2.6 Climate change: Describe the causes and effects of global climate change.

2. The natural environment

2.6 Climate change: Causes and Effects

🌍 Climate change is the long‑term shift in Earth’s weather patterns. Think of the planet as a giant blanket that keeps us warm. When the blanket gets thicker, it traps more heat, just like a heavy duvet keeps you warm at night. The main reason the blanket is getting thicker is the rise in greenhouse gases (GHGs) from human activities.

Causes of Global Climate Change

• 🚜 Fossil fuel combustion – burning coal, oil and gas for electricity, transport and industry releases large amounts of CO₂.
• 🌲 Deforestation – trees absorb CO₂; cutting them down reduces this natural “carbon sink.”
• 🏭 Industrial processes – cement production, metal smelting, and chemical manufacturing emit CO₂, CH₄ and N₂O.
• 🐄 Agriculture – livestock produce methane (CH₄) and rice paddies release nitrous oxide (N₂O).
• 💡 Waste management – landfills generate methane when organic waste decomposes anaerobically.

Effects of Global Climate Change

1. 🌡️ Rising temperatures – average global temperatures are increasing, leading to heatwaves and altered weather patterns.
2. 🌊 Melting ice and sea‑level rise – glaciers and ice sheets shrink, causing coastal erosion and flooding.
3. 🌪️ More extreme weather – stronger cyclones, intense rainfall, and prolonged droughts become more common.
4. 🌱 Shifts in ecosystems – species migrate to cooler areas, disrupting food webs and biodiversity.
5. 💧 Water scarcity – changes in precipitation patterns reduce freshwater availability for communities and agriculture.

Key Data: Greenhouse Gas Emissions by Sector (2023)

Sector	CO₂ (Mt)	CH₄ (Mt)	N₂O (Mt)
Energy (electricity & heat)	35.0	0.2	0.1
Transport	25.0	0.1	0.0
Industry	15.0	0.3	0.2
Agriculture & Forestry	5.0	2.5	1.0
Waste	2.0	1.8	0.3

Mathematical Insight: The Greenhouse Effect

The basic relationship can be expressed as: $$ T_{\text{surface}} = \left( \frac{S (1 - \alpha)}{4 \sigma (1 - \varepsilon)} \right)^{1/4} $$ where:

• $S$ = solar constant (≈1361 W m⁻²)
• $\alpha$ = planetary albedo (≈0.3)
• $\sigma$ = Stefan‑Boltzmann constant (5.67 × 10⁻⁸ W m⁻² K⁻⁴)
• $\varepsilon$ = atmospheric emissivity (increases with GHGs)

Increasing $\varepsilon$ (more greenhouse gases) reduces the denominator, raising $T_{\text{surface}}$ – just like adding more blankets keeps you warmer.

What Can We Do?

• 🚗 Switch to electric or hybrid vehicles.
• 🌱 Plant trees – they absorb CO₂.
• ♻️ Reduce, reuse, recycle to cut waste emissions.
• 💡 Use energy‑efficient appliances and LED lighting.
• 📚 Spread awareness – the more people know, the stronger the action.

Remember: every small change adds up, just like each thread strengthens a blanket. Together, we can keep our planet comfortable for future generations. 🌟