6.2 Climate change - causes and impact

Climate

Climate is the average weather conditions of a region over long periods (typically 30 years or more), including temperature, precipitation, humidity, and wind. The main factors impacting the climate in ana rea are the seasonal variation in temperature and precipitation.

Anthropogenic CO₂ Emissions

Major Sources of Anthropogenic CO₂ Emissions

• Fossil Fuel Combustion:
  • Sectors: Energy production (coal, oil, natural gas), transportation, and industrial manufacturing.
  • Impact: Responsible for ~75% of total global CO₂ emissions.
• Deforestation and Land Use Changes:
  • Trees store carbon; cutting and burning forests release CO₂.
  • Conversion of forests to agriculture or urban areas reduces carbon sequestration capacity.
• Industrial Processes:
  • Cement production releases CO₂ during the chemical transformation of limestone.
  • Steel and aluminium industries also emit large amounts of CO₂.
• Agriculture:
  • Clearing land for farming increases emissions.
  • Methane (from livestock) and nitrous oxide (from fertilizers) also contribute to overall greenhouse gas emissions.
• Waste Management:
  • Decomposition of organic waste in landfills produces methane and CO₂.

Trends in Anthropogenic CO₂ Emissions

CO₂ levels have increased from ~280 ppm (pre-industrial levels) to over 420 ppm today. The Industrial Revolution marked a sharp rise in emissions due to reliance on coal and oil.

Correlation Between CO₂ and Global Temperatures

How They Are Linked:

• CO₂ is a greenhouse gas that traps heat in the atmosphere.
• As CO₂ levels increase, more heat is retained, leading to higher global temperatures.

Evidence:

• Ice core records show a strong correlation between CO₂ concentrations and historical temperature fluctuations.
• Current warming trends align with increasing anthropogenic CO₂ emissions.

Climate change

The greenhouse effect has been enhanced by anthropogenic emissions of GHGs. This has led to global warming and, therefore, climate change.

Impact of Climate Change on Ecosystems

• Polar Ecosystems:
  • Melting ice caps and glaciers reduce habitat for polar bears, seals, and penguins.
  • Thawing permafrost releases trapped methane, exacerbating warming.
• Marine Ecosystems:
  • Coral bleaching due to rising sea temperatures.
  • Ocean acidification from absorbed CO₂ harms shellfish and plankton.
• Forests:
  • Increased frequency of wildfires.
  • Shift in species ranges, with some plants and animals unable to adapt quickly enough.
• Grasslands and Deserts:
  • Desertification due to prolonged droughts.
  • Loss of biodiversity in grasslands.

Impact of Climate Change on Human Societies

• Health:
  • Increased heatwaves, spreading vector-borne diseases (e.g., malaria, dengue).
  • Respiratory issues due to worsened air quality.
• Food Security: