Atmospheric Processes & Climate Change
Global circulation, weather systems, causes and effects of climate change
Global atmospheric circulation is driven by unequal heating of Earth's surface.
Three-cell model:
- Hadley cell (0-30°): Hot air rises at equator → moves poleward → sinks at 30° (subtropical high pressure)
- Ferrel cell (30-60°): Surface air moves poleward, meets polar air at polar front
- Polar cell (60-90°): Cold dense air sinks at poles
Climate change evidence: Rising global temperatures (~1.1°C since pre-industrial). Ice cores, sea level data, glacier retreat, shifting seasons.
Causes:
- Natural: Solar variation, volcanic eruptions, orbital changes (Milankovitch cycles)
- Human (enhanced greenhouse effect): CO₂ (fossil fuels), methane (agriculture), deforestation reduces CO₂ absorption
Effects: Sea level rise, extreme weather events, coral bleaching, permafrost melting, crop yield changes, biodiversity loss.
Responses:
- Mitigation: Reduce emissions (Paris Agreement, renewable energy, carbon tax)
- Adaptation: Sea walls, drought-resistant crops, early warning systems
Key Points to Remember
- 1Three-cell model: Hadley, Ferrel, Polar
- 2Enhanced greenhouse effect from human CO₂ emissions
- 3Evidence: ice cores, sea level, glacier retreat
- 4Mitigation reduces causes; adaptation manages effects
Pakistan Example
Pakistan's Climate Vulnerability — Floods, Heatwaves, and Glacial Melt
Pakistan contributes <1% of global emissions but ranks among the most climate-vulnerable countries. The 2022 floods (one-third of country submerged) were linked to enhanced monsoon rainfall from warming oceans. Glacial melt in Gilgit-Baltistan threatens water supply for millions. Pakistan's NCCP (National Climate Change Policy) is an adaptation response.
Quick Revision Infographic
Geography — Quick Revision
Atmospheric Processes & Climate Change
Key Concepts
Pakistan's Climate Vulnerability — Floods, Heatwaves, and Glacial Melt
Pakistan contributes <1% of global emissions but ranks among the most climate-vulnerable countries. The 2022 floods (one-third of country submerged) were linked to enhanced monsoon rainfall from warming oceans. Glacial melt in Gilgit-Baltistan threatens water supply for millions. Pakistan's NCCP (National Climate Change Policy) is an adaptation response.