Dr. Hannah Daly:

I would like to perhaps offer some clarifying points on the Paris test and on the top-down assessment to the Senator. The question on the Paris test is a very good one as to how we assess the compliance of different carbon budgets against the Paris Agreement.

To be clear, first, the modelling was led by the requirement for emissions to reduce by 51% by 2030. That was the bottom-up scenario that was given and is fundamentally where the carbon budgets that were recommended came from. The council then assessed the implications of those budgets against the global carbon budget on how much the potential global carbon budget was for different temperature limits. The Paris test is one such way of doing that. The carbon budget fellows Andrew Smith and Paul Price did literature reviews. It was very clear that the assessment of what is the fair share against the Paris Agreement goals is very normative. It requires an assessment of what the temperature goal is. Are we going for 1.5° or well below 2°? What is the likelihood that we want to achieve that goal? This is a very different global carbon budget if one has a 66% chance of meeting a 1.5° target versus a 50% chance of well below 2°.

Another issue Senator Higgins alluded to was the fairness of this. Do we divide that global carbon budget on a per capitabasis? Do we, for example, take into account historic responsibility and capacity? Then also, what is the starting point? Even if one has a starting point at 2015 versus 2020, the fair share for Ireland is very different.

The carbon budgets that were assessed are the cumulative emissions over the next ten years. We also have to take into account a number of different factors when measuring their assessment towards the global carbon budget. What is the speed of decarbonisation post-2030 and what is the scale of negative emissions that can be achieved once we get to net zero, which would potentially offset the positive emissions in the next ten years?

What is also very important is the measurement of the relative impact of methane emissions. We are almost unique as a developed country in having a high share of methane emissions and the metric used to assess the ongoing warming impact of methane creates a very different answer. I wanted to clarify that there is not just one solution but there are many different effects and the council assessed that the Paris test was the mechanism that required the fewest normative judgements.