Climate Change: UPSC Previous Year Questions (Environment and Ecology)
3 previous year UPSC Prelims questions on Climate Change (Environment and Ecology). Choose an option to see the answer and explanation.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 1–3 of 3 questions
UPSC 2019Environment and Ecology · Climate Change
Q1. In the context of which of the following do some scientists suggest the use of cirrus cloud thinning technique and the injection of sulphate aerosol into the stratosphere?
Explanation
There is a renewed interest in two dominant methods of geoengineering such as stratospheric sulphate aerosol increase and cirrus cloud thinning aims to reduce global warming effects. Geoengineering, often known as climate intervention, is the deliberate and extensive modification of the Earth’s climatic system with the intention of reducing global warming. The stratosphere can be injected with sulphate aerosol particles to block some of the sun’s rays and possibly cool the planet. Sulphur droplets are good at scattering the sun’s light back out into space and it does not heat the stratosphere as much as other aerosols.
UPSC 2019Environment and Ecology · Climate Change
Q2. Consider the following statements: 1. Agricultural soils release nitrogen oxides into the environment. 2. Cattle release ammonia into the environment. 3. Poultry industry releases reactive nitrogen compounds into the environment. Which of the statements given above is/are correct?
Explanation
As per the Indian Nitrogen Assessment report, 2017, the share of agriculture in total GHG emissions has gradually declined from 28% in 1994 to 14% in 2016. Agricultural emissions in India are primarily from the livestock sector (54.6%) and the use of nitrogenous fertilizers (19%). Rice cultivation in anaerobic conditions accounts for a major portion of agricultural emissions (17.5%).
Statement 1 is correct: Agricultural soils release nitrogen oxides into the environment Fertilizers (especially nitrogen-based like urea) lead to the emission of nitrous oxide (N₂O), a greenhouse gas. Microbial processes such as nitrification and denitrification release NO, NO, and NO.
Statement 2 is correct: Cattle release ammonia into the environment Cattle excrete urea in urine, which breaks down into ammonia (NH₃) through microbial action. Livestock farming is a major contributor to ammonia emissions.
Statement 3 is correct: Poultry industry releases reactive nitrogen compounds into the environment Poultry litter (manure, bedding material, and feed waste) contains nitrogen compounds that can convert into ammonia, nitrates, and nitrites. This contributes to air and water pollution.
UPSC 2019Environment and Ecology · Climate Change
Q3. In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements: 1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions. 2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions. 3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses. 4. H-CNG makes the fuel less expensive than CNG. Which of the statements given above is/are correct?
Explanation
Hydrogen-enriched CNG (H-CNG) is a blended gas. It is produced by mixing hydrogen with CNG. HCNG reduces emissions of CO up to 70% and engines can be calibrated to release lower amounts of NO. enables up to 5 % savings in fuel. It can be the first step towards the future Hydrogen economy. It gives better performance due to higher Octane rating of H2.
Statement 1 is incorrect: HCNG doesn’t eliminate but reduces emissions of CO up to 70%.
Statement 2 is correct: It can be used in place of gasoline, diesel fuel and propane (C3H8) / LPG and its combustion produces fewer undesirable gases.
Statement 3 is correct: The blending of hydrogen with CNG provides a blended gas termed as HCNG. Also, the ideal Hydrogen concentration is close to 20 %. It can prove to be the ideal fuel for heavy-duty vehicles and applications with high loads.
Statement 4 is incorrect: The current cost of Hydrogen is more than the cost of Natural Gas. So, HCNG’s cost is more than CNG.
Exam tip:
When S2 says "Reduces", then, isn’t S1’s "Elimination of CO" an extreme phrase, hence S1 is more probable to be false, Also, what do you think is more practical and logical: Elimination or Reducing? Clearly Second one hence S1 false and S2 true giving option B as correct.
Answer key for these questions
Q
UPSC year
Correct answer
1
2019
(d) Reducing the global warming
2
2019
(d) 1, 2 and 3
3
2019
(b) 2 and 3 only
Frequently asked questions
How many previous year UPSC questions are there on Climate Change?
This page covers 3 previous year UPSC Prelims GS Paper-I questions on Climate Change (Environment and Ecology), asked from 2008 to 2025. Each has the correct answer and an explanation.
How should I use previous year UPSC questions for Prelims?
Attempt each question first, then open the answer and read the explanation for every option. Repeat by chapter, and track which statements UPSC reuses across years. Previous year questions show the exam pattern and difficulty level.
Which years are covered for Climate Change?
Questions on Climate Change (Environment and Ecology) are available for 14 years, from 2008 to 2025. Use the Year filter to practise a single paper.
