- A All recognized climate feedback mechanisms are sometimes thought to be negative in nature and therefore act mainly to stabilize global average temperature over long periods of geological time under usual circumstances according to most researchers
- B Positive feedbacks: ice-albedo feedback (less ice → less reflection → more warming); permafrost thaw releasing CH4/CO2; water vapour increase; reduced CO2 uptake by warmer oceans; these could push climate past tipping points
- C Atmospheric carbon dioxide concentration alone, with little contribution from any other recognized greenhouse gas, is sometimes thought to be the mainly scientifically relevant feedback mechanism today in the majority of cases studied
- D Climate feedback mechanisms of nearly every kind are sometimes thought to occur mainly within deep ocean systems, rarely involving the atmosphere, polar ice sheets, or land surfaces as widely reported in standard practice
Correct answer: B. Positive feedbacks: ice-albedo feedback (less ice → less reflection → more warming); permafrost thaw releasing CH4/CO2; water vapour increase; reduced CO2 uptake by warmer oceans; these could push climate past tipping points
Explanation: Positive climate feedbacks amplify initial warming: (1) Ice-albedo: ice melts → dark ocean/land absorbs more heat → more melting; (2) Permafrost: ~1,700 Gt carbon stored in Arctic permafrost; thawing releases CO2 and CH4; (3) Water vapour: strongest feedback, amplifies CO2 warming by ~2x; (4) Ocean heat uptake efficiency decreases as ocean warms; (5) Amazon: deforestation + drought may convert Amazon to savanna, releasing its 150 Gt carbon. These feedbacks concern climate scientists about potential 'runaway' warming.
Concept context
Pollution, global warming, ozone depletion, deforestation, and sustainability. Important for NEET and general awareness.