GS Paper 3
Context: Scientists are experimenting with feed supplements that can reduce a potent greenhouse gas belched out by stock animals like cattle, goats and sheep.
Ruminants release methane, the second most abundant greenhouse gas after carbon dioxide (CO2), which is seen as the biggest concern as well as the best opportunity for tackling global warming.
Although the warming effect of methane is 30 times greater than CO2, it is shorter-lived and lasts in the atmosphere for about 12 years.
In 2021, over 100 countries signed the Global Methane Pledge, where signatories agreed to take voluntary steps to reduce global methane emissions by 30 per cent from 2020 levels by the end of the decade.
The science behind high methane release in ruminants:
- Unlike other animals, ruminants have specialized digestive systems comprised of stomachs that have four compartments instead of one.
- Plant material is initially taken to the rumen, the largest compartment in the stomach that is inhabited by microorganisms such as fungi, bacteria, protozoa and archaea.
- These microorganisms break down the otherwise indigestible cellulose-rich plants to release protein and energy for their host animal in exchange for nutrition and shelter.
- But during this process, which scientists call enteric fermentation, one particular microbe, the archaea, combines CO2 and hydrogen made by the cellulose-digesting microbes to create methane. This means the archaeal population and a diet rich in roughage dictate the amount of methane released by a ruminant.
- The feed supplement prepared by scientists targets the archaeal population while boosting the growth of bacteria that are good at digesting feed.
- The supplement is a concoction of ingredients such as Indian cherry and Indian elm leaves, garlic oil, mustard oil, cottonseed oil, sodium nitrate and magnesium sulphate.
- While tree leaves possess compounds like saponins and tannins that are known to reduce archaeal population and cut off hydrogen supply to them, sodium nitrate and magnesium sulphate stimulate the growth of beneficial bacteria.
Examples from around the world:
- In 2021, the EU approved a feed supplement, Bovaer, developed by the Dutch bioscience company Royal DSM, saying it consistently reduces methane emissions from dairy cows by 30-80 per cent.
- Bovaer is a fine granular powder containing 3-nitrooxypropanol, which inhibits an essential enzyme responsible for methane production.
- Some experts are placing their bets on seaweed, particularly Asparagopsis taxiformis, a red alga growing in tropical and subtropical waters.
Global Methane Initiative: (Not to be confused with Global Methane Pledge, of which India is not a part)
- The Global Methane Initiative (GMI) is an international public-private partnership focused on reducing barriers to the recovery and use of methane as a valuable energy source.
- In 2004, 14 countries launched the original initiative. As of 2015, 41 countries, including India and the European Commission,are part of the initiative.
(Why did methane emissions spike in 2020?)
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