Dr. Frank O'Mara:

I will provide some more facts about hedgerows in light of the Deputy's interest in that matter in particular. Ireland has 690,000 km of hedgerows. Per hectare, we have approximately 150 m of hedgerows. The figure is probably a little higher on grassland farms, given that tillage farms tend to have bigger fields and fewer hedges. The average width of those hedges is approximately 2.7 m. As the Deputy rightly alluded, just having the hedgerow is acting as a store, but the additional sequestration is what is important. We get that by either planting additional hedges or allowing the existing hedgerow cohort to add more biomass. Current research is focused on quantifying the potential for sequestration through hedgerow management or further planting. That work is in progress, but it is an active area for us. While hedgerows might not have as much sequestration potential as soils, they are nevertheless an important sequestration route that we want to quantify better.

I will quickly answer another question before addressing biogenic methane. The Deputy asked about the EU study that we referred to in our opening statement. It was published by the Joint Research Centre of the European Commission in 2010 or 2011. It only went as far as the farm gate, that is, the emissions inside the farm gate, but that accounts for most of the emissions in a dairy or beef product. The life cycle analysis of dairy products in particular suggest that approximately 90% of the overall emissions occur inside the farm gate, with processing and transport representing small amounts. Of course, factoring in the food waste that happens after food leaves the supermarket shelf is a whole other scenario. As the committee knows, quite a bit of food gets wasted.

We were not trying to give the impression that biogenic methane was irrelevant to global warming. The reason biogenic methane is being spoken about so much now has to do with the Paris Agreement, where we shifted from talking about controlling greenhouse gas emissions to controlling global warming and we put a target on the amount of warming.

A molecule of methane is a molecule of methane, wherever it comes from. The issue with methane that comes from enteric fermentation in animals is that it has come from plants taking carbon dioxide out of the atmosphere in the process of photosynthesis. The animal eats the grass or other plant and respires most of it back out as carbon dioxide, which is the carbon cycle. Carbon moves from the atmosphere into plants, into animals and back out, effectively, but with ruminants some of the carbon dioxide taken from the atmosphere is put back out as methane. Methane stays in the atmosphere for about 12 years or a half-life and reverts into carbon dioxide. Again, it is part of the carbon cycle and the carbon that is in methane was originally carbon dioxide from the atmosphere. That is different from fossil-derived methane whereby the carbon dioxide therein was taken out of the atmosphere a million years ago or some such. That is why biogenic methane is singled out. We were not trying to say that it does not have an impact while it is there. In terms of its warming impact, it is part of a fairly short cycle of 12 to 15 years so in theory, if we keep its concentration in the atmosphere stable, there is no additional warming. On the other hand, if we emit carbon dioxide from burning fuels like diesel or petrol, that will stay in the atmosphere for thousands of years and will contribute to warming over a very long period. That is why scientists are trying to figure out how we can account for methane and biogenic methane in particular in our climate targets now, when our focus is on warming rather than just on the emission of greenhouse gases. I hope that answers the question. It is a complex topic and one on which we could spent a lot of time but in the time available, that is the best answer I can give.