Global Change
What you must know
Understand the greenhouse effect and the enhanced greenhouse effect from CO₂, CH₄, N₂O, and CFCs, including relative global warming potential. Know evidence for climate change (ice cores, sea-level rise, temperature records, phenology shifts) and feedbacks (positive: permafrost methane release, ice-albedo; negative: increased plant growth). Study consequences: sea-level rise, ocean acidification (CO₂ + water → carbonic acid), coral bleaching, shifts in species ranges, and extreme weather. Learn mitigation (renewables, efficiency, carbon capture, sequestration) vs. adaptation (sea walls, drought-resistant crops). Know ozone depletion as a separate global change and the success of the Montreal Protocol. Understand invasive species and habitat fragmentation as global-change drivers.
Traps
- Confusing the greenhouse effect (natural, necessary) with the enhanced greenhouse effect (human-driven).
- Mixing mitigation (reduce cause) with adaptation (cope with effect).
- Treating ocean acidification as the same as warming - it is a chemical change from dissolved CO₂.
- Forgetting positive feedbacks amplify change while negative feedbacks dampen it.
Worked example / rule of thumb
Burning fossil fuels adds CO₂ → more heat trapped → warming → ice melt → lower albedo → more warming. Rule: identify whether a feedback amplifies (positive) or dampens (negative) the initial change.