Dr. David Styles:

I thank the Chair for the opportunity to present here today. I am a lecturer in environmental engineering at the University of Limerick. We did some work on the land use sector for the carbon budget committee. With respect to Deputy Bruton's previous question, I would like to clarify that we did a little bit of work that looked at land use and it was very clear that the 51% target for land use by 2030 is exceedingly difficult to achieve, to say the least. One of the reasons for that is that land use comprises both the big emission source from organic soils, which are drains for agricultural production, and peat extraction. There is approximately 10 million tonnes of CO₂from those annually. We also have a sink in the land use sector, which is unique. We have the removal of carbon dioxide and forestry growth. That offsets 5.5 million to 6 million tonnes of CO₂if one accounts for the wood going into wood products, which continue to store carbon.

One of the problems is that because of very low planting rates recently, that sink is projected to decline dramatically over the next decade. Almost a doubling of emissions in the land use sector is projected by 2030, while we are aiming for a 51% reduction. That is a massive challenge in the land use sector that illustrates the degree of activity change we might need.

Dr. Hanrahan alluded to the fact that we can rewet organic soils and that is an important thing we are going to have to do to reduce emissions. That can be done in a more timely fashion and once we rewet those soils, we can curtail emissions. However, the forestry side takes a while to ramp up so we have limited planting rates and a build-up of the carbon offset that we achieve for any given area that is planted with forest. Those two things together mean it will take some time to build up the offset we need in the land sector to offset emissions from other parts of the land sector, agriculture and other parts of the economy in time. The 2030 targets, for that reason, are extremely difficult and almost impossible, one could argue, for the land sector.

There has been a lot of focus on the longer term offsets and strategy that might be needed for the land sector. When we think about activity change and, for example, planting areas with forest, it is not just the 2030 targets but also the 2050-and-beyond climate neutrality target that we need to think about. Because of the long lead-in time, although some of those activities might not contribute as much to the carbon budget as we might hope, they will certainly contribute to future carbon budgets in 2040, 2050 and beyond.

The activities linked with this mean there is a big land demand for some of these things. Up to 1 million ha could be required, long term, for rewetting and forest planting to achieve significant offsets. That obviously begins to compete with agriculture. These are political decisions. As Dr. Hanrahan and Dr. Daly said, this is not something for us to decide. However, we note there will be real trade-offs although there may also be new income streams from this diversification. We know we need to use bio-based materials in other sectors to decarbonise those sectors for energy generation, including renewable building materials, etc. There are opportunities here to build new sectors and bio-based economy activity derived from this change in land use. That was a reply to Deputy Bruton's previous question on the scale of the challenge in respect of land use change.

Deputy Whitmore asked about modelling and peer review. The forestry side of the model that we use, the general overview for a back-casting approach of livestock intensification, GOBLIN, model, was reviewed in previous work that was undertaken and we simply took that part of the model that was published in the Journal of Environmental Management. We took that part of the forestry model and incorporated it into our bigger land use model. The bigger land use model, GOBLIN, is currently in the final stages of peer review in Geoscientific Model Development, an international journal. We have got quite positive feedback and we hope the model will be fully peer reviewed within the next few months. That is a specific response to Deputy Whitmore's question.