Methane (CH₄) is a colourless, odourless gas and the second most important greenhouse gas driving climate change after carbon dioxide (CO2). It is far more potent at trapping heat – over 80 times more powerful than CO2 over a 20-year period – but it breaks down in the atmosphere much faster, lasting around 12 years compared to centuries for CO2.
Think of methane as a short, intense burst of warming. Carbon dioxide is like turning up the thermostat permanently. Methane is like throwing a log on the fire – it blazes fiercely but burns out relatively quickly. This makes methane both a problem and an opportunity: cutting methane emissions delivers faster climate benefits than almost anything else we can do.
🌿 Why Methane Matters So Much in Ireland
Ireland has a methane problem unlike almost any other country in Europe. Agriculture is the single largest source of national emissions, responsible for 37.8% of the total in 2023. Within agricultural emissions, methane accounts for over 72% – overwhelmingly from enteric fermentation (the digestive process in cattle and sheep) and manure management.
Ireland has the highest proportion of agricultural emissions relative to total national emissions of any EU member state. This means methane is not a marginal issue here – it is the defining feature of Ireland’s emissions profile. In 2023, methane contributed 28.9% of Ireland’s total greenhouse gas emissions when measured as CO2 equivalent, compared to an EU average well below that.
The national cattle herd stood at 7.25 million animals in 2023. While dairy cow numbers have grown for 13 consecutive years following the removal of EU milk quotas in 2015, the herd began to decline in 2024 with a 2.9% overall reduction. Agricultural methane emissions fell 2.9% in 2024 as a result, though a 10.6% increase in nitrogen fertiliser use partially offset those gains.
🌿 Where Does Methane Come From?
Globally, over 60% of methane emissions come from human activity. The three biggest sources are agriculture, the fossil fuel energy system, and waste. In Ireland, the picture is dominated by agriculture, but each source matters:
🌿 Agriculture (Enteric Fermentation and Manure)
Cattle and sheep produce methane as a natural byproduct of digestion – essentially, they belch it. This enteric fermentation is Ireland’s single largest source of methane. Manure management adds more, particularly when slurry is stored in anaerobic (oxygen-free) conditions. Together, these account for the vast majority of Ireland’s methane output.
🌿 Waste (Landfill)
When organic matter – food waste, paper, garden clippings – decomposes in landfill without oxygen, it produces methane. Ireland’s waste sector emissions are relatively small compared to agriculture, but landfill gas capture and diversion of organic waste through composting and anaerobic digestion can reduce this further.
🌿 Energy (Natural Gas Leaks)
Natural gas is mostly methane. Leaks during extraction, processing, and distribution contribute to emissions. Ireland imports most of its natural gas and has limited domestic production, so this source is smaller here than in fossil-fuel-producing countries, but it is not zero.
🌿 Peatlands
Damaged or drained peatlands can emit methane, particularly when water tables fluctuate. Ireland’s peatland restoration programmes – including Bord na Móna’s rehabilitation of 33,000 hectares of former harvesting bogs – aim to stabilise these emissions and return peatlands to their natural role as carbon stores.
🌿 How Methane Warming Is Measured
Because methane and CO2 behave differently in the atmosphere, scientists use a metric called Global Warming Potential (GWP) to compare them. The standard approach (GWP100) measures warming impact over 100 years: by this measure, one tonne of methane equals roughly 28 tonnes of CO2. Over a 20-year timeframe (GWP20), the figure jumps to over 80.
Ireland, like most countries, reports emissions using GWP100 in line with IPCC and UN reporting guidelines. This is what you see expressed as MtCO2eq in national emissions reports. However, some scientists argue that the 20-year measure better reflects the urgency of methane reductions, since cutting methane delivers faster cooling effects than any other greenhouse gas intervention.
