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. Methane contributes 62.5% of all Irish agricultural emissions according to Teagasc.
Ireland has the highest proportion of agricultural emissions relative to total national emissions of any EU member state. 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 grew 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 in cattle numbers. Agricultural methane emissions fell 2.9% in 2024 as a result, though a 10.6% increase in nitrogen fertiliser use partially offset those gains. In the first nine months of 2025, enteric fermentation emissions fell further (-180.9 kt CO2eq) driven by continued herd reductions, with dairy cow numbers down 2% though milk output per cow increased 5.7%.
🌿 Where Does Methane Come From?
Globally, over 60% of methane emissions come from human activity. In Ireland, agriculture dominates, but other sources contribute:
🌿 Agriculture – Enteric Fermentation and Manure
Cattle and sheep produce methane as a natural byproduct of digestion. Microbes called archaea in the rumen (the animal’s first stomach) convert hydrogen and CO2 produced during digestion into methane, which the animal mainly belches out. A single dairy cow can produce 100-150 kg of methane per year. With over 7 million cattle in Ireland, the cumulative impact is enormous. Manure management adds more methane, particularly when slurry is stored in anaerobic (oxygen-free) conditions over winter.
🌿 Waste – Landfill
When organic matter decomposes in landfill without oxygen, it produces methane. Ireland’s waste sector emissions are smaller than 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, so this source is smaller here than in fossil-fuel-producing countries.
🌿 Peatlands
Damaged or drained peatlands can emit methane when water tables fluctuate. Ireland’s peatland restoration programmes – including Bord na Móna’s rehabilitation of over 20,000 hectares of former harvesting bogs – aim to stabilise these emissions.
🌿 How Methane Warming Is Measured
Scientists use Global Warming Potential (GWP) to compare methane with CO2. The standard approach (GWP100) measures warming over 100 years: one tonne of methane equals roughly 28 tonnes of CO2. Over 20 years (GWP20), the figure jumps to over 80. Ireland reports emissions using GWP100 in line with IPCC guidelines, expressed as MtCO2eq.
There is growing discussion about biogenic methane – methane from biological sources like cattle, where carbon cycles through grass, animal, atmosphere and back to grass, as distinct from fossil methane from oil and gas which releases carbon locked underground for millions of years. A newer metric called GWP* attempts to account for this, 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. Teagasc – the state agency for agricultural research – is leading a major research effort through projects including METH-ABATE and MAGS, focused specifically on methane reduction in Ireland’s pasture-based systems. This matters because 90% of Irish milk is produced in seasonal spring-calving systems where cows graze outdoors for much of the year – making methane reduction harder than in housed systems common elsewhere in Europe.
🌿 Feed Additives
The most advanced solution is Bovaer (3-NOP), the only EU-approved feed additive for methane reduction. It blocks the enzyme that archaea use to produce methane in the rumen. In housed systems, Bovaer reduces methane by around 30% in dairy cattle and up to 45% in beef cattle with no negative effects on milk yield or animal performance. Teagasc trials at Johnstown Castle confirmed a 26% reduction for indoor Irish winter-milk dairy cows.
The challenge is Ireland’s grazing systems. When Teagasc tested Bovaer with cattle at pasture using twice-daily feeding, the reduction was only 6-7% because the effect is transient – it wears off between feeds. Research is now focused on slow-release formats, including rumen boluses and encapsulated pellets, that could maintain the effect throughout a full day of grazing.
Other additives being tested by Teagasc include linseed oil (18% reduction), rapeseed oil (9%), and seaweed extract (7%) in indoor trials. A calcium peroxide supplement developed by a Galway company (Glasport Bio) achieved a 28% reduction in beef cattle when formulated into pellets – a significant advantage for delivery. The MAGS project (€1.4 million), led by University of Galway with Teagasc, AFBI, and ICBF, is evaluating novel slow-release additives combined with genomic breeding for lower-methane animals.
🌿 Genetics and Breeding
The Irish Cattle Breeding Federation (ICBF) has published the world’s first genetic methane evaluations for beef cattle, using data from 1,600 animals collected through the DAFM-funded GREENBREED project. Research shows some beef cattle naturally emit up to 30% less methane for the same level of performance. Selecting for these traits through breeding offers a permanent, cumulative reduction over generations – though it takes time to filter through the national herd.
🌿 Grassland Management
Teagasc research has found that incorporating clover (white or red) into grazing swards can reduce methane output per animal. Multi-species swards – mixtures of grasses, clovers, and herbs – are being evaluated both for methane reduction and for reducing dependence on nitrogen fertiliser, addressing two emission sources simultaneously.
🌿 Fertiliser and Slurry Management
Synthetic nitrogen fertiliser use dropped from 408,000 tonnes in 2018 to under 281,000 tonnes in 2023 – a significant reduction. Switching from calcium ammonium nitrate to protected urea reduces nitrous oxide emissions (the other major agricultural greenhouse gas). Low-emission slurry spreading techniques like trailing shoe and dribble bar – promoted through Teagasc’s Signpost programme – reduce both methane and ammonia released during application. Slurry additives that reduce methane emissions from stored slurry are also under active research.
🌿 Herd Management
The national cattle herd declined 2.9% in 2024, with dairy cow numbers down 1.7% and non-dairy cattle down 3.2%. Further reductions in beef cow numbers are projected. Reducing the age at which cattle are finished for slaughter also cuts total lifetime methane emissions per animal.
Ireland is a signatory to the Global Methane Pledge, launched at COP26 in 2021, committing 159 countries to reduce global 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 the single most effective near-term strategy for slowing global warming. Methane has driven roughly 30% of global warming since the Industrial Revolution. The UN’s Global Methane Assessment found that a 45% cut 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. It also reduces ground-level ozone – a harmful air pollutant that damages crops and causes respiratory illness – since methane is a precursor to ozone formation.
🌿 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. Both gases need to be reduced – methane for near-term impact and CO2 for long-term stability.
🌿 How much of Ireland’s emissions come from methane?
Methane contributed 28.9% of Ireland’s total greenhouse gas emissions in 2023 (as CO2 equivalent). The vast majority comes from cattle digestion and manure management. Methane alone accounts for 62.5% of Irish agricultural emissions according to Teagasc. 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 like Bovaer can reduce methane by up to 30% per housed animal, genetics can select for lower-emitting cattle, and better grassland management helps. But in Ireland’s pasture-based systems, additive effectiveness drops significantly (to 6-7% at pasture with current delivery methods). Most projections for meeting the 25% agricultural reduction target assume a combination of technology and some reduction in cattle numbers.
🌿 What is Ireland doing differently from other countries on methane?
Ireland’s unique challenge is that 90% of dairy production is pasture-based, meaning solutions designed for indoor systems elsewhere do not transfer directly. Teagasc is leading globally relevant research into slow-release feed additive formats, grazing-compatible delivery mechanisms, and the world’s first genetic methane evaluations for beef cattle through the ICBF. The €1.4 million MAGS project combining feed additives with microbiome-assisted genomic breeding is one of the most ambitious integrated methane research programmes in Europe.