📖 In-Depth Theory
The Greenhouse Effect
The GREENHOUSE EFFECT is the natural process that keeps the Earth warm enough to support life.
HOW IT WORKS:
1. Short-wave radiation (visible light and UV) from the Sun passes through the atmosphere and warms the Earth's surface.
2. The Earth's surface emits INFRARED (heat) radiation back upward.
3. GREENHOUSE GASES in the atmosphere ABSORB this infrared radiation and re-emit it in all directions — including back towards Earth.
4. This traps heat and warms the Earth — without it, Earth would be approximately −18°C.
GREENHOUSE GASES include:
WATER VAPOUR (H₂O) — biggest natural greenhouse gas.
CARBON DIOXIDE (CO₂) — from combustion, respiration, deforestation.
METHANE (CH₄) — from livestock, landfill, natural gas leaks, wetlands.
NITROUS OXIDE (N₂O) — from agriculture, fertilisers.
Without the greenhouse effect: Earth would be too cold for life.
With TOO MUCH greenhouse effect: global warming → climate change.
Human Activities Increasing Greenhouse Gases
Human activities are INCREASING greenhouse gas concentrations beyond natural levels:
CARBON DIOXIDE (CO₂):
BURNING FOSSIL FUELS — coal, oil, natural gas release CO₂ locked underground for millions of years.
DEFORESTATION — trees absorb CO₂; removing them reduces absorption AND releases stored carbon when burned or decomposed.
CEMENT PRODUCTION — CaCO₃ → CaO + CO₂ (decomposition releases CO₂).
METHANE (CH₄):
LIVESTOCK (cattle and sheep) — produce methane during digestion (enteric fermentation).
LANDFILL SITES — decomposition of organic waste under anaerobic conditions produces methane.
RICE PADDIES — anaerobic decomposition in flooded fields.
NATURAL GAS LEAKS from extraction and distribution.
NITROUS OXIDE (N₂O):
NITROGEN FERTILISERS — bacteria convert excess fertiliser to N₂O.
AGRICULTURAL SOILS.
Global Climate Change and Carbon Footprint
GLOBAL CLIMATE CHANGE:
Rising greenhouse gas levels increase the greenhouse effect → GLOBAL WARMING — rising average global temperatures.
EFFECTS of climate change:
MELTING ICE CAPS AND GLACIERS → rising sea levels → coastal flooding.
MORE EXTREME WEATHER — stronger storms, more intense rainfall, droughts.
HABITAT LOSS — ecosystems disrupted, species extinction risk.
OCEAN ACIDIFICATION — CO₂ dissolves in seawater to form carbonic acid → threatens coral reefs and shellfish.
AGRICULTURAL DISRUPTION — changed growing seasons, droughts, flooding.
CARBON FOOTPRINT:
The total amount of greenhouse gases (measured as CO₂ equivalent) produced by an individual, organisation or product.
REDUCING CARBON FOOTPRINT:
Renewable energy (wind, solar, hydroelectric) instead of fossil fuels.
Improve energy efficiency (insulation, LED lighting, efficient vehicles).
Electric vehicles.
Plant trees (reforestation).
Reduce meat consumption (livestock produce methane).
Carbon capture and storage (CCS).
⚠️ Common Mistake
The greenhouse effect is NATURAL and NECESSARY — without it Earth would be frozen. The PROBLEM is ENHANCED greenhouse effect — human activities increasing greenhouse gas concentrations beyond natural levels, causing additional warming. Always distinguish between the natural greenhouse effect (beneficial) and the enhanced greenhouse effect (potentially harmful).