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Biodiversity Loss Overview

There are many definitions for biodiversity (short for biological diversity), and they vary. Based on the 3 definitions below, we propose the following:

Biodiversity encompasses all life on earth including its forms, abundance, distributions, interactions, and variations over time.

 “The sum total of all of the plants, animals, fungi, and microorganisms on Earth; their genetic and phenotypic variation; and the communities and ecosystems of which they are a part.”[1]

 “The variability among living organisms from all sources including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part. This includes variation in genetic, phenotypic, phylogenetic, and functional attributes, as well as changes in abundance and distribution over time and space within and among species, biological communities and ecosystems.”[2]

 “Biodiversity is the variety of life, including variation among genes, species and functional traits. It is often measured as: richness is a measure of the number of unique life forms; evenness is a measure of the equitability among life forms; and heterogeneity is the dissimilarity among life forms.”[3,4]

 

  1. Dirzo, R., & Raven, P. H. (2003). Global State of Biodiversity and Loss. Annual Review of Environment and Resources, 28(1), 137–167, p. 138.
  2. IPBES (2019) Global assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Brondízio, E. S., et al., (eds). IPBES secretariat, Bonn, Germany. ISBN: 978-3-947851-20-1, p. 1033.
  3. Cardinale, B. J. et al., (2012). Biodiversity loss and its impact on humanity. Nature (London), 486(7401), 59–67, p. 60.
  4. Note: the number of dimensions across which biodiversity can be measured are a reflection of the complexity of this topic. See, Naeem, S., et al., (2012). The functions of biological diversity in an age of extinction. science, 336(6087), 1401-1406, p. 1403. [“…one community may be called more diverse than another if it has any combination of more species (taxonomic diversity), greater cumulative phylogenetic distance among its species (phylogenetic diversity), greater genotypic diversity within species (genetic diversity), greater distance among species in multivariate functional trait space (functional diversity), higher species turnover across a unit of space (spatial diversity), greater numbers of links per species in the interaction network (network diversity), and more habitat types within the landscape (landscape diversity).”]

The loss of biodiversity has ramifications that potentially raise the issue above all others. Biodiversity loss is:

 Irreversible.[1]
 Accelerating.[2]
 Among the most dangerous threats to human civilization.[3-5]
 Already well past the safe operating space for humankind.[6]
 A risk to assets of enormous economic value.[7,8]
 Arguably among the most unethical acts of humankind.[9,10]

 

  1. Dirzo, R., & Raven, P. H. (2003). Global State of Biodiversity and Loss. Annual Review of Environment and Resources, 28(1), 137–167, p. 138. [“The loss of biodiversity is the only truly irreversible global environmental change the Earth faces today.”]
  2. IPBES (2019) Global assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Brondízio, E. S., et al., (eds). IPBES secretariat, Bonn, Germany. ISBN: 978-3-947851-20-1, Summary p. 24. [“The global rate of species extinction is already at least tens to hundreds of times higher than the average rate over the past 10 million years and is accelerating…”]
  3. Hooper, D. U., et al., (2012). A global synthesis reveals biodiversity loss as a major driver of ecosystem change. Nature, 486(7401), 105-108. [“…our analyses clearly show that the ecosystem consequences of local species loss are as quantitatively significant as the direct effects of several global change stressors that have mobilized major international concern and remediation efforts.” Abstract]
  4. Tilman, D., et al., (2012). Biodiversity impacts ecosystem productivity as much as resources, disturbance, or herbivory. PNAS, 109(26), 10394-10397. [“…the loss of biodiversity may have at least as great an impact on ecosystem functioning as other anthropogenic drivers of environmental change…” Abstract]
  5. Ceballos, G., et al., (2020). Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction. PNAS, 117(24), 13596-13602, p. 13596. [“The ongoing sixth mass extinction may be the most serious environmental threat to the persistence of civilization, because it is irreversible.”]
  6. Richardson, K., et al., (2023). Earth beyond six of nine planetary boundaries. Science advances, 9(37), eadh2458, Table 1, p. 5. [Extinction rates currently estimated at more than 10 times the safe boundary.]
  7. World Economic Forum (2023) The Global Risks Report 2023, 18th Ed., p. 31. [“Given that over half of the world’s economic output is estimated to be moderately to highly dependent on nature, the collapse of ecosystems will have far-reaching economic and societal consequences.”]
  8. Heal, G. (2020). The economic case for protecting biodiversity. National Bureau of Economic Research, No. w27963, p. 11. [“We have seen that a part of the value of biodiversity is in the tens of trillions of dollars, with the total value probably far higher than the numbers suggested in the cases reviewed above.”]
  9. Weinhues, A., et al., (2023). The ethics of species extinctions. Cambridge Prisms: Extinction, 1, e23.
  10. American Museum of Natural History, What is Biodiversity?, amnh.org. https://www.amnh.org/research/center-for-biodiversity-conservation/what-is-biodiversity [“The intrinsic value of biodiversity refers to its inherent worth, which is independent of its value to anyone or anything else. This is more of a philosophical concept, which can be thought of as the inalienable right to exist.”]

IUCN – The International Union for the Conservation of Nature maintains the IUCN Red List of Threatened Species, widely regarded as the preeminent source for global extinction risk data.[1]

World Wildlife Fund – WWF’s Living Planet Report, published every 2 years, analyzes the changes in global biodiversity, particularly the declines in the average size of monitored wildlife populations.[2]

IPBES – The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services is an inter-governmental body supported by 150 states and the U.N. They generate many research reports on biodiversity, including the 2019 Global Assessment which is regularly cited.[3]

NatureServe – For U.S information on biodiversity loss, NatureServe is the most credible and comprehensive source. NatureServe is a non-profit that collects data from a network of more than 60 governmental and non-governmental programs in the U.S. and Canada.[4]

 

  1. IUCN Red List, Background & History. https://www.iucnredlist.org/about/background-history [“Established in 1964, the International Union for Conservation of Nature’s Red List of Threatened Species has evolved to become the world’s most comprehensive information source on the global extinction risk status of animal, fungus and plant species.”]
  2. WWF (2024) Living Planet Report 2024 – A System in Peril. WWF, Gland, Switzerland, ISBN: 978-2-88085-319-8. [Note: Their flagship publication is released every two years – a comprehensive study of trends in global biodiversity and the health of the planet.]
  3. IPBES (2019) Global assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Brondízio, E. S., et al., (eds). IPBES secretariat, Bonn, Germany. ISBN: 978-3-947851-20-1.
  4. NatureServe (2023) Biodiversity in Focus: United States Edition. NatureServe: Arlington, VA, p. 4. [“For nearly 50 years, NatureServe has developed data and methods to comprehensively assess the conservation status of North American plant and animal species. As the authoritative source for data on U.S. and Canadian biodiversity, NatureServe is uniquely suited to answer questions about species and ecosystems and the extent to which they are threatened.”]

The IUCN Red List (International Union for the Conservation of Nature) estimates that of the many terrestrial, freshwater, and marine species assessed, about 28% are currently threatened with extinction.[1,2]

 

  1. IUCN Red List Summary Statistics – Tables 1a and 1b: Numbers of threatened species by major groups of organisms (1996–2024) https://www.iucnredlist.org/resources/summary-statistics [Of 166,061 assessed species, 46,337 are deemed to be “Threatened with Extinction”, i.e., meeting IUCN’s quantitative thresholds for “Critically Endangered, Endangered, or Vulnerable.”]
  2. For an analysis of the “9 categories of extinction risk” within IUCN’s “threatened species” see, Hannah Ritchie (2023) What does it mean for a species to be at risk of extinction? Published online at OurWorldinData.org. Retrieved from: ‘https://ourworldindata.org/extinction-risk-definition’ [Online Resource]

IPBES Global Assessment – The 2019 IPBES assessment concluded that, “The global rate of species extinction is already at least tens to hundreds of times higher than the average rate over the past 10 million years and is accelerating…”[1]

World Wildlife Fund – The WWF 2024 Living Planet Index has estimated a 73% decline in the average size of monitored wildlife populations between 1970 and 2020.[2]

IPBES Nexus Report – The IPBES 2024 report on “interlinkages” states that “for the last 30-50 years, all of the assessed indicators show biodiversity declines of between 2 to 6 per cent per decade.”[3]

Planetary Boundaries Research – Scientists have assessed that biodiversity loss is one of the planetary boundaries that have been definitively overstepped. Six of the nine boundaries are transgressed, “suggesting that Earth is now well outside of the safe operating space for humanity.”[4]

 

  1. IPBES (2019) Global assessment report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Brondízio, E. S., et al., (eds). IPBES secretariat, Bonn, Germany. ISBN: 978-3-947851-20-1, p. 24.
  2. WWF (2024) Living Planet Report 2024 – A System in Peril. WWF, Gland, Switzerland, p. 7. [“Over the past 50 years (1970–2020), the average size of monitored wildlife populations has shrunk by 73%, as measured by the Living Planet Index (LPI). This is based on almost 35,000 population trends and 5,495 species of amphibians, birds, fish, mammals and reptiles. Freshwater populations have suffered the heaviest declines, falling by 85%, followed by terrestrial (69%) and marine populations (56%).”] For an analysis of common misunderstandings of this data, see: Hannah Ritchie (October 2024) Living Planet Index: what does it really mean? Published online at OurWorldinData.org. Retrieved from: https://ourworldindata.org/living-planet-index-decline]
  3. Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) (Dec. 2024) Interlinkages Among Biodiversity, Water, Food and Health: Summary for Policymakers, p. 5.
  4. Richardson, K., et al., (2023). Earth beyond six of nine planetary boundaries. Science advances, 9(37), eadh2458, Abstract.

Biodiversity loss threatens the ongoing provision of food, clean water, physical and mental health, and safety.[1,2] Some of the practical benefits to human society of maintaining high levels of biodiversity:

Water quality – Ecosystems with higher levels of biodiversity are more efficient at removing excess nutrients from soil and water and thereby minimize nutrient pollution.[3,4]

Flood & drought control – Biodiversity plays a key role in maintaining the stability of wetlands, which in turn are pivotal in the protection against natural disasters like flood, drought, and wildfire.[5-7]

Soil health – Soil health is dependent on microbial and plant diversity. A “lack of biodiversity severely limits the potential of any cropping system and increases disease and pest problems.”[8] Long-term monoculture cropping systems, such as corn and soybeans, decrease soil health and the retention of organic matter, both of which impact future ability to grow food and reduce net CO2 emissions.[9,10]

Pollination – According to the USDA, “More than 150 food crops in the U.S. depend on pollinators, including almost all fruit and grain crops.”[11] Bees and other pollinators pollinate approximately 75% of the fruits, nuts and vegetables grown in the U.S.[12]

 

  1. Pereira, H. M., et al., (2012). Global biodiversity change: the bad, the good, and the unknown. Annual review of environment and resources, 37(1), 25-50, p. 26. [“Biodiversity provides the foundation for ecosystem services, including nutrient cycling, climate regulation, food production, and the regulation of the water cycle, and it is therefore intimately linked with human well-being.”]
  2. Marselle, M. R., et al., (2021). Pathways linking biodiversity to human health: A conceptual framework. Environment international, 150, 106420. [A compendium of human health impacts: “Four domains of pathways—both beneficial as well as harmful—link biodiversity with human health: (i) reducing harm (e.g. provision of medicines, decreasing exposure to air and noise pollution); (ii) restoring capacities (e.g. attention restoration, stress reduction); (iii) building capacities (e.g. promoting physical activity, transcendent experiences); and (iv) causing harm (e.g. dangerous wildlife, zoonotic diseases, allergens).” Abstract]
  3. Cardinale, B. J. (2011). Biodiversity improves water quality through niche partitioning. Nature (London), 472(7341), 86. [“One implication is that biodiversity may help to buffer natural ecosystems against the ecological impacts of nutrient pollution.” Abstract]
  4. Brisson, J., et al., (2020). Plant diversity effect on water quality in wetlands: a meta-analysis based on experimental systems. Ecological Applications, 30(4), 1–12, p. 5.  [“Overall, our meta-analysis suggests that plant richness does have a low but positive effect on COD (chemical oxygen demand) and TN (total nitrogen) removal and marginally on TP (total phosphorous) removal.”]
  5. Song, A., et al., (2024). Effects of biodiversity on functional stability of freshwater wetlands: a systematic review. Frontiers in Microbiology, 15, 1397683–1397683.
  6. Mitsch, W. J., et al., (2015). Ecosystem services of wetlands. International Journal of Biodiversity Science, Ecosystem Services & Management, 11(1), 1-4, p. 1. [Wetlands “stabilize water supplies, thus mitigating both floods and drought. They have been found to cleanse polluted waters, protect shorelines, and recharge groundwater aquifers… Wetlands continue to be cited as the most valuable parts of our landscape in ecosystem service assessments.”]
  7. Lang, M.W., et al., (2024). Status and Trends of Wetlands in the Conterminous United States 2009 to 2019. U.S. Department of the Interior; Fish and Wildlife Service, Washington, D.C., p. 9. [The loss of wetlands “reduces the prosperity, health, and safety of communities. This occurs through increased susceptibility of people and infrastructure to natural disasters like flood, drought, and wildfire, as well as decreased food security, reduction in clean water, increased harmful algal blooms and related increases in toxins and oxygen depleted ‘dead zones,’ greater vulnerability to sea level rise and storms, and reduced recreational opportunities.”]
  8. USDA National Resources Conservation Service, Soil Health Management. https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health [“Biodiversity is ultimately the key to the success of any agricultural system.”]
  9. Burian, A., et al., (2024). Biodiversity–production feedback effects lead to intensification traps in agricultural landscapes. Nature Ecology & Evolution, 8(4), 752-760, p. 752. [“However, these increases (in conventional food production) came at the cost of substantial reductions in local biodiversity and associated ecosystem functions, which can result in a strong negative feedback on yields (that is, productivity) and total agricultural production.”]
  10. Nunes, M. R. et al., (2018). No-till and cropping system diversification improve soil health and crop yield. Geoderma, 328, unu30–43, p. 31. [“Increases in biological diversity by introducing cover and perennial rotation crops may enhance soil health and thereby increase the viability of NT (no-till) systems.”]
  11. USDA Forest Service, Why is Pollination Important?
  12. USDA (July 17, 2018) NIFA-Funded Research Aims to Keep Bees on the Job.
    https://www.usda.gov/about-usda/news/blog/2018/07/17/nifa-funded-research-aims-keep-bees-job
    [“…about 75 percent of specialty crops depend on the services of pollinators of which bees are the most economically important.” Specialty crops are defined by the USDA as “Fruits and vegetables, tree nuts, dried fruits, horticulture, and nursery crops (including floriculture.)”]

Biodiversity Loss Figures