, global production is concentrated in a few crops, increasing vulnerability. FAO State of the World’s Biodiversity for Food and Agriculture (2019); UN News (FAO report).

Animal pollination supports more than three‑quarters of food crops and most wild flowering plants, with substantial economic value. IPBES Pollinators Assessment; IPBES Pollinators press release.

Conservation policy and law

• –The Convention on Biological Diversity (CBD, adopted 1992) sets three objectives: conservation of biodiversity, sustainable use of its components, and fair and equitable benefit‑sharing from genetic resources. CBD Topics.
• –In December 2022, Parties adopted the Kunming-Montreal Global Biodiversity Framework (GBF), with four goals and 23 targets through 2030, including “30×30” (protecting and conserving at least 30% of land and ocean). CBD GBF portal; CBD Decision 15/4 overview.
• –Other treaties include CITES (regulating international trade through Appendices I–III), and the Ramsar Convention on wetlands (wise use and Ramsar Sites). CITES: How CITES works; Ramsar Secretariat.

Protected and conserved areas are expanding but remain ecologically under‑representative and unevenly connected; as of recent global reporting, terrestrial coverage surpassed 17% while marine coverage remains well below 30%, requiring accelerated, equitable implementation and recognition of Other Effective area‑based Conservation Measures (OECMs). Protected Planet (coverage and reporting); Protected Planet Report hub.

Approaches and tools

Conservation responses include protected areas and OECMs, ecological restoration, invasive species management, sustainable harvest frameworks, and community‑ and Indigenous‑led stewardship, supported by monitoring (e.g., Red List, Living Planet Index) and EBV-based observing systems. IUCN Red List Categories & Criteria; ZSL LPI 2024; GEO BON.

Companies and financial institutions are increasingly evaluating nature‑related dependencies, impacts, risks, and opportunities using the Taskforce on Nature‑related Financial Disclosures (TNFD) recommendations, aligned with the GBF. TNFD Recommendations; TNFD overview.

Historical development of the concept

“Biological diversity” was used in scientific and conservation literature before 1986, but the contracted form “biodiversity,” credited to W.G. Rosen during preparation of the 1986 Forum and popularized by Wilson’s 1988 volume, catalyzed integration of ecology, genetics, and policy under a common term. National Academies Press; NCBI Bookshelf.