--- title: "Global warming: causes, consequences, remedies" subject: "Engineering Chemistry" chapter: 3 key: "semester_2/engineering_chemistry:global-warming" source: https://www.bctengineer.com/q/semester_2/engineering_chemistry/global-warming site: BCT Engineering --- # Global warming: causes, consequences, remedies Engineering Chemistry · Chapter 3: Environmental Chemistry - Asked in: 2074 Bhadra, 2+3 marks; 2071 Bhadra, 1+2+2 marks (asked 2 times) - Video: [Understand Global Warming & Climate Change | Greenhouse Effect | Causes, Effects, and Solutions](https://www.youtube.com/watch?v=nWPlf9ZpHBI) — Toppscholars - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_2/engineering_chemistry/global-warming - Whole chapter: https://www.bctengineer.com/md/semester_2/engineering_chemistry/chapter-3 ## Question How is global warming caused due to air pollution? Write the consequences of global warming and its possible remedies. ## Short answer Global warming is caused by increased greenhouse gases (CO2, CH4, N2O, CFCs) from fossil fuel burning, agriculture, and industry trapping infrared radiation. Consequences: glacial melting and sea level rise, extreme weather, crop loss, biodiversity loss, disease spread. Remedies: renewable energy, afforestation, energy efficiency, international agreements. ## Answer #### How global warming is caused Short-wave solar radiation passes through the atmosphere and warms the earth. The earth re-emits this energy as long-wave infrared radiation. Greenhouse gases absorb part of this infrared and send it back towards the earth, so the lower atmosphere is warmer than it would otherwise be (greenhouse effect). Human activities add more of these gases, so the effect is enhanced. ```text Sun │ short-wave ▼ ─────────────── GHG layer (CO₂, CH₄ ...) ▲ │ absorbs and returns IR │ IR ▼ =============== Earth surface (warms) ``` | Gas | Main sources | |---|---| | CO₂ (about 60 % of the effect) | Burning of coal, oil, wood; deforestation; cement industry | | CH₄ | Paddy fields, cattle (rumination), landfills, natural gas leaks, wetlands | | N₂O | Nitrogenous fertilisers, burning of biomass, nitric acid industry | | CFCs | Refrigerators, air conditioners, aerosols, foam | | O₃ (troposphere) | Photochemical reactions of vehicle exhaust (NOx + hydrocarbons) | #### Consequences - Melting of glaciers and polar ice, and rise of sea level (flooding of coastal regions, island nations). In Nepal, Himalayan glaciers are retreating and glacial lake outburst floods are a threat. - Changed rainfall patterns: more floods, droughts, storms and heat waves. - Loss of crop yield, food and water shortage; shifting of climatic zones. - Extinction of species and loss of biodiversity; coral bleaching. - Spread of diseases such as malaria and dengue to new areas. #### Possible remedies - Reduce use of fossil fuels; use renewable energy (hydro, solar, wind), improve energy efficiency. - Afforestation and stopping deforestation (trees absorb CO₂). - Use public transport, electric vehicles and biogas. - Control methane from landfills and agriculture; reduce use of nitrogen fertiliser. - Stop using CFCs; follow international agreements: UNFCCC (1992), Kyoto Protocol (1997), Paris Agreement (2015). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. How do greenhouse gases cause warming? A. They absorb long-wave infrared emitted by the earth and send part of it back B. They block short-wave sunlight from reaching earth C. They absorb all visible light and cool the surface D. They reflect infrared into space Answer: A. Sunlight passes in as short-wave; earth's IR is absorbed and re-radiated back. (Key point: Greenhouse mechanism) 2. CO2 contributes about what share of the enhanced greenhouse effect? A. About 6% B. About 60% C. About 20% D. About 95% Answer: B. CO2 is the largest contributor, about 60%. (Key point: CO2 share) 3. Which is a consequence of global warming? A. Growth of polar ice B. Fall in sea level C. Melting glaciers, sea-level rise and glacial lake outburst floods D. Fewer droughts and floods everywhere Answer: C. Warming melts ice, raising sea level; in Nepal GLOFs are a threat. (Key point: Consequences) 4. Which remedy helps reduce global warming? A. More use of fossil fuels B. Deforestation for farming C. More CFC use D. Renewable energy, afforestation and following UNFCCC, Kyoto and Paris agreements Answer: D. Cutting fossil fuels and absorbing CO2 with trees reduces warming. 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