From UPSC perspective, the following things are important :
Prelims level : Carbon Equivalents
Mains level : GHG emission control
New Zealand has started the world’s first genetic programme to address the challenge of climate change by breeding sheep that emit lower amounts of methane.
Methane breeding value
- Emissions, or put less politely, farts and burps, from ruminants such as sheep and cows, are a major contributor to methane in the atmosphere.
- This has long been recognised as a problem, but addressing it has been difficult because no one really knows how much the average cow or sheep emits.
- Scientists have been working on ways to modify animals’ food so they emit a little less, including feeding them things like garlic that intervene in the microbiomes in their guts to reduce the formation of methane.
- This, however, works only in farms where the animals’ feed can be regulated, and not with free-ranging animals such as sheep in New Zealand.
Why is methane such a problem?
- Methane, which is produced by cattle and sheep, as also by decaying organic matter, fires, coal mines, and factories producing natural gas, is a major greenhouse gas.
- It is much more potent contributor to atmospheric warming than carbon dioxide, even though methane does break down more easily than carbon dioxide.
- A report by the World Meteorological Organisation last month pointed out those atmospheric concentrations of carbon dioxide and other greenhouse gases reached new records in 2018.
- The concentration of carbon dioxide in the atmosphere reached 407.8 parts per million in 2018, compared to 405.5 ppm the previous year. This was 147% of the pre-industrial level of 1750.
- And the concentration of methane was 259% of the 1750 level, while nitrous oxide was at 123% above.
- Each greenhouse gas (GHG) has a different global warming potential (GWP) and persists for a different length of time in the atmosphere.
- The three main greenhouse gases (along with water vapour) and their 100-year global warming potential (GWP) compared to carbon dioxide are:
1 x – carbon dioxide (CO2)
25 x – methane (CH4) – I.e. Releasing 1 kg of CH4into the atmosphere is about equivalent to releasing 25 kg of CO2
298 x – nitrous oxide (N2O)
- Water vapour is not considered to be a cause of man-made global warming because it does not persist in the atmosphere for more than a few days.
- There are other greenhouse gases which have far greater global warming potential (GWP) but are much less prevalent. These are sulphur hexafluoride (SF6), hydrofluorocarbons (HFCs), and perfluorocarbons (PFCs).
- There are a wide variety of uses for SF6, HFCs, and PFCs but they have been most commonly used as refrigerants and for fire suppression.
- Many of these compounds also have a depleting effect on ozone in the upper atmosphere.