A4.2.5 Evidence for a biodiversity crisis Notes

What Is the Biodiversity Crisis?

1. The biodiversity crisis refers to the accelerated loss of species, habitats, and genetic diversity due to human activities.
2. Unlike natural extinction events, which occur over millennia, today’s rates are extraordinary:
   1. Current extinction rate: 100–1,000 times higher than the natural background rate.
   2. At-risk species: Up to one million species are at risk of extinction in the coming decades.

How Do Scientists Measure Biodiversity Loss?

1. Biodiversity Metrics: Richness and Evenness

1. Scientists measure biodiversity using two main metrics:
   1. Species richness: The total number of species in a given area.
   2. Species evenness: The distribution of individuals among those species.

2. Long-Term Monitoring

1. Long-term studies track changes in species populations and ecosystem health over time.

Evidence from Global Studies

The IPBES Report

1. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) synthesizes data from global studies.
2. Key findings include:
   1. Wetlands: 85% lost since the 18th century.
   2. Coral reefs: Over 50% have been degraded since 1950.
   3. Pollinators: Declines threaten food security for 70% of major crops reliant on pollination.

The IUCN Red List

1. The International Union for Conservation of Nature (IUCN) maintains the Red List, tracking species extinction risk.
2. As of 2023:
   1. 41,000 species are threatened with extinction, including:
      1. 40% of amphibians.
      2. 34% of conifers.
      3. 25% of mammals.

The Role of Citizen Scientists

Citizen Contributions

1. Citizen scientists, volunteers collecting data, play a crucial role in biodiversity monitoring. Projects like:
   1. The Audubon Society’s Christmas Bird Count (over 120 years of data).
   2. iNaturalist, where users photograph and identify species with the help of AI.

Strengths and Challenges

1. Strengths: Citizen science expands data collection to inaccessible or under-monitored regions.
2. Challenges: Data quality and consistency vary. Validation by professionals ensures reliability.

Technological Advances in Biodiversity Monitoring

1. Satellite Imaging: Satellites like Sentinel-2 track habitat changes such as deforestation and urbanization in real time.
2. AI and Machine Learning: AI-powered tools like eBird and iNaturalist enable rapid species identification and help analyze vast datasets.
3. Environmental DNA (eDNA: eDNA allows scientists to detect species from traces of DNA in water, soil, or air, revolutionizing the study of cryptic or elusive organisms.

Implications of the Biodiversity Crisis

1. Ecological Collapse
   1. The extinction of key species destabilizes ecosystems.
   2. Overfishing of predatory fish allows algal blooms, damaging coral reefs.
2. Economic Consequences
   1. Biodiversity loss jeopardizes industries like agriculture, forestry, and fisheries, which depend on ecosystem services.
3. Ethical Considerations
   1. Human-driven extinction raises ethical questions about our responsibility to other species.