The Sixth Mass Extinction is Driven by Humans
- At the core of the biodiversity crisis is the exponential growth of the human population, now nearing 8 billion, up from less than 2 billion in 1920.
- This growth amplifies:
- Demand for resources (e.g., food, water, and energy).
- Space consumption, leading to urban sprawl and deforestation.
- Industrial activity, which depletes ecosystems and accelerates pollution.
Although population growth itself is neutral, its associated activities amplify specific threats to biodiversity.
Direct Causes of Biodiversity Loss
1. Over-Exploitation: Unsustainable Use of Resources
- Hunting and fishing: Species such as the Atlantic bluefin tuna and the African elephant face drastic declines due to overfishing and poaching.
- Deforestation for timber: Over-harvesting of keystone tree species disrupts forest ecosystems, threatening dependent species.
- Medicinal and ornamental plant trade: Unsustainable harvesting leads to population declines of species like wild orchids.
Many students mistakenly believe that only large-scale commercial activities threaten biodiversity. In reality, even small-scale, unsustainable practices can have devastating effects when repeated over time.
2. Habitat Loss: Urbanization and Agriculture
- Urbanization: Since 1992, urban areas have doubled, replacing natural habitats with cities and infrastructure.
- Agricultural expansion: Over 13 billion hectares of forests and wetlands have been converted into farmland.
The Amazon rainforest, home to immense biodiversity, is being cleared for soy and cattle farming.
TipWhen studying habitat loss, remember that it often leads to "edge effects," where the remaining habitat becomes fragmented and less suitable for species that require large, continuous areas.
