Professor Barry McMullin:

I will mention both of them. On the reference year for the start of differentiation, Mr. Price and I are on record in published literature. We had a paper reviewing the original Paris test that the climate council implemented in the first round in which we pulled out this specific question of the reference year. At that point, having reviewed the wider literature around these things, we said exactly what the Senator said about 2015. It is questionable whether it is defensible at all but it is certainly the latest date one might defend in an international context.

On the question of the confusion of years for the testing of Irish contributions versus the required global effort, that was not actually evident in the original letter the council sent back to the committee. We engaged with the council, and we acknowledge the openness of and the engagement by the council with us. It clarified exactly what the Senator said in correspondence we can make available if the committee wishes, taking the Irish contribution as of 2100 and comparing it with the available warming at the time of global peak warming.

I am not speaking on behalf of the council - the committee can refer to the council itself - but in communication with us it explained this. It acknowledged it was a change from what it had done in the first cycle of the carbon budgets. It argued this arose because of a change in its methodology from global warming potential star, GWP*, to this new simple climate model called finite amplitude impulse response, FaIR. These are technicalities but its argument was that its intention all along has been to compare Ireland's long-term contribution to warming versus the peak requirement. Unfortunately, the world is not going to wait for Ireland's long-term contribution. The tipping points the Senator mentioned are going to be triggered - some of them are potentially already being triggered - as the global temperature inches past 1.5°C above pre-industrial levels. The risk of those tipping points being triggered occurs at that point. The temperature contribution right now is absolutely critical.

The committee would have to, in a sense, refer to the council for a more nuanced motivation of its position on this.

Going back to the question from Senator Noonan, this is exactly the sort of issue that is best teased out through an open peer-review process. It would not be reasonable for yourselves, a committee of parliamentarians, to be trying to adjudicate on that sort of issue. We are only raising these issues to explain why we believe there are matters of concern that have not adequately been addressed as yet and that, therefore, if the budgets were to be adopted as they stand there is a reasonable doubt as to whether they would meet the legal requirements of the Act. We are not lawyers but it certainly seems that this would not be a good basis for going forward.