Greenhouse gas
Several gases present in the atmosphere have a greenhouse effect.
They trap radiation rising from the Earth’s surface, adding heat to the atmosphere in the process, much like a tunnel on a fruit farm.
The main greenhouse gas linked to human activity is carbon dioxide (CO2).
Those caused by agriculture are methane (CH4) from livestock and nitrous oxide (N2O) from soil fertilisation. Greenhouse gas is often abbreviated as GHG.
Global warming
Average surface temperatures around the world have increased by an estimated 0.8°C since 1880 – that’s global warming.
This in turn leads to a range of changes in weather patterns such as rainfall, wind, frost days, etc – that’s climate change. The 2015 Paris Agreement aims to keep global warming “well below 2°C”.
Each greenhouse gas is associated with a global warming potential (GWP), which is adjusted as scientific knowledge evolves. International agreements consider their effect over 100 years (GWP100).
New research suggests that short-life gases such as methane could be considered differently because they disappear from the atmosphere long before 100 years (see ifj.ie/methane).
Emissions
An emission occurs every time a greenhouse gas is released in the atmosphere – for example, when a cow belches methane or a tractor’s exhaust expels carbon dioxide.
As different gases have different global warming potentials, scientists mandated by the world’s governments under the Intergovernmental Panel on Climate Change have calculated conversion rates to measure all greenhouse gas emissions in carbon dioxide equivalent (CO2). EU legislation applicable in Ireland estimates that methane’s global warming potential is 25 times more potent than that of carbon dioxide. For nitrous oxide, the rate is 298.
Abatement
Abating emissions simply means reducing them. Research on abatement examines what industries can do to cut emissions, what results this would achieve and how much money it would cost or save. Last year, Teagasc published the second edition of its Marginal Abatement Cost Curve (MACC) for agriculture.
It showed that the most efficient measures on Irish farms would be to plant trees, change fertiliser type from CAN to protected urea and improve dairy genetics (see ifj.ie/teagasc).
Sequestration
Sequestration is a fancy word for storage. Plants and some soils store carbon after removing CO2 from the atmosphere.
Ongoing research attempts to measure this sequestration accurately so that it can be harnessed in efforts to combat global warming.
Emerging and expensive technologies also attempt to do this artificially through so-called carbon capture and storage (CCS).
Offset
If we can prove sequestration is occuring, then the corresponding removals can be offset against emissions.
The resulting net emissions would be lower and help agriculture achieve its targets.
For example, planting trees contributes to removing carbon dioxide from the atmosphere and these credits can offset some methane emissions from ruminants.
Under European rules agreed for the period 2020-2030, Ireland obtained the highest such flexibility in the EU, with 5.7% of our 30% target allowed to come from offsets.
Mitigation
Efforts to mitigate climate change combine emission cuts and sequestration to reduce the volume of greenhouse gases in the atmosphere and their effect on future weather.
Adaptation
We know a degree of climate change has already happened and will continue.
Adaptation is necessary to cope with changing weather patterns, especially in farming, and governments are preparing strategies ranging from flood prevention to drought relief.
Carbon footprint
The carbon footprint of a product is the amount of greenhouse gases emitted during its production.
This can be very difficult to establish as a full life cycle analysis is required to track all emissions.
For example, those from milk include gases emitted by feed, pastures, livestock, machinery, processing and distribution.
The carbon footprint of 1kg of Irish milk is 1.14kg CO2e and that of 1kg of Irish beef is 11.58kg CO2e, according to Bord Bia.
ETS, non-ETS and effort-sharing
In the EU, individual large-scale emitters of greenhouse gases such as power stations are in the Emissions Trading System (ETS), which means they can buy and sell emission quotas across Europe.
The rest of us, including farmers, small businesses and households are in the non-ETS or “effort-sharing” sector under EU law.
This includes emissions from transport, heating and agriculture, and targets set for 2020 and 2030 extend across those industries.
Read more
What farmers can do to tackle climate change
Incentives needed for climate-friendly spreading – Teagasc
Defining year ahead for farming and climate
How much carbon is in my milk?
Biogas training comes to Co Fermanagh
Biogas plans withdrawn
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