Threats to Life on Earth

📚 Key Concepts

🔹 The Triple Planetary Crisis

Modern human activities threaten Earth’s delicate balance through three major challenges:

image

1. Climate Change

Causes:

  • Burning fossil fuels (coal, oil, gas)
  • Deforestation reducing COâ‚‚ absorption
  • Industrial processes releasing greenhouse gases
  • Agriculture producing methane

Greenhouse Gases:

  • Carbon dioxide (COâ‚‚): 76% of emissions
  • Methane (CHâ‚„): 16% of emissions
  • Nitrous oxide (Nâ‚‚O): 6% of emissions
  • Fluorinated gases: 2% of emissions

Effects:

  • Global temperature rise (already +1.1°C since 1880)
  • Melting ice caps and glaciers
  • Rising sea levels
  • Extreme weather events
  • Shifts in precipitation patterns
  • Ecosystem disruption

2. Biodiversity Loss

Causes:

  • Habitat destruction for agriculture and cities
  • Pollution contaminating ecosystems
  • Overfishing and hunting
  • Climate change altering habitats
  • Invasive species disrupting ecosystems

Consequences:

  • Species extinction (1,000-10,000 times natural rate)
  • Ecosystem collapse
  • Loss of pollination services
  • Reduced food security
  • Loss of potential medicines

3. Pollution

Air Pollution:

  • Particulate matter (PM2.5, PM10)
  • Nitrogen oxides (NOâ‚“)
  • Sulfur dioxide (SOâ‚‚)
  • Carbon monoxide (CO)
  • Ozone at ground level

Water Pollution:

  • Industrial chemicals and heavy metals
  • Agricultural runoff (fertilizers, pesticides)
  • Plastic waste and microplastics
  • Sewage and untreated wastewater
  • Oil spills

Soil Pollution:

  • Chemical contamination
  • Excessive fertilizer use
  • Pesticide accumulation
  • Industrial waste disposal
  • Plastic contamination

🔹 Impact on Earth’s Systems

image

Atmosphere Changes:

  • Increased greenhouse gas concentrations
  • Ozone layer depletion (recovering due to Montreal Protocol)
  • Air quality degradation
  • Acid rain formation

Hydrosphere Changes:

  • Ocean acidification from COâ‚‚ absorption
  • Water temperature rise
  • Pollution of freshwater sources
  • Microplastic contamination

Geosphere Changes:

  • Soil degradation and erosion
  • Mineral resource depletion
  • Landscape modification
  • Waste accumulation

Biosphere Changes:

  • Species extinction and endangerment
  • Ecosystem fragmentation
  • Food web disruption
  • Reduced genetic diversity