When I was asked to chair the Climate Change Advisory Council, I was concerned that our first job would be to tell Irish farmers that they would have to get rid of their cattle. Happily, the scientific advice we received in early 2016 was that things were more complicated. The science suggested that farmers would have to make changes over time, but the decarbonised Ireland of 2050 could still have cattle grazing on our pastures.
However, as agriculture accounts for more than a third of our greenhouse gas emissions, there are some major changes needed to dramatically reduce its contribution to global warming.
Most farm emissions come in the form of two gases – methane, largely breathed out by cattle, and nitrous oxide, substantially originating from fertiliser use. Nitrous oxide remains in the atmosphere indefinitely, in the same way as carbon dioxide from fossil fuels. By contrast, methane breaks up and disappears quite rapidly. Thus any reduction in methane emissions will eventually result in less methane in the atmosphere, while reducing emissions of the other gases will only stop making things worse.
The really big rise in methane emissions from Irish farms occurred between 1960 and our EU membership in 1973, when cattle numbers rose by 50 per cent in anticipation of access to the EU’s Common Agricultural Policy. Methane emissions today are a further 20 per cent higher than in 1973.
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At present there are two main ways to lower such emissions: reduce herd numbers, or develop a feed additive that reduces methane output from cattle and sheep. While there is promising research on additives from seaweed, it’s early days yet, and this is unlikely to make a significant contribution by 2030. We also need to find the best way to persuade cattle to eat the enriched feed, like children reluctant to eat their greens.
Because there’s still more work to be done on feed additive research, we are likely to need some reduction in cattle numbers to reach our 2030 emissions targets. However, if science provides a workable solution over the coming decade then, by 2040, a 50 per cent reduction in methane emissions could be possible, while maintaining a substantial herd. As the gas breaks down, fewer emissions will lead to a fall in the volume of methane in the atmosphere. In this way, agriculture’s reduced methane emissions could help offset some of the damage done by remaining emissions from the rest of the economy.
If Irish people were to eat less meat, that may be better for our health, but it will do nothing to help us meet our climate objectives
Tackling nitrous oxide is more urgent, because it does long-term irreversible damage – it has a cumulative, permanent effect on climate, it pollutes our rivers and lakes, and it is bad for biodiversity. The best way to reduce nitrous oxide is to use less fertiliser. Fortunately, one way to achieve this is to switch from single-species rye grass pastures to grassland that incorporates a range of other plants such as clovers, which fix nitrogen in the soil and reduce the need for enrichment. Once a multi-species pasture is established, it can simultaneously reduce emissions and other pollution, as well as saving farmers on the cost of fertiliser – a true win-win. However, this system is unfamiliar to many farmers. A second difficulty is the loss of production while reseeding and establishing the new multi-species pasture. Therefore, more species-rich grassland will need to be introduced gradually.
Another potential win-win is for farmers is to plant more trees. More trees in hedgerows will help the environment, but replanting individual fields as woodland can potentially offer farmers an alternative source of good income, while sucking carbon dioxide from the atmosphere. However, the licensing system remains an obstacle course. Another issue is that switching fields to forests is a one-way bet – there is no going back to pasture. So farmers need to be absolutely certain that such a change in land use will prove permanently profitable. Some farmers suffered from past ill-judged programmes to diversify production.
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If Irish people were to eat less meat, that may be better for our health, but it will do nothing to help us meet our climate objectives. It would just mean more of what we produce will be exported, leaving emissions unchanged.
Irish agriculture can be part of the solution, can help slow global warming, while giving farmers a good income. The priority this decade must be to reduce emissions of nitrous oxide from fertiliser use, helping our climate and the quality of our waterways.
Farming practices have changed hugely over my lifetime. Irish agriculture, with the right supports, offering the right incentives, is up to adapting to greener methods of production.
