--- title: "Climate change gases and mitigation interventions" subject: "Technology, Environment and Society" chapter: 6 key: "semester_7/technology_environment_and_society:cc-gases-interventions" source: https://www.bctengineer.com/q/semester_7/technology_environment_and_society/cc-gases-interventions site: BCT Engineering --- # Climate change gases and mitigation interventions Technology, Environment and Society · Chapter 6: Climate Change - Asked in: 2074 Chaitra, 8 marks - Video: [Climate Change and Global Warming: Explained in Simple Words for Beginners](https://www.youtube.com/watch?v=G9t__9Tmwv4) — Science ABC - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/technology_environment_and_society/cc-gases-interventions - Whole chapter: https://www.bctengineer.com/md/semester_7/technology_environment_and_society/chapter-6 ## Question What is climate change? State and explain gases which cause climate change. Discuss all the possible interventions to mitigate climate change. ## Short answer Climate change is long-term change in average weather from human-emitted greenhouse gases. Main gases are CO2 (most important), methane, nitrous oxide, halocarbons, water vapour, ozone and black carbon. Interventions include renewable energy, efficiency, electric transport, forest conservation/REDD+, sustainable agriculture, cleaner industry and waste management, carbon pricing and awareness. ## Answer **Climate change** is a significant long-term change in the average weather (temperature, rainfall, wind, seasons) of a place or of the Earth as a whole. The present change is mainly due to human emission of **greenhouse gases**, which trap extra heat and cause global warming. #### Gases causing climate change Greenhouse gases are transparent to incoming sunlight but absorb outgoing infrared heat from the Earth and send part of it back, warming the lower atmosphere. ```text Sun (short-wave radiation) | v ======== atmosphere with GHGs ======== ^ some heat escapes | GHGs absorb and | v re-emit heat back ----------- Earth's surface ------------ (absorbs light, emits long-wave heat) ``` | Gas | Main sources | GWP (100 yr, IPCC AR5) | Lifetime | |---|---|---|---| | Carbon dioxide (CO₂) | Burning coal, oil, gas; deforestation; cement | 1 | Centuries | | Methane (CH₄) | Paddy fields, livestock, landfills, gas leaks | 28 | ~12 years | | Nitrous oxide (N₂O) | Nitrogen fertilisers, manure, burning | 265 | ~120 years | | CFCs / HCFCs / HFCs | Refrigerators, ACs, aerosols, foams | Thousands | Decades–centuries | | Sulphur hexafluoride (SF₆) | Switchgear insulation | ~23,500 | ~3,200 years | | Water vapour (H₂O) | Evaporation (feedback, not directly emitted) | – | Days | | Tropospheric ozone (O₃) | Formed from NOₓ and VOCs from vehicles | – | Weeks | - **Carbon dioxide (CO₂)** is the most important gas because of its huge quantity. Its concentration has risen from about 280 ppm before the Industrial Revolution to over 420 ppm today, mainly from fossil fuels and loss of forests. - **Methane (CH₄)** comes from anaerobic decomposition in rice fields, livestock digestion, landfills and leaks from gas wells. It traps about 28 times more heat than CO₂ per kg over 100 years. - **Nitrous oxide (N₂O)** is released from chemical fertilisers, animal waste and biomass burning. It is long-lived and also damages the ozone layer. - **Halocarbons (CFCs, HCFCs, HFCs)** are man-made gases from refrigeration and air conditioning. CFCs also destroy stratospheric ozone; they are controlled by the Montreal Protocol (1987) and HFCs by its Kigali Amendment (2016). - **Water vapour** is the most abundant natural greenhouse gas. It is not emitted directly by people, but warmer air holds more of it, so it amplifies warming (positive feedback). - **Ozone and black carbon** (soot from brick kilns, diesel and firewood) are short-lived climate pollutants. Black carbon deposited on snow makes it darker, so glaciers melt faster. #### Possible interventions to mitigate climate change **1. Energy sector (largest source of CO₂)** - Shift from coal, oil and gas to renewable energy: hydropower, solar, wind, geothermal, biogas. - Improve efficiency in power plants, buildings, appliances and industry. **2. Transport** - Electric vehicles and electric mass transit (e.g. Nepal's electric buses and reduced customs duty on EVs). - Better urban planning, cycling lanes, footpaths. **3. Forestry and land use** - Stop deforestation, afforestation and reforestation; community forestry (Nepal's forest cover has risen to about 45%). - REDD+ payments for keeping forests standing. **4. Agriculture** - Organic farming and balanced fertiliser use to cut N₂O. - Improved rice cultivation (alternate wetting and drying) to cut methane; biogas from dung. **5. Industry and waste** - Cleaner brick kilns, low-clinker cement, recycling. - Landfill gas capture, composting, waste-to-energy. **6. Policy and economic tools** - Carbon tax, emission trading, removal of fossil-fuel subsidies, green building codes. - Climate finance and technology transfer to developing countries. **7. International cooperation** - UNFCCC, Kyoto Protocol, Paris Agreement and NDCs; Montreal Protocol and Kigali Amendment for halocarbons. **8. Research and technology** - Carbon capture and storage, green hydrogen, better batteries. **9. Awareness and behaviour** - Saving energy, using public transport, reducing food waste, sustainable consumption. Mitigation should go together with **adaptation**, especially in vulnerable countries like Nepal. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. The present climate change is mainly due to: A. Natural volcanic cycles only B. Human emissions of greenhouse gases that trap extra heat C. Changes in the Moon's orbit D. Increase in ozone in the stratosphere Answer: B. Human greenhouse gas emissions trap extra heat, causing global warming and climate change. (Key point: Climate change definition) 2. What are the main sources of N2O and one more effect of it? A. Rice paddies; it is short-lived B. Refrigerators; it has GWP of 1 C. Fertilisers, animal waste and biomass burning; it is long-lived and also damages the ozone layer D. Landfills; it is lasting only days Answer: C. N2O comes from fertilisers, manure and burning, has a lifetime of about 120 years and harms the ozone layer. (Key point: Nitrous oxide) 3. Which intervention cuts methane from rice cultivation? A. Continuous flooding B. Alternate wetting and drying C. More chemical fertilisers D. Burning straw Answer: B. Alternate wetting and drying reduces anaerobic conditions that produce methane; organic farming/balanced fertiliser cut N2O. (Key point: Agriculture interventions) 4. Why is the energy sector the first target for mitigation? A. It is the largest source of CO2, so shifting to renewables and improving efficiency cuts emissions most B. It has no emissions C. It is the smallest sector D. Because it only produces methane Answer: A. The answer calls the energy sector the largest source of CO2; renewables and efficiency are key interventions. (Key point: Energy sector intervention) ## Related in Technology, Environment and Society - [Climate change: cause, impact and mitigation](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Acc-cause-impact-mitigation) — Technology, Environment and Society, chapter 6 - [Climate change gases, impact and mitigation](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Acc-gases-impact-mitigation) — Technology, Environment and Society, chapter 6 - [Climate change gases, mitigation and international efforts](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Acc-gases-international-efforts) — Technology, Environment and Society, chapter 6 - [Short note: International efforts to mitigate climate change](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Ainternational-efforts-note) — Technology, Environment and Society, chapter 6 - [Climate change gases and symptoms in Nepal](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Acc-gases-symptoms-nepal) — Technology, Environment and Society, chapter 6 - [Climate change threat, impact and mitigation](https://www.bctengineer.com/question.md?key=semester_7%2Ftechnology_environment_and_society%3Acc-threat-impact-mitigation) — Technology, Environment and Society, chapter 3 ## Related in other subjects - [Climate change and renewable mitigation](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Aclimate-change-renewables-mitigation) — Energy Environment and Society, chapter 4 - [Biogas routes and climate change](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Abiogas-routes-climate-change) — Energy Environment and Society, chapter 3 - [APA and MLA: newspaper article (Clinton on Climate Change)](https://www.bctengineer.com/question.md?key=semester_5%2Fcommunication_english%3Aapa-mla-harris-clinton-climate) — Communication English, chapter 4