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Monday, December 09, 2019

Explained: Why New Zealand is trying to breed sheep that will emit less methane

Emissions, or put less politely, farts and burps, from ruminants such as sheep and cows, are a major contributor to methane in the atmosphere.

By: Explained Desk | New Delhi | Updated: December 2, 2019 8:12:08 am
Why New Zealand is trying to breed sheep that will emit less methane Emissions, or put less politely, farts and burps, from ruminants such as sheep and cows, are a major contributor to methane in the atmosphere. (Representational Image)

New Zealand has started what it says is the world’s first genetic programme to address the challenge of climate change by breeding sheep that emit lower amounts of methane.

Gene-modifying techniques are recognised as a potential way to reduce greenhouse gas emissions from livestock; however, regulatory controls in many countries of the world stand in the way of experimenting widely with this idea.

What is it with methane and sheep?

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 some studies notwithstanding, no one really knows how much the average cow or sheep emits, and what to do about it except to try to process manure in ways that minimize the leakage of the gas.

Scientists have been working on ways to tweak the 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 freeranging animals such as sheep in New Zealand.

There have been campaigns to get human populations to eat less red meat, or to produce ‘vegetarian’ meat in laboratories, but these are small steps yet in what is a very big problem.

But 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, and a much more potent contributor to atmospheric warming than carbon dioxide. (Even though methane does break down more easily than carbon dioxide.)

Research has been reporting a sharp spike in the concentration of methane in the atmosphere in recent years.

A report by the World Meteorological Organisation last month pointed out that 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.

And does New Zealand have many sheep?

Yes, a very large number — some estimates have claimed there are 20 sheep in the country for every human being.

That is an exaggerated figure — as of mid 2015, New Zealand had 4.6 million people, and about 29.5 million sheep, according to official statistics.

This works out to be about six sheep per person, which, though still a lot, is significantly lower than the peak numbers of 1982, when the country had 70.3 million sheep, or about 22 sheep per person.

The New Zealand government’s statistics website also says that people in the country are also outnumbered by cattle — there were 6.4 million dairy and 3.6 million beef cattle in mid 2015.

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