Ms Sadhbh O'Neill:

I would like to come in on Deputy O'Sullivan's question. It might be helpful to make a distinction between sequestration and offsetting. When we discuss sequestration, we are talking about the ability of land, trees, soils, hedgerows and plants to absorb carbon from the atmosphere. As Professor Matthews highlighted, that is difficult to measure because it changes over time and is affected by weather patterns, climate change and drought. If trees are chopped down, they are clearly not sequestering carbon any more. Given that land use is subject to so much change over time, it is difficult to say that when trees, for example, sequester a tonne of carbon, it is permanently offsetting a tonne of fossil carbon that is released into the atmosphere. For that reason, quite a number of scientists and environmental non-governmental organisations, NGOs, recommend we do not use land-based sequestration to offset any fossil carbon.

In addition to that, we have a problem in Ireland because, as Professor Matthews highlighted, we are releasing more carbon than we are sequestering. Some of the anxieties the Deputy is describing he hears from farmers is around a misunderstanding of that reality. It is not, in fact, the case that they are sitting on carbon treasure. The reality is that we are releasing millions of tonnes of carbon from drained soils, bogs and also from a certain amount of deforestation that takes place.

The issue is that sequestration policies are beneficial for biodiversity and soil health but are very limited in what they can do for climate mitigation in the short term. Given the length of time that carbon dioxide stays in the atmosphere, it is vital that we take measures to drastically cut emissions form fossil carbon and, at the same time, protect the carbon sinks that we already have in our soils and forests.

Hedgerows and carbon stocks are only roughly estimated. It is very difficult to calculate them with any degree of accuracy. We do not have the tools yet to do that. Of course, as I say, one would need to be measuring it on an ongoing basis because it is subject to change all the time. What information is there is already included in the Environmental Protection agency, EPA, reports. These values, it claims, are subject to a high degree of uncertainty. The EPA also highlights that total hedgerow length has decreased over the past few years in Ireland and there is a widely reported increase in hedgerow cutting, suggesting that there is a net loss of carbon from hedgerows.

In addition to that, the EPA has reminded us time and again that we can only take credit for any changes in land use. The existing store of carbon is not what farmers will be able to use to establish any credits, if you like, against their emissions. They would have to increase the sequestration, afforestation and so on for that to be counted in any sense. It is important that we distinguish between sequestration and the measures we take to draw down more carbon by protecting soils, planting more hedgerows and engaging in more forestry.

When it comes to offsetting, we need to be clear that land-based offsets do not reduce emissions. The problem is establishing permanence and additionality. There is a lack of measurement tools to capture the changes over time. The offsetting programmes we have seen emerging around the country through the voluntary carbon markets often use inappropriate metrics based on carbon intensity and not absolute emissions.

I will also highlight the fact that if there is a mechanism to establish carbon trading schemes within farms, there would need to be corresponding adjustments to the national inventory to reflect the fact that the credits are now being sold to somebody else, perhaps a company. They would have to be added back to the national inventory, if that makes sense. This is the subject of current discussions under the UN convention on Article 6 of the Paris Agreement. It is highly complicated and will not be a quick fix for Ireland's agricultural challenges.