What are Greenhouse Gases? (SL IB Environmental Systems & Societies (ESS))

What are Greenhouse Gases?

• Human activities are significantly contributing to the increase in greenhouse gases in the atmosphere, leading to various impacts on the Earth's climate system
  • Increased levels of carbon dioxide, methane, and water vapour result from human activities such as burning fossil fuels, deforestation, and industrial processes

Sources of Greenhouse Gases

• Carbon dioxide:
  • Main sources include the combustion of fossil fuels for energy generation, transportation, and industrial processes
  • Deforestation and land-use changes, such as clearing forests for agriculture or urbanisation, contribute to CO₂ emissions indirectly by reducing the planet's capacity to absorb carbon dioxide through photosynthesis

• Methane:
  • Produced by natural processes like the decomposition of organic matter in wetlands, forests, and oceans
  • Human activities such as agriculture (particularly rice cultivation and livestock farming), coal mining, oil and gas extraction, and waste management (landfills) contribute to methane emissions

• Water vapour:
  • Water vapour is the most abundant greenhouse gas in the atmosphere and its concentration is primarily determined by temperature and humidity levels
  • While human activities do not directly emit water vapour as a greenhouse gas, they can indirectly influence its levels through activities that affect temperature and moisture, such as deforestation, land-use changes, and the burning of fossil fuels that release other greenhouse gases

Photo by Steve Douglas on Unsplash 

Rice paddies produce methane due to the anaerobic conditions created by flooded cultivation, which promote the growth of methane-producing microorganisms that decompose organic matter in the soil

Effects of Greenhouse Gases

• These greenhouse gases trap heat in the atmosphere, causing the Earth's temperature to rise, leading to global warming
  • The increase in mean global temperature has wide-ranging effects, including melting ice caps and glaciers, shifts in precipitation patterns, and changes in ecosystem dynamics
  • The higher concentration of greenhouse gases is contributing to the intensification of extreme weather events such as hurricanes, droughts, heatwaves, and heavy rainfall

• Long-term changes in climate and weather patterns occur as a result of the altered energy balance in the Earth's atmosphere and oceans
• Rising greenhouse gas levels also contribute to the thermal expansion of seawater and the melting of land-based ice, resulting in sea level rise
• The combination of increased global temperatures and rising sea levels poses significant risks to coastal communities, low-lying regions, and ecosystems
• It is essential to mitigate greenhouse gas emissions and implement strategies to adapt to the changing climate to minimise the potential impacts on the planet and human societies

The Enhanced Greenhouse Effect

• The enhanced greenhouse effect is different from the natural greenhouse effect because it is primarily driven by human activities that release excessive amounts of greenhouse gases into the atmosphere, leading to an intensified trapping of heat and subsequent global warming
• While the natural greenhouse effect is a necessary process that helps regulate the Earth's temperature by trapping some heat to maintain a habitable climate, the enhanced greenhouse effect disrupts this balance as a result of greenhouse gas concentrations being artificially increased beyond natural levels

Human activities lead to the emission of greenhouse gases that enhance the natural greenhouse effect, contributing to global warming