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. 2. Methane in atmosphere oxidizes to carbon dioxide after a decade or two. Select the correct answer using the code given below:

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. 2. Methane in atmosphere oxidizes to carbon dioxide after a decade or two. Select the correct answer using the code given below: Correct Answer 1, 2 and 3

The correct answer is option 4, i.e 1, 2 and 3.

• Large but poorly known amounts of methane are trapped in the sediments beneath the sea floor frozen into a form of water ice is called methane hydrate.
• Methane hydrate is an "ice" that only occurs naturally in subsurface deposits where temperature and pressure conditions are favourable for its formation.
• Four earth environments have the temperature and pressure conditions suitable for the formation and stability of methane hydrate. These are:
  1. sediment and sedimentary rock units below Arctic permafrost;
  2. sedimentary deposits along continental margins;
  3. deep-water sediments of inland lakes and seas; and,
  4. under Antarctic ice. Hence, statement 2 is correct.
• At low temperatures the methane hydrates on the sea floor are stable, but if the water and the sea floor become warmer, then the hydrates can break down. The microorganisms present there then oxidises the resulting methane gas to form the greenhouse gas carbon dioxide (CO₂).
• Thus, owing to melting of ice, global warming might trigger the release of methane gas from these deposits hence having a significant impact in climate change. Hence, statement 1 is correct.
• Methane is relatively short-lived in the atmosphere; a molecule of methane is oxidized to water and carbon dioxide within a decade or so, mainly by reaction with another trace gases. Hence, statement 3 is correct.
• Thus, there is concerted effort to reduce methane emissions in order to reduce the greenhouse effect.