25 August 2021
The IPCC report released a few weeks ago stated that strong, rapid and sustained
reductions in methane emissions are needed to limit further warming.
Even though methane is
one of the most powerful greenhouse gases, it can also be a bit misunderstood. Most
of us know that it has something to do with cow fartsand that is a more powerful warming force than
carbon dioxide in the atmosphere. But that still leaves a lot more to uncover.
To extract out what’s
important to know, we talked to some people in the know to give you the
low-down on methane.
let’s start with
the basics. What is methane?
has a global warming potential 28 times that of carbon dioxide emissions over a
100-year period – it ‘lives-fast’. It is a ‘die-young’ greenhouse gas because
it stays in the atmosphere about 12 years, after which it breaks down into
carbon dioxide and water.
This is “a very
potent, powerful, greenhouse gas,” according to climate scientist and research
fellow Paul Price. But he also said, “it can be confusing to say it’s a
If we continue
emitting the gas, then the warming effect will continue as well. This is
despite methane’s shorter atmospheric lifespan than carbon dioxide’s, which Mr.
Price says is ‘essentially forever.’
Mr. Price uses a
helpfulanalogy of a tap:if the tap is on, and we are emitting the gas, there
will be a continued warming effect. But if the flow (i.e. annual emissions) decreases,
then the warming will decrease.
So, the short-lived
nature of the gas is only beneficial to mitigate the effects of climate change
if we actually reduce emissions.
Alright, I get
methane’s impact in the atmosphere, but where does it come from?
Methane comes primarily from three sources – fossil
fuels, waste, and agriculture.
It leaks during oil
and gas extraction as well as throughout the production of coal. Globally, those
fossil-fuel related activities account for 35 per cent of methane emissions.
Landfills and waste management account for a further 20 per cent of emissions and
agriculture accounts for the remaining 40 per cent of the methane pie.
(Livestock is the largest source of methane within agriculture, but more on
There are anthropogenic
(read: human-caused) sources of methane and there are natural sources of
methane. The difference between the two is related to agency.
As Mr. Price stressed,
“If we can make choices that can reduce it and mitigate it, then that is an
anthropogenic greenhouse forcing.”
Many of these sources
would leak methane regardless of human activity. For example, coal in the
ground is natural source of methane. But when humans intervene and extract that
coal at an accelerated rate, it becomes anthropogenic.
I’m guessing the
methane source that is most relevant in Ireland is agriculture – is that right?
accounts for just over one third of Ireland’s total greenhouse gas emissions
and over two thirds of its methane emissions.
In agriculture, methane
comes mainly from cows. In Ireland, 58 per cent of the total methane emissions
comes from the rumen of cattle – which is basically them just existing. A
further 10 per cent comes from the storage of manure and slurry.
and farmer Emma Carroll recognises that methane is “one of the biggest problems
in Ireland, in terms of greenhouse gas emissions.”
She stressed that
farmers face both the pressure to produce food and the pressure to reduce
“We can do better,”
she told The Green News.
What are some ways the
agriculture sector could reduce their methane emissions?
There is a certain
amount of methane emissions that are locked in as long as cattle are raised in
Ireland. But we do have some agency in this – both in terms of herd size, and
in how livestock waste is managed.
“There are other
technologies that we could possibly use that would be really helpful. Both from
a farming perspective and also from a greenhouse gas perspective,” Mrs. Carroll
technology to look at is anaerobic digestion. This process (which could probably have its
own explainer) uses the absence of oxygen to break down animal waste. The
result is methane-rich biogas which produces heat, and can be used to generate
But anaerobic digestion
can “create a positive feedback effect to create more emissions and more
nitrogen use,” according to Mr. Price.
He says that this
process makes some “bad assumptions”, and noted the concerns that he and others
have. For example, creating a higher demand for animal waste could lead to an
increased demand for bigger herds, which leads to more emissions. There is a
similar unintended consequence with nitrogen use – more demand of the output
can also lead to more demand on the input.
Most of the methane
emissions comes from the cow’s digestions, so diet modifications are another
way methane could be reduced. Mrs. Carroll says, people suggest feeding the cows seaweed, but she says “it’s not really that
There are other things
to consider, like how much seaweed would need to be grown, and if it would affect
marine ecosystems. Recent reports also indicate that the amount of methane
reductions the feed would bring would also be relatively low.
(Want to read up more
on that? Wired had a
piece on it earlier this year).
Then, there are the
anthropogenic sources of methane. When milk quotas were abolished, it led to an increase in Ireland’s livestock
herd and dairy cow
numbers increased by one third from 2010-2018.
“We have control over how
many cows there are and what kind of cows they are,” said Mr. Price. He stressed
that dairy cows emit more methane than other cows.
Considering the type
and amount of livestock, he says we can take responsibility for what we do
control and can work to emit less.
I’ve heard some
talk about ‘biogenic methane.’ Is that methane any different than regular
Yes, and no.
Biogenic methane is
methane that comes from living creatures – that’s where the bio comes in. it comes
from biological processes rather than other processes like leaking methane gas
from coal. It breaks down slightly differently than other kinds of methane. But
it doesn’t make that much of a difference.
“When you’re talking
about biogenic, it’s being used as if that means natural, but it isn’t natural,”
according to Mr. Price. He stressed that methane has the same warming effects,
regardless of the source.
“Methane with a fossil carbon atom in it has the same effects until
it breaks down as one with a biogenic carbon atom in it,” he told The Green
Mrs. Carroll echoed
this point. “Methane is methane in the atmosphere. The atmosphere doesn’t
Does it seem likely
that we will reduce methane emissions in Ireland?
It largely depends on
how the agriculture sector responds.
With the EPA calling for greater cuts to meet
targets and scientists still working to
emphasise the importance of methane, it seems that agriculture has yet to step up and reduce their
As a farmer, Mrs.
Carroll acknowledges the challenges that face this sector. Farms are Ireland’s most dangerous work places. Speaking from her experience, she says that
“farmers are just out there doing their bloody best. It’s hard, it’s really,
With demands to
increase production and balance their books, it can be challenging for farms to
fund ways to reduce emissions. So it’s a difficult system. But she believes
it’s possible for farmers to get on board, especially if it secures their
“We can make these
changes,” Mrs. Carroll urged. “We need leadership to step up. We need
communication to improve, but I’m hopeful and I’m optimistic that we can do it.”
By Sam Starkey