Which of the following statements are correct about the deposits of ‘methane hydrate? 1. Global warming might trigger the release of methane gas from these deposits. 2. Large deposits of ‘methane hydrate’ are found in Arctic Tundra and under the seafloor. 3. Methane in atmosphere oxidizes to carbon dioxide after decade or two. Select the correct answer using the code given below.

Updated 11 Apr 2026 · From UPSC Prelims GS Paper I 2019, Q71

Contents12

UPSC Prelims GS2019Environment

A1 and 2 only
B2 and 3 only
C1 and 3 only
D1, 2 and 3

Show answer

Answer: (D) 1, 2 and 3

The correct answer is (D) — All three statements are correct.

Statement 1: Global warming can melt permafrost and warm ocean floors, which could release the methane trapped in hydrate deposits — a dangerous feedback loop.

Statement 2: Methane hydrate deposits are found in two main locations — under Arctic permafrost and beneath the ocean floor along continental margins.

Statement 3: Methane in the atmosphere gets converted (oxidized) to CO2 and water within about 10-20 years by reacting with hydroxyl radicals.

Tip:

Methane hydrate = ice-like methane stored underground/underwater.
Warming releases it → more warming (vicious cycle).
But methane breaks down in ~10-20 years.

Why this was asked

Methane hydrates contain massive amounts of methane gas trapped in ice-like structures in permafrost and ocean floors, and their release could accelerate global warming dramatically.

Arctic ice melting and ocean warming from climate change create a dangerous feedback loop where warming releases more methane, which causes more warming.

The question tests understanding of both the physical locations of methane hydrates and the atmospheric chemistry of how methane converts to CO2.

Methane Hydrates

Environment methane hydrate deposits

Methane Hydrates: Formation, Locations & Climate Implications

Must know

Methane hydrates are ice-like crystals containing methane gas, stored in permafrost and ocean sediments

Found in Arctic tundra and under seafloor along continental margins

Global warming can release methane from these deposits, creating a dangerous feedback loop

Good to know

Atmospheric methane oxidizes to CO₂ within 10-20 years

Methane hydrates (also called clathrates) are crystalline structures where methane molecules are trapped inside cages of water ice. They form under specific conditions of high pressure and low temperature, making them nature's way of storing massive amounts of methane gas in solid form.

Major Methane Hydrate Deposits

Location Type	Specific Areas	Formation Conditions	Estimated Reserves
Arctic Permafrost	Alaska, Siberia, Northern Canada	Cold temperatures + geological pressure	Hundreds of Gt of carbon
Ocean Sediments	Continental margins, deep sea floors	High water pressure + cold temperatures	Thousands of Gt of carbon
Shallow Seas	Beaufort Sea, Sea of Okhotsk	Combined permafrost + marine conditions	Significant but less quantified

Climate Feedback Mechanism

%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
  s1["`**Global Temperature Rises**
Due to greenhouse gas emissions`"]
  s2["`**Permafrost Melts & Oceans Warm**
Changing pressure-temperature conditions`"]
  s3["`**Methane Hydrates Destabilize**
Ice-like structure breaks down`"]
  s4["`**Methane Gas Released**
CH₄ escapes to atmosphere`"]
  s5["`**Enhanced Greenhouse Effect**
Methane is 25x more potent than CO₂`"]
  s6["`**Further Temperature Rise**
Positive feedback loop continues`"]
  s1 --> s2
  s2 --> s3
  s3 --> s4
  s4 --> s5
  s5 --> s6

Atmospheric Methane Cycle

Methane lifetime: Atmospheric methane oxidizes within 10-20 years through reaction with hydroxyl radicals (OH)

Oxidation process: CH₄ + OH → CO₂ + H₂O (converts to carbon dioxide and water)

Climate impact: Short-lived but 25 times more potent than CO₂ as greenhouse gas

Global warming potential: Extremely high in short term, moderate in long term due to breakdown

Global Distribution

Methane hydrates concentrate in Arctic permafrost and continental margin sediments where pressure-temperature conditions favor formation

Source: USGS.gov — Where are gas hydrates found? | U.S. Geological Survey · www.usgs.gov

Exam traps

Trap: Confusing methane hydrates with natural gas - hydrates are solid ice-like structures, not free gas

Trap: Thinking methane stays in atmosphere permanently - it oxidizes to CO₂ in 10-20 years

Trap: Assuming only Arctic locations - ocean floor deposits are actually larger

Trap: Missing the feedback loop - warming releases more methane, causing more warming

Global Warming Feedback Loops

Environment Global warming trigger release

Climate Feedback Loops: How Warming Accelerates Itself

Must know

Positive feedback loops amplify global warming effects

Permafrost thawing releases stored methane and CO₂

Ice-albedo feedback - less ice means more heat absorption

Good to know

Water vapor feedback - warmer air holds more moisture

Climate feedback loops occur when an initial warming triggers processes that cause additional warming. Unlike negative feedbacks that stabilize systems, positive feedbacks create runaway effects that accelerate climate change beyond the original trigger.

Major Climate Feedback Mechanisms

Feedback Type	Initial Trigger	Process	Result	Time Scale
Methane Hydrate	Ocean/permafrost warming	Hydrates destabilize	CH₄ release → more warming	Decades
Permafrost Carbon	Temperature rise	Frozen soil thaws	CO₂/CH₄ release	Decades to centuries
Ice-Albedo	Ice melting	Dark surfaces exposed	More heat absorption	Years to decades
Water Vapor	Temperature increase	More evaporation	H₂O traps more heat	Days to years
Forest Fires	Drought + heat	Vegetation burns	CO₂ release + less CO₂ uptake	Years

Permafrost Feedback System

# Permafrost Thawing
## Carbon Release
- Methane from hydrates
- CO₂ from soil organic matter
- Both are greenhouse gases
## Physical Changes
- Ground subsidence
- Infrastructure damage
- Wetland formation
## Amplification Effects
- Faster warming
- More thawing
- Self-reinforcing cycle

Exam traps

Trap: Confusing positive and negative feedback - positive feedback makes warming worse

Trap: Thinking feedback is immediate - most operate on decade+ timescales

Trap: Missing tipping points - beyond certain thresholds, feedbacks become unstoppable

Trap: Forgetting multiple feedbacks can operate simultaneously, compounding effects

Atmospheric Methane Chemistry

Environment Methane atmosphere oxidizes carbon dioxide

Methane in Atmosphere: Chemistry, Lifetime & Climate Impact

Must know

Atmospheric methane oxidizes to CO₂ within 10-20 years

25 times more potent than CO₂ as greenhouse gas

Short atmospheric lifetime but extremely high warming potential

Good to know

Oxidation occurs via reaction with hydroxyl radicals (OH)

Methane (CH₄) is a powerful but short-lived greenhouse gas. Unlike CO₂ which persists for centuries, methane breaks down relatively quickly through atmospheric chemical reactions, but its warming effect during that time is intense.

Methane Oxidation Process

%%{init: {"flowchart": {"wrappingWidth": 460}}}%%
flowchart TD
  s1["`**Methane Enters Atmosphere**
CH₄ from various sources`"]
  s2["`**Encounters Hydroxyl Radicals**
OH radicals act as atmospheric cleanser`"]
  s3["`**Chemical Reaction Occurs**
CH₄ + OH → intermediate compounds`"]
  s4["`**Further Oxidation**
Multiple reaction steps`"]
  s5["`**Final Products Formed**
CO₂ + H₂O (carbon dioxide + water)`"]
  s6["`**Methane Removed**
Process completes in 10-20 years`"]
  s1 --> s2
  s2 --> s3
  s3 --> s4
  s4 --> s5
  s5 --> s6

Greenhouse Gas Comparison

Gas	Chemical Formula	Atmospheric Lifetime	Global Warming Potential (20-year)	Global Warming Potential (100-year)
Carbon Dioxide	CO₂	300-1000 years	1 (reference)	1 (reference)
Methane	CH₄	10-20 years	84	25
Nitrous Oxide	N₂O	120 years	264	298
Fluorocarbons	Various	1-50,000 years	Variable	100-23,000+

Climate Policy Implications

Short-term impact: Reducing methane emissions provides immediate climate benefits due to short lifetime

Long-term perspective: Even after oxidation, methane becomes CO₂, contributing to long-term warming

Mitigation priority: Methane reduction is low-hanging fruit for climate action

Sources to target: Agriculture (rice, livestock), landfills, oil & gas leaks, coal mining

Exam traps

Trap: Thinking methane stays in atmosphere forever - it breaks down in 10-20 years

Trap: Using wrong GWP values - 25x is the 100-year potential, 84x is 20-year potential

Trap: Forgetting oxidation products - methane becomes CO₂, not just disappearing

Trap: Confusing atmospheric lifetime with residence time - they measure different things

Vector Test SeriesTruly personalised. Every test aims at your weak spots.Adaptive UPSC Prelims tests · real PYQs · daily study planStart free →