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What is Climate Change?

What is Climate Change?

Climate change refers to long-term alterations in global temperatures and weather patterns. While Earth's climate has always changed naturally, the current rapid changes are unequivocally caused by human activities.

  • Primary Cause: The burning of fossil fuels (coal, oil, gas) since the Industrial Revolution. This marked a shift from using "current sunlight" (like wood) to "ancient sunlight" stored as carbon.
  • The Mechanism (Intensified Greenhouse Effect):
    1. Burning fossil fuels releases Greenhouse Gases (GHGs) like Carbon Dioxide ($CO_2$), Methane ($CH_4$), and Nitrous Oxide ($N_2O$).
    2. These gases accumulate in the atmosphere and act like a thicker blanket, trapping excess heat that would otherwise escape into space.
    3. This trapping of additional heat leads to a rise in the Earth's average temperature, a phenomenon known as global warming.

Climate Feedback Loops & Tipping Points

The climate is a complex system with "feedback loops" that can amplify initial warming, creating a risk of irreversible changes.

  • Definition: A feedback loop is a process where an initial change in the climate system leads to a secondary change that either reinforces the original change (positive feedback) or dampens it (negative feedback). Climate change is dominated by dangerous positive feedback loops.
  • Key Examples of Positive Feedback Loops:
    • Melting Ice (Albedo Effect): Bright white ice reflects sunlight. As it melts, it exposes darker ocean or land, which absorbs more heat, causing even more ice to melt.
    • Thawing Permafrost: Frozen soil in the Arctic (permafrost) stores vast amounts of methane. As the planet warms, the permafrost thaws, releasing this potent GHG, which in turn causes more warming.
  • Tipping Points: These are critical thresholds which, when crossed, could trigger irreversible and cascading changes in the climate system, as activist Greta Thunberg warns.

Mitigation vs. Adaptation: The Two-Pronged Approach

These are the two fundamental strategies for addressing climate change. It is crucial to understand their differences.

Feature Mitigation Adaptation
Focus Tackling the CAUSES of climate change. Managing the EFFECTS (impacts) of climate change.
Goal To reduce or prevent GHG emissions. To adjust systems to minimize harm from climate impacts.
Scale Primarily Global. Primarily Local or Regional.
Timeframe Benefits are primarily Long-term. Benefits are Immediate to Long-term.
Examples • Shifting to renewable energy (solar, wind)
• Reforestation
• Increasing energy efficiency
• Sustainable agriculture		 • Building sea walls
• Developing drought-resistant crops
• Early warning systems
• Climate-resilient infrastructure

The Scientific Consensus (IPCC)

  • The Intergovernmental Panel on Climate Change (IPCC), in its Sixth Assessment Report, states with high confidence that human activities have unequivocally caused global warming.
  • It notes that global surface temperatures have risen faster since 1970 than in any other 50-year period in at least the last 2,000 years.

Exam Tip: The Mitigation vs. Adaptation table is the most important part of this lecture. Be prepared to define, differentiate, and provide clear examples for both strategies. Understanding the concept of positive feedback loops (especially melting ice and permafrost) is also essential for demonstrating a deeper knowledge of climate science.

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