Factsheets

Biodiversity, or biological diversity, describes the variability among living organisms across terrestrial and aquatic ecosystems, and the ecological complexes of which they are part.¹ Biodiversity shapes the ecosystem services that contribute to human well-being — material welfare, security, resilience, social relations, and health.² Biodiversity is considered on three levels: species diversity, genetic diversity, and ecosystem diversity.³

Species Diversity

• Species diversity can be measured in several ways, including diversity indices (species richness and evenness), rank abundance diagrams, and similarity indices.⁴
• Of the estimated 8.7M eukaryotic (complex celled) species on Earth, 86% of land species and 91% of ocean species have not yet been described.⁵ Over the course of 250 years humans have taxonomically classified over 1.2M species.⁵ As of 2024, 57,033 plant and animal species are listed in the U.S.⁶
• Freshwater habitats account for only 0.01% of the world’s water and make up less than 1% of the planet’s surface, but they support one-third of all described vertebrates and nearly 10% of all known animal species.⁷
• One study suggests that while tropical reefs have more diverse fish communities, it is polar waters that are hotspots of fish speciation (formation of new species) — contrary to much of the previous thinking about evolution.⁸
• Over half of the world’s species are estimated to reside in tropical forests, with the Amazon rainforest alone containing more than 10% of global terrestrial biodiversity.^9,10 Nearly 25% of all marine fish (over 1M species) rely on coral reef ecosystems to survive.¹¹

Genetic Diversity

• Genetic diversity refers to the variation within species (for both the same population and populations living in different geographical areas). Individuals within a species have slightly different forms of genes through mutations, where each form (an allele) can affect species physiology. These variations lead to differences, which are necessary for species to maintain reproductive vitality, resistance to disease, and the ability to adapt to changing conditions.³
• More than 10% of genetic diversity in threatened and endangered species may already have been lost.¹²

Community/Ecosystem Diversity

• Ecosystem diversity describes the variety of biological communities and their associations with the ecosystem of which they are part.³
• Within ecosystems, species play different roles and have different requirements for survival (i.e., food, temperature, water, etc.). If any of these requirements become a limiting resource for a species, its population size becomes restricted.³

Goods and Services

• Ecosystem services are the conditions and processes that enable natural ecosystems to sustain human life. Ecosystem services include: air and water purification; mitigation of floods and droughts; detoxification and decomposition of wastes; generation and renewal of soil and soil fertility; pollination of crops and natural vegetation; dispersal of seeds and translocation of nutrients; protection from the sun’s ultraviolet rays; stabilization of climate; and moderation of temperature extremes and the force of winds and waves.¹³
• Biodiversity improves several ecosystem services, including crop and fishery yields, wood production, fodder yield, resistance to plant invasion, carbon sequestration, soil nutrient mineralization, and soil organic matter.¹⁴
• Global ecosystem services provided by wetlands are valued at over $47T annually, almost half of that being provided by coastal wetlands.¹⁵

Biodiversity, Ecosystem Services, and Human Well-Being²

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Loss of Biodiversity

• Since 1955, biodiversity loss due to human activities was greater than at any time in human history, driven by habitat loss from land-use change, agriculture, over-exploitation, pollution, invasive species, and climate change.^2,16
• Climate change is likely to become the largest threat to biodiversity, in part because it affects areas uninhabited by humans. Impacts on some ecosystems are approaching irreversibility; heat extremes and mass mortality events have resulted in the local loss of hundreds of species.^16,17
• Higher temperatures could increase drying and fire risk, resulting in dieback in the Amazon, which has the highest biodiversity of all forests and stores an amount of carbon equivalent to 15-20 yrs of global CO₂ emissions. Deforestation rates in the Amazon in 2016-2020 increased 92% compared to 2005-2010.^{10,18, 19}
• Habitat loss increases GHG emissions; 11% of global emissions result from deforestation and forest degradation. Over-fishing and -harvesting also contribute to a loss of genetic diversity and species abundance.^20,21
• During Canada’s 2023 record-breaking fire season over 18M ha burned, an area roughly half the size of California.^22,23

Major Risks to Threatened Species²⁴

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Biodiversity Loss due to Agriculture (See U.S. Food System Factsheet)

• Seven agricultural commodities (cattle, oil palm, soy, cocoa, rubber, coffee, wood fiber) accounted for 26% of global tree cover lost from 2001-2015, replacing 71.9M ha of forest.²⁵
• Of the 30 mammalian and bird species used extensively for agriculture, half account for over 90% of global livestock production.²⁶ Genetic diversity within breeds is declining, and 24% of 8,803 livestock breeds identified are classified as at risk of disappearing.²⁷
• Of 30,000 wild and 7,000 cultivated edible plants, 30 provide 95% of dietary energy. Wheat, rice, and maize provide >50% of plant-derived calories, globally.^28,29 Between 1900 and 2000, around 75% of the genetic diversity from crops was lost.²⁹

Extinction

• In Earth’s history, there have been five mass extinctions, time periods where over 75% of species disappear over an interval of 2 million years or less.³⁰
• Globally, the relative abundance of monitored wildlife populations has declined an average of 69% since 1970.³¹ Freshwater species have declined the most globally (83%).³¹ As of 2022, 211 plant and animal species have gone extinct in the U.S. and 2,288 are threatened or endangered.^6,32,33
• The current rate of extinction is 100 to 1,000 times higher than pre-human rates.³⁴ Up to 1M species may be threatened with extinction in coming decades.³⁵

Federally Listed Endangered Species by Taxa³⁶

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Sustainable Actions

Policy

• The Endangered Species Act (ESA) (1973), administered by the Fish and Wildlife Service and the National Marine Fisheries Service, aims to protect and recover imperiled species and the ecosystems they depend on.³⁷
• As of 2024, 194 countries have National Biodiversity Strategic Action Plans for the conservation and sustainable use of biological diversity.³⁸ Globally, over 238,000 protected areas (such as national parks and reserves) have been established, covering nearly 15% of the land and 7.3% of the sea.³⁹ The size of protected areas is now 19 times larger than in 1962.³⁹
• In 2021, President Biden signed an executive order with the goal of conserving 30% of U.S. lands and oceans by 2030.⁴⁰ 

Global Initiatives

• The UN developed a list of Sustainable Development Goals (SDGs) that commit to preserving biodiversity, among other things. Fulfilling the SDGs has the potential to greatly increase biodiversity and its associated benefits.⁴¹
• In 2022, the Kunming-Montreal Global Biodiversity Framework was adapted by the Convention on Biological Diversity. It includes 23 targets for reversing habitat and species loss, including protecting 30% of the world’s terrestrial and marine areas by 2030 (“30x30”).⁴²