GS Paper I 2021 · Q7
10 marks · 150 words Geophysical phenomena & changing features X-Ray · Core #55Mention the global occurrence of volcanic eruptions in 2021 and their impact on regional environment.
Approach · directive: “mention”
What it asks · Name the main 2021 eruptions and their locations, and describe their environmental effects on the surrounding regions, separating local from global effects.
It asks 2 things — answer each
- Mention: the major volcanic eruptions of 2021 and where they occurred
- Explain: their impact on the regional environment, and why it stayed regional rather than global
Open with · Eruptions in 2021 spanned the Atlantic, the Caribbean, Central Africa, Iceland and the Pacific Ring of Fire, with sharp but mostly regional environmental effects.
Cover
- La Palma, Canary Islands (September–December): at least 1,600 buildings and 4 sq km of crops destroyed (Copernicus via NASA).
- La Soufrière, St Vincent (April): first explosive event since 1979; thousands evacuated; ash reached Barbados.
- Nyiragongo, DR Congo (May): lava destroyed over 3,500 houses and Goma's main water reservoir (UNICEF).
- Fagradalsfjall, Iceland, and Japan's Fukutoku-Okanoba pumice rafts; Semeru, Indonesia, where pyroclastic flows mixed with rain into lahars.
- Regional effects: buried farmland, fouled water, sulphur dioxide haze and acid rain, disrupted flights and shipping.
- Global effect: climate impact needs about 5 teragrams of SO2 in the stratosphere; La Soufrière gave 0.4–0.6 Tg in its first week.
Close with · Volcanoes cool the planet only when sulphur reaches the stratosphere; the 2021 eruptions changed land, water and air around them instead, so hazard mapping and early evacuation matter most.
Add value (verified)
- NASA, citing a mid-December 2021 Copernicus update, reports the La Palma eruption destroyed at least 1,600 buildings and about 12 sq km of land, including at least 4 sq km of crops.A Changed Landscape on La Palma — NASA Earth Observatory ↗“the eruption has destroyed at least 1,600 buildings. Lava has consumed at least 12 square kilometers (5 square miles) of land, including at least 4 square kilometers of crops.”
- La Soufrière's April 2021 eruption, its first explosive event since 1979, spread ash over Saint Vincent and Barbados and forced thousands to evacuate.Eruption at La Soufrière — NASA Earth Observatory (April 2021) ↗“Eruptions at La Soufrière volcano have propelled ash and gas high into the air over the Caribbean islands of Saint Vincent and Barbados. The eruption—the volcano’s first explosive event since 1979—prompted thousands of people to evacuate.”
- A volcano needs to put about 5 teragrams of sulphur dioxide into the stratosphere to affect climate; La Soufrière delivered about 0.4–0.6 teragrams in its first week.Tracking La Soufrière's Plume — NASA Earth Observatory (April 2021) ↗“a volcano needs to inject at least 5 teragrams of sulfur dioxide into the stratosphere to have measurable climate impacts”
- At Semeru (December 2021), pyroclastic flows mixed with heavy rain and turned into lahars that rushed into populated areas.A Deadly Day on Mount Semeru — NASA Earth Observatory (December 2021) ↗“the pyroclastic flows mixed with large amounts of rainwater and morphed into muddy lahars that rushed down the mountain into populated areas.”
- Nyiragongo's eruption on 22 May 2021 destroyed more than 3,500 houses, 7 schools and 4 health centres near Goma and left nearly 200,000 people without drinking water.Nyiragongo volcano eruption: the aftermath — UNICEF DRC (8 July 2021) ↗“More than 3,500 houses, 7 schools and 4 health centres were destroyed and nearly 200,000 people were left without access to drinking water.”
- Fagradalsfjall in Iceland erupted on 19 March 2021 after lying dormant for 800 years, on the Reykjanes peninsula.NASA Earth Observatory, Fagradalsfjall Continues to Erupt (2021) ↗“On March 19, 2021, the Fagradalsfjall volcano erupted after lying dormant for 800 years.”
- Floating pumice from Fukutoku-Okanoba (rafts seen on 17 August 2021) can clog the cooling systems and engines of ships.NASA Earth Observatory, Fukutoku-Okanoba Explodes (August 2021) ↗“In addition to scratching hulls and propellers, floating chunks of pumice can clog cooling systems and engines.”
Question: UPSC's CS (Main) 2021, GS Paper I — paper ↗. Approach: Minimalist IAS, checked 16 Oct 2026 (how we verify) — UPSC publishes no model answers. ·
Model answer· 218words · Minimalist IAS
Eruptions in 2021 spanned the Atlantic, the Caribbean, Central Africa, Iceland and the Pacific Ring of Fire, with sharp but mostly regional environmental effects.
Major eruptions of 2021
| Eruption (2021) | Regional impact |
|---|---|
| La Palma, Canary Islands (from Sept) | 1,600+ buildings, 4 sq km of crops lost |
| La Soufrière, St Vincent (April) | thousands evacuated; ash reached Barbados |
| Nyiragongo, DR Congo (May) | 3,500+ houses lost; Goma's water reservoir hit |
- Others: Fagradalsfjall, Iceland (from March), after about 800 years dormant; pumice rafts from Japan's Fukutoku-Okanoba (August); deadly Semeru, Indonesia (December).
Impact on the regional environment
- Land and farms: lava and ash bury fields and settlements; La Palma lost at least 4 sq km of crops.
- Water and health: in Goma, nearly 200,000 people lost access to drinking water.
- Air: sulphur dioxide brings haze and acid rain; ash disrupts flights and pumice clogs ship engines.
- Lahars: at Semeru, pyroclastic flows mixed with heavy rain into muddy lahars that buried villages downslope.
Why the effects stayed regional
- Stratospheric threshold: climate impact needs about 5 teragrams of sulphur dioxide in the stratosphere; La Soufrière gave only 0.4–0.6 in its first week, so no Pinatubo-type (1991) cooling followed.
Volcanoes cool the planet only when sulphur reaches the stratosphere; 2021's eruptions instead reshaped nearby land, water and air, so hazard mapping and timely evacuation matter most.
Prepared by Minimalist IAS to the answer standard of Shivam Singh (mentor, 7 years) · facts checked against official sources (how we verify) · updated 16 Oct 2026. UPSC publishes no model answers: compare your structure and coverage with this, then write your own.
