Professor Myles Allen:

I thank the committee for bringing me