pollution-and-climate Stratospheric ozone (good) Tap / Space to flip
pollution-and-climate O₃ in 12-50 km layer; absorbs UV-B and UV-C. Depleted by CFCs/halons (Antarctic ozone hole).
Highest weight: 15–20%
Global Change
The single highest-weight unit. Stratospheric ozone, climate change, ocean acidification, invasive species. Spend extra time here.
Must-know content
- Stratospheric ozone depletion:
- UV cleaves Cl off CFC molecules; one Cl destroys ~100,000 O₃ molecules catalytically.
- Antarctic ozone hole forms each spring (cold polar stratospheric clouds catalyze the reaction).
- Montreal Protocol (1987) — phased out CFCs; widely successful, ozone now recovering.
- Climate change vs. weather: climate is long-term (decades+), weather is short-term.
- Greenhouse effect — GHGs absorb outgoing infrared radiation, warming the lower atmosphere. NATURAL and necessary; the ENHANCED effect is anthropogenic.
- Major GHGs and 100-yr GWP:
- CO₂ — GWP 1 (reference). From combustion, deforestation. Most abundant anthropogenic.
- CH₄ — GWP ~28-34. From livestock, landfills, rice paddies, fracking leaks.
- N₂O — GWP ~265-298. From synthetic fertilizer, combustion.
- CFCs / HFCs — GWP 1,000s-10,000s+. Legacy refrigerants and aerosols.
- Water vapor — large effect but a feedback, not directly forcing.
- Climate change consequences: sea-level rise (thermal expansion + melting ice), shrinking glaciers / ice sheets, intensified storms, droughts, range shifts, ocean acidification, coral bleaching.
- Ocean acidification: CO₂ + H₂O → H₂CO₃ → H⁺ + HCO₃⁻. Lowers pH, dissolves calcium-carbonate shells (corals, mollusks, plankton). Threatens marine food webs.
- Coral bleaching — heat-stressed corals expel symbiotic zooxanthellae and turn white; without algal photosynthesis they starve.
- Invasive species — non-native organisms that spread, outcompete natives, lack predators (zebra mussels, kudzu, Asian carp, brown tree snake).
- HIPPCO — drivers of biodiversity loss: Habitat destruction · Invasive species · Population growth · Pollution · Climate change · Overexploitation.
- Conservation: biodiversity hotspots, protected areas (parks, reserves), captive breeding, wildlife corridors, ESA, CITES.
- Major treaties:
- Montreal Protocol (1987) — CFC phase-out.
- Kyoto Protocol (1997) — GHG reductions; binding only on developed nations.
- Paris Agreement (2015) — voluntary NDCs; goal to keep warming "well below" 2 °C, ideally 1.5 °C.
Example questions
MCQ Which gas has the greatest warming impact PER MOLECULE on a 100-year timescale? (A) CO₂ (B) CH₄ (C) N₂O (D) CFC-12
Answer: D. CFCs have GWP in the thousands; CH₄ ≈ 28×; N₂O ≈ 265×. CO₂ is the reference (GWP = 1) and has the largest integrated impact only because it is far more abundant.
FRQ Explain the difference between stratospheric and tropospheric ozone, including whether each is harmful.
Answer: Stratospheric ozone (10-50 km altitude) is the "good" ozone layer. It absorbs harmful UV-B radiation, protecting life from skin cancer, cataracts, and DNA damage. It was depleted in the late 20th century by CFCs but is now recovering thanks to the Montreal Protocol. Tropospheric (ground-level) ozone is a "bad" secondary pollutant formed when NOx and VOCs react in sunlight. It irritates lungs, damages crops, and is a key component of photochemical smog. The two ozone phenomena are at different altitudes and have opposite effects on humans.
MCQ Which is the LEADING cause of biodiversity loss globally? (A) Climate change (B) Invasive species (C) Habitat destruction (D) Overexploitation
Answer: C. Habitat destruction (driven mostly by agriculture, logging, and urbanization) is the #1 driver of species extinction. The HIPPCO acronym lists drivers in approximate order of impact.
Drill flashcards
pollution-and-climate Tropospheric ozone (bad) Tap / Space to flip
pollution-and-climate Ground-level O₃; secondary pollutant from NOx + VOCs + sunlight. Lung irritant; component of photochemical smog.
pollution-and-climate Major greenhouse gases Tap / Space to flip
pollution-and-climate Water vapor (largest %), CO₂ (anthropogenic driver), CH₄ (~25× CO₂), N₂O (~300×), CFCs (1000s×).
pollution-and-climate Global Warming Potential (GWP) Tap / Space to flip
pollution-and-climate CO₂-equivalent warming over 100 yr. CO₂ = 1, CH₄ ≈ 25, N₂O ≈ 298, SF₆ ≈ 22,800.
pollution-and-climate CFCs · Montreal Protocol Tap / Space to flip
pollution-and-climate 1987 treaty phased out CFCs (refrigerants, aerosols). Successful — Antarctic ozone is recovering.
Unit 9 Greenhouse effect Tap / Space to flip
Unit 9 GHGs absorb outgoing infrared, warming the lower atmosphere. Natural & necessary; the enhanced effect is anthropogenic.
Unit 9 Climate change impacts Tap / Space to flip
Unit 9 Sea-level rise, melting ice, intensified storms, droughts, range shifts, ocean acidification, coral bleaching.
Unit 9 Ocean acidification Tap / Space to flip
Unit 9 CO₂ + H₂O → H₂CO₃ → H⁺ + HCO₃⁻. Lowers pH, dissolves calcium-carbonate shells (corals, mollusks, plankton).