This topic will cover the basic concepts of climate change, including the greenhouse effect, global warming, and the impact of human activities on the Earth's climate system.
Introduction to Climate Change
(A concise, easy‑to‑read overview for students and anyone new to the topic)
| Term | Definition |
|---|---|
| Climate | Long‑term patterns of temperature, precipitation, wind, and other atmospheric variables (typically averaged over 30 + years). |
| Weather | Short‑term atmospheric conditions (hours to days). |
| Climate Change | A measurable shift in the average state of the climate system, or its variability, over periods ranging from decades to millions of years. |
| Global Warming | The specific aspect of climate change that refers to the rise in Earth’s average surface temperature, primarily due to human activities. |
| Source | Main Greenhouse Gases (GHGs) | Typical Emissions |
|---|---|---|
| Fossil‑fuel combustion | CO₂, CH₄, N₂O | Power plants, transport, industry |
| Agriculture & livestock | CH₄, N₂O | Enteric fermentation, rice paddies, fertilizer use |
| Deforestation & land‑use change | CO₂ | Forest clearing, soil disturbance |
| Industrial processes | HFCs, PFCs, SF₆ | Refrigerants, electronics, metal production |
Result: Concentrations of CO₂ have risen from ~280 ppm pre‑industrial to >420 ppm today, trapping more infrared radiation and warming the planet.
Key gases: CO₂, CH₄, N₂O, water vapor (feedback), and synthetic gases (HFCs, etc.).
| Indicator | Recent Trend (≈ last 50 yr) | Typical Consequence |
|---|---|---|
| Global mean surface temperature | +1.2 °C relative to 1850‑1900 | Heatwaves, altered ecosystems |
| Sea level | +20 cm (global average) | Coastal flooding, saltwater intrusion |
| Arctic sea‑ice extent | ~‑13 % per decade | Habitat loss, albedo feedback |
| Ocean heat content | ↑ ~ 30 % in upper 200 m | Coral bleaching, marine species shift |
| Extreme weather events | ↑ frequency/intensity of heatwaves, heavy precipitation, droughts | Economic losses, human health risks |
| Phenology (timing of biological events) | Earlier flowering, migration | Mismatch in food webs |
| Feedback Type | Positive (amplifying) | Negative (dampening) | |---------------