UPSC Civil Services Examination — Environment & Ecology (Prelims GS and Mains GS-III) · India · Union Public Service Commission
Original practice questions written to the published syllabus · not past papersUPSC Civil Services Examination — Environment & Ecology (Prelims GS and Mains GS-III) is a government recruitment exam run by Union Public Service Commission, for candidates in India. Prelims: two objective papers (GS Paper I and CSAT). Mains: nine descriptive papers. Interview.
Official site: upsc.gov.in.
We have not been able to confirm these details against the exam body's own specification, so fees, dates and pass marks are left out on purpose. Check the current format, eligibility, fees and dates on the official site.
Applied and current-affairs framing: what the IPCC reports said, the meaning of 1.5 °C and carbon budgets, methane and short-lived climate pollutants, black carbon, ocean acidification and coral bleaching, tipping points and cryosphere change relevant to the Himalaya and monsoon.
The physical basis of climate change as assessed by the IPCC: the greenhouse effect, radiative forcing, the global carbon cycle, feedbacks, climate sensitivity, and the evidence for observed change. It goes well beyond the 'climate change and livestock' unit of veterinary environmental hygiene.
Our 21 UPSC Civil Services Examination questions in this subject: 13 easy, 6 medium, 2 hard, across 10 units.
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
These 10 were written to UPSC Civil Services Examination and are not shown on any other exam's page.
Climate, as opposed to weather, is conventionally described using statistics over a period of
A. 30 years
WMO convention uses 30-year periods (climatological normals) to describe climate, long enough to average out year-to-year weather and most interannual variability such as ENSO.
Which group of human activities is the largest anthropogenic source category of methane in global budgets?
D. Agriculture and waste: ruminants, manure, rice paddies, landfills and wastewater
Agriculture and waste together make up the largest anthropogenic category, with fossil-fuel production (leaks and venting) second. Nitric and adipic acid plants emit N2O; combustion and cement are CO2 sources rather than major methane sources.
Black carbon (soot) differs from sulphate aerosol in its climate effect because black carbon
D. absorbs sunlight and warms, and darkens snow and ice where it settles
Black carbon absorbs solar radiation, warming the layer it is in, and reduces snow albedo when deposited, so its forcing is positive, unlike scattering sulphate. It can affect clouds, and like other tropospheric aerosols it is removed in days to weeks.
Why does melting of floating Arctic sea ice add essentially nothing to global sea level, unlike melting of the Greenland ice sheet?
D. Floating ice already displaces its own mass of seawater, while ice on land adds new water to the ocean
By Archimedes' principle floating ice displaces water equal to its own mass, so its melt barely changes sea level (a tiny effect from the fresh–salt density difference). Land ice adds mass to the ocean. Sea ice is not grounded, does not evaporate away and has declined in all months.
Arctic amplification refers to
B. the Arctic warming more than twice as fast as the global average
Arctic amplification is the enhanced warming of the Arctic, more than twice the global rate, driven largely by snow and sea-ice albedo feedback and lapse-rate effects. It is unrelated to ozone holes, sea ice has declined, and 'the sound of ice cracking' is not a scientific term.
According to AR6, what was the remaining carbon budget from the start of 2020 for a 50 per cent chance of limiting warming to 1.5 °C?
A. 500 GtCO₂
AR6: 500 GtCO2 for 50% (400 for 67%, 300 for 83%). 1350 is the 50% budget for 2 °C; 2390 is historical emissions 1850–2019.
Which change does AR6 describe as irreversible for centuries to millennia?
C. Global sea level rise from ocean warming and ice-sheet loss
AR6: changes in the ocean, ice sheets and global sea level are irreversible for centuries to millennia. Heatwaves, urban sulphate and individual monsoon onsets respond on time scales of days to years.
Permafrost thaw is considered a climate feedback mainly because it
A. releases carbon dioxide and methane from long-frozen organic matter
Permafrost soils hold roughly 1400–1600 PgC; thaw lets microbes decompose this organic matter, releasing CO2 and CH4 and amplifying warming. Exposure does not raise albedo, thaw has no link to sulphate removal, and net carbon release, not uptake, is expected.
The term 'ocean acidification' describes
B. a fall in seawater pH from CO₂ uptake, although seawater remains alkaline
Acidification is the direction of change: CO2 uptake lowers pH, but the open ocean stays above pH 7. Acid rain has only a local effect on seawater, and pH is falling, not rising.
Which IPCC Working Group assesses the physical science basis of climate change?
B. Working Group I
WGI covers the physical science basis; WGII impacts, adaptation and vulnerability; WGIII mitigation; the Task Force on National Greenhouse Gas Inventories produces inventory guidelines.
This plan follows where our questions actually fall, so the time goes where the marks are likely to be. It is our reading of the syllabus, not the exam body's weighting.
Read the manual chapters for these first and do every worked question you can find on them.
Aim for one sitting per unit, then mixed questions across them.
Learn the definitions, classifications and standard numbers; these units are more often recalled than worked.
Come back to these after a first pass, untimed, and read every explanation, including for the options you rejected.
Do these early in revision so they are fast on the day.
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