This topic introduces the concept of climate change, its causes, and the potential impacts it has on the environment and society.
Introduction to Climate Change
(A concise, easy‑to‑read overview for students or anyone new to the subject)
| Term | Meaning |
|---|---|
| Climate | The long‑term (30‑year+) average of temperature, precipitation, wind, etc., for a region. |
| Weather | Short‑term atmospheric conditions (hours‑days). |
| Climate Change | A statistically significant shift in the average state of the climate or its variability over periods of decades to millennia. |
| Global Warming | The observed rise in Earth’s average surface temperature, primarily caused by increased greenhouse gases (GHGs). |
Key point: Global warming is a driver of broader climate change, which includes changes in precipitation patterns, sea‑level rise, and extreme‑event frequency.
| Greenhouse Gas | Primary Sources | Atmospheric Lifetime |
|---|---|---|
| CO₂ (Carbon Dioxide) | Fossil‑fuel combustion, cement production, deforestation | Decades to centuries |
| CH₄ (Methane) | Agriculture (ruminants), landfills, natural gas systems | ~12 years |
| N₂O (Nitrous Oxide) | Fertilizer use, industrial processes | ~114 years |
| Fluorinated gases (e.g., HFCs) | Refrigerants, electronics | 10–10,000 years |
The Intergovernmental Panel on Climate Change (IPCC) estimates that human activities have produced a +2.3 W m⁻² radiative forcing (2021 data), driving the observed warming.
| Feedback | Effect on Climate | Example |
|---|---|---|
| Water‑vapor feedback | Positive | Warmer air holds more vapor → more greenhouse effect. |
| Ice‑albedo feedback | Positive | Melting ice reduces reflectivity → more solar absorption. |
| Carbon‑cycle feedback | Mixed | Permafrost thaw releases CO₂/CH₄ (positive). |
| Cloud feedback | Uncertain (both) | Changes in cloud type/altitude affect radiation. |
| Indicator | Observed Trend (1900‑2020) | Data Source |
|---|---|---|
| Global mean surface temperature | +1.1 °C ↑ | NASA GISS, NOAA |
| Ocean heat content | ↑ ~30 % in upper 200 m | ARGO floats |
| Sea‑level rise | 3.3 mm yr⁻¹ (average) | Satellite altimetry |
| Arctic sea‑ice extent (Sept) | ↓ ~13 % per decade | NSIDC |
| Glacial mass loss | Millions of gigatonnes lost | GRACE satellites |
| Extreme weather frequency |