Loss of Biodiversity

Think of biodiversity as the “insurance policy” of life on Earth. The more diverse our ecosystems and species, the more resilient nature is. But today, this insurance is shrinking at a frightening pace. This shrinking—this decline in the number and variety of species—is what we call Biodiversity Loss.

What Is Biodiversity Loss?

Biodiversity loss means:

• Reduction in species richness
• Loss of genetic variability
• Decline in variety of species
• Degradation of ecosystem diversity

It occurs at multiple levels:

• Within a species
• Within an ecosystem
• Across a geographical area

This loss weakens ecological stability and threatens human survival.

Evidence of Biodiversity Loss (IUCN Red List)

According to the IUCN Red List (2004):

• 784 species have gone extinct in the last 500 years.

Some well-known examples:

• Passenger Pigeon
• Steller’s Sea Cow
• Three extinct tiger subspecies:
  • Bali Tiger
  • Javan Tiger
  • Caspian Tiger

Mass Extinctions – The Sixth One Has Begun

Life on Earth has existed for more than 3 billion years, and during this long history, there have been five natural mass extinctions.

But today, we are living through the Sixth Extinction—and unlike earlier events, this one is anthropogenic (caused by humans).

Scientists estimate:

• Species extinction is now 100 to 1,000 times faster than natural background rates.
• If current trends continue, half of all species could disappear within the next 100 years.

This makes biodiversity loss one of the greatest existential threats of our time.

The IPBES Global Assessment Report (2019)

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) released a landmark report in 2019.

Key findings:

• Total estimated species on Earth: 8 million
  (including 5.5 million insect species)
• Up to 1 million species are at risk of extinction—within decades.
• The threatened groups include:
  • 40% of amphibians
  • 33% of reef-forming corals
  • More than one-third of all marine mammals

This is the most comprehensive biodiversity assessment ever done at the global level.

What Is IPBES?

• Headquartered in Bonn, Germany
• Has 130 member countries, including India
• Works like the IPCC, but for biodiversity & ecosystem services
• Compiles, reviews, and assesses scientific literature

IPBES prepared the Global Assessment Report 2019, sponsored by the United Nations.

Major Findings from the IPBES 2019 Report

These findings clearly show how human activity has dramatically reshaped Earth’s natural systems:

1. Nearly 50% of natural ecosystems have vanished.

2. Humans have drastically altered:

• 75% of land ecosystems
• 40% of marine systems
• 50% of inland water bodies

3. Key trends since 1970:

• 300% increase in global food crop production
• >100% increase in urban areas since 1992
• 23% of land showing reduced productivity due to land degradation
• 50% of agricultural expansion replacing forests
• 16–21 cm rise in global sea level since 1900
• 100% increase in GHG emissions since 1980 → global temperature up by 0.7°C
• Plastic pollution increased tenfold since 1980

4. Coastal Risk

• 100–300 million people living in coastal regions face heightened risk due to loss of coastal ecosystems like mangroves and coral reefs.

5. Mining

• Occupies <1% of land area
• But has disproportionately high negative impacts

6. Environmental Activists at Risk

• Over 1,000 environmental activists and journalists were killed (2002–2013) while reporting ecological issues.

This reflects the socio-political dimension of biodiversity loss.

Living Planet Report 2024 (WWF)

What is the Living Planet Report?

The Living Planet Report uses a tool called the Living Planet Index (LPI) to monitor wildlife population trends.

• Prepared using data from the Zoological Society of London (ZSL).
• Tracks 35,000 vertebrate populations from 5,495 species.
• Serves as an early warning system to identify extinction risks and ecosystem health.

Just as an ECG monitors the heart’s condition, the LPI monitors the planet’s ecological heartbeat.

The Living Planet Report is released every two years by the World-Wide Fund for Nature

According to this report: Between 1970 and 2020, humanity has witnessed a catastrophic 73% decline in the average size of monitored wildlife populations. This means that if we had 100 animals in 1970 (across mammals, birds, amphibians, reptiles, and fish), today only about 27 remain.

Where is the Decline the Worst?

WWF notes that the decline is not uniform:

• Freshwater ecosystems → 85% decline
  (the fastest disappearing ecosystems on Earth)
• Terrestrial ecosystems → 69% decline
• Marine ecosystems → 56% decline

Freshwater spaces—rivers, lakes, wetlands—are disappearing due to pollution, dam construction, invasive species and unsustainable water extraction, making them the most threatened systems.

Severe Population Declines

The steepest falls are seen in:

• Latin America & Caribbean → 95% decline
• Africa → 76%
• Asia–Pacific → 60%
• Freshwater ecosystems → 85%

This is alarming because these regions and ecosystems are biodiversity strongholds.

The State of the World’s Birds (BirdLife International)

Global Bird Status:

• 48% of bird species are declining
• 39% stable
• 6% increasing
• 7% unknown
• 1 in 8 species is threatened with extinction

Indian Bird Assessment:

Out of 867 assessed Indian bird species:

• 80% declining
• 6% stable
• 14% increasing
• Forest-dependent birds are declining the most
• Followed by birds dependent on grasslands and wetlands

This is a major ecological warning.

Trophic Cascade

A trophic cascade occurs when the removal or decline of a species at one trophic level leads to a series of dramatic effects across the ecosystem—affecting other species and ecological processes.

Example:

If a top predator disappears, herbivore populations explode → vegetation declines → soil quality degrades → entire ecosystem collapses.

This shows how interconnected—and fragile—ecosystems truly are.