Global warming refers to the long-term increase in Earth's average surface temperature due to human activities, primarily the emission of greenhouse gases. It is the most prominent aspect of broader climate change, which encompasses all long-term shifts in weather patterns and temperatures.

The Natural Greenhouse Effect

The Earth's atmosphere naturally contains certain gases that trap heat, a process vital for life on Earth. This is called the Greenhouse Effect.

• Sunlight (shortwave radiation) passes through the atmosphere and warms the Earth's surface.
• The Earth's surface then radiates some of this energy back as infrared (longwave) radiation.
• Naturally occurring greenhouse gases in the atmosphere absorb some of this outgoing infrared radiation, preventing it from escaping directly into space.
• This trapped heat warms the planet, making it habitable (average temperature around +15°C instead of -18°C).

Enhanced Greenhouse Effect and Global Warming

Human activities have significantly increased the concentration of greenhouse gases in the atmosphere, leading to an "enhanced" or "anthropogenic" greenhouse effect. This additional trapping of heat is the primary cause of global warming.

Key Greenhouse Gases (GHGs) and Their Sources

These gases differ in their ability to trap heat (Global Warming Potential - GWP) and how long they remain in the atmosphere.

• Carbon Dioxide (CO₂):
  • Source: Burning fossil fuels (coal, oil, natural gas) for energy, transportation, and industry; deforestation (trees absorb CO₂).
  • Significance: Most significant contributor to global warming due to its high volume and long atmospheric lifetime.
• Methane (CH₄):
  • Source: Livestock digestion (enteric fermentation), rice cultivation, landfills, natural gas leakage.
  • Significance: Much higher GWP than CO₂ over a shorter period.
• Nitrous Oxide (N₂O):
  • Source: Agricultural activities (fertilizers), burning fossil fuels, industrial processes.
  • Significance: Very potent GHG with a long atmospheric lifetime.
• Fluorinated Gases (e.g., HFCs, PFCs, SF₆):
  • Source: Industrial processes, refrigerants, aerosols.
  • Significance: Extremely high GWPs, though present in smaller concentrations.
• Water Vapor (H₂O):
  • Significance: The most abundant natural greenhouse gas. Its concentration is influenced by temperature (warmer air holds more water vapor), creating a positive feedback loop (warming leads to more water vapor, which leads to more warming).

Causes of Global Warming

• Burning of Fossil Fuels: The largest source of CO₂ emissions from power generation, transportation, and industrial processes.
• Deforestation: Reduces the amount of CO₂ absorbed from the atmosphere by trees, and releases stored carbon when trees are burned or decompose.
• Agriculture: Livestock (methane), rice paddies (methane), and nitrogen-based fertilizers (nitrous oxide) contribute significantly.
• Industrial Processes: Release various GHGs, including fluorinated gases.
• Landfills: Decomposing organic waste produces methane.

Impacts of Global Warming (Consequences of Climate Change)

The rising global temperature leads to a cascade of environmental and societal changes:

• Rising Global Temperatures: Leads to more frequent and intense heatwaves.
• Melting Glaciers and Ice Caps: Contributes to sea level rise and reduces freshwater supplies.
• Sea Level Rise: Threatens coastal communities, leading to increased flooding and displacement.
• More Frequent and Intense Extreme Weather Events: Such as droughts, floods, wildfires, and tropical storms.
• Ocean Acidification: Oceans absorb excess CO₂, becoming more acidic, which harms marine life (especially shell-forming organisms).
• Impacts on Ecosystems and Biodiversity: Shifts in plant and animal ranges, species extinction, disruption of food webs.
• Impacts on Agriculture and Food Security: Changes in rainfall patterns, increased pests, and extreme weather reduce crop yields.
• Impacts on Human Health: Increased heat-related illnesses, spread of vector-borne diseases, respiratory problems due to air pollution.

Mitigation and Adaptation

Addressing global warming requires a two-pronged approach:

• Mitigation: Reducing greenhouse gas emissions (e.g., shifting to renewable energy, improving energy efficiency, afforestation).
• Adaptation: Adjusting to the unavoidable impacts of climate change (e.g., building sea walls, developing drought-resistant crops).

Understanding global warming is critical for developing effective strategies to protect our planet and future generations.

Written by Kasiban Parthipan