Q6.
Discuss how human activities increase the concentration of greenhouse gases in the atmosphere. What would you do as an individual to reduce the emission of greenhouse gas?
Answer
Human beings add greenhouse gases in two ways — by releasing carbon that was locked away, and by destroying the systems that used to absorb it.
| Human activity | Gas added | How it works |
|---|---|---|
| Burning coal, oil and gas for electricity, transport and industry | CO2 | Carbon buried over millions of years in the slow carbon cycle is returned to the air in seconds |
| Deforestation | CO2 | Removes a carbon sink, and burning or decay of the trees releases their stored carbon |
| Paddy fields, livestock, landfills | CH4 | Anaerobic decay produces methane, a far stronger greenhouse gas than CO2 |
| Heavy use of nitrogen fertilisers | Nitrogen oxides | Excess nitrogen in soil is converted by microbes into nitrogen oxides that escape to the air |
| Cement, steel and brick making | CO2 | Both the fuel burnt and the chemical reaction itself release CO2 |
Evidence from Fig. 13.14 (the Keeling curve):
CO2 in 1960 ≈ 315 ppm CO2 in 2025 ≈ 420 ppm
Increase = 420 – 315 = 105 ppm
Percentage rise = (105 ÷ 315) × 100 = 33% (the book rounds this to "about 35%")
Rate ≈ 105 ppm ÷ 65 years ≈ 1.6 ppm per year
CO2 in 1960 ≈ 315 ppm CO2 in 2025 ≈ 420 ppm
Increase = 420 – 315 = 105 ppm
Percentage rise = (105 ÷ 315) × 100 = 33% (the book rounds this to "about 35%")
Rate ≈ 105 ppm ÷ 65 years ≈ 1.6 ppm per year
Why an individual's actions still count: a single household's emissions are small, but the total is simply the sum of hundreds of millions of households. That is the reasoning behind Mission LiFE (Lifestyle for Environment), the India-led global initiative introduced at the UN Climate Change Conference in 2021, which "encourages people to adopt mindful, eco-friendly lifestyles".
Sample answer — what I would do as an individual:
- Save electricity: switch off fans and lights when leaving a room, use LED bulbs, set the air conditioner no lower than 24 °C. Every unit of electricity saved is CO2 not emitted at the power station.
- Change how I travel: walk or cycle for short distances, use a bus or the metro, and share a car ride for school. Transport fuel is burnt carbon.
- Reduce, reuse, recycle: the chapter names this directly. Manufacturing anything new costs energy; a repaired or reused article costs almost none.
- Cut food and water waste: wasted food means wasted fertiliser, wasted irrigation and wasted fuel for cooking and transport.
- Plant and protect trees: a growing tree removes CO2 from the air by photosynthesis and stores its carbon in wood. India "has planted billions of trees".
- Support renewable energy: solar water heating or a rooftop solar panel at home replaces fossil-fuel electricity directly.
Tip: when you answer this in an examination, do not just list actions — say why each one lowers emissions. "Use a bicycle" is a habit; "use a bicycle, because petrol is fossil carbon and burning it puts CO2 into the air that the slow carbon cycle took millions of years to remove" is science.