There is also growing discussion about biogenic methane – methane from biological sources like cattle, as distinct from fossil methane from oil and gas. Because biogenic methane comes from carbon that was recently in the atmosphere (absorbed by grass, eaten by cattle, belched as methane), it cycles differently from fossil methane, which releases carbon that has been locked underground for millions of years. A newer metric called GWP* attempts to account for this distinction, though it is not yet used in official reporting.
🌿 What Is Ireland Doing to Reduce Methane?
The agriculture sector has a 25% emissions reduction target under Ireland’s carbon budgets. Key mitigation measures targeting methane include:
- 🌿 Reducing nitrogen fertiliser use – synthetic fertiliser dropped from 408,000 tonnes in 2018 to under 281,000 tonnes in 2023, with switching to protected urea further reducing associated nitrous oxide (though this mainly targets N2O rather than methane directly).
- 🌿 Low-emission slurry spreading – techniques like trailing shoe and dribble bar application reduce methane and ammonia released during spreading. Teagasc promotes these through its Signpost programme.
- 🌿 Herd management – the national cattle herd declined by 2.9% in 2024, with dairy cow numbers down 1.7%. Further reductions in beef cow numbers are projected.
- 🌿 Feed additives – research into compounds like 3-NOP (Bovaer) that inhibit methane production in ruminant stomachs is advancing. These could reduce enteric methane by up to 30% per animal.
- 🌿 Slurry amendments – Teagasc research is testing additives that significantly reduce methane emissions from stored slurry.
- 🌿 Improved breeding and genetics – the Irish Cattle Breeding Federation (ICBF) is working on selecting for animals that produce less methane per unit of output.
Ireland is also a signatory to the Global Methane Pledge, launched at COP26 in 2021, which commits participating countries to reduce methane emissions by at least 30% from 2020 levels by 2030.
🌿 Why Cutting Methane Matters Beyond Agriculture
Because methane is so potent but short-lived, reducing it is considered the single most effective near-term strategy for slowing global warming. Methane has been responsible for roughly 30% of global warming since the Industrial Revolution. The UN Environment Programme’s Global Methane Assessment found that cutting methane emissions by 45% by 2030 would avoid nearly 0.3°C of warming by the 2040s.
For Ireland, this has practical implications. Even as the country works on long-term decarbonisation through renewable energy, retrofitting, and electric vehicles, reducing agricultural methane delivers climate benefits within a decade rather than over generations. It also reduces ground-level ozone – a harmful air pollutant that damages crops and causes respiratory illness.
🌿 Frequently Asked Questions
🌿 Why is methane worse than CO2 for climate change?
Methane traps over 80 times more heat than CO2 per tonne over 20 years. However, it only lasts about 12 years in the atmosphere, while CO2 persists for centuries. This makes methane a more powerful short-term warming agent but a less persistent one. Both gases need to be reduced – methane for near-term impact and CO2 for long-term climate stability.
🌿 How much of Ireland’s emissions come from methane?
Methane contributed 28.9% of Ireland’s total greenhouse gas emissions in 2023 (expressed as CO2 equivalent). The vast majority comes from agriculture – specifically from cattle digestion (enteric fermentation) and manure management. Ireland has the highest agricultural share of national emissions of any EU member state.
🌿 Can we reduce methane from cattle without reducing herd size?
Partially. Feed additives, improved genetics, better slurry management, and low-emission spreading technologies can all reduce methane per animal. However, most projections for meeting Ireland’s 25% agricultural reduction target assume some reduction in overall cattle numbers alongside these technological measures. The combination of both approaches is more likely to succeed than either alone.
🌿 What is the Global Methane Pledge?
The Global Methane Pledge was launched at COP26 in 2021 by the EU and the United States. It commits 159 participating countries, including Ireland, to collectively reduce global methane emissions by at least 30% from 2020 levels by 2030. Achieving this could avoid over 0.2°C of warming by 2050. Ireland’s contribution primarily involves reducing agricultural methane through the measures in the Climate Action Plan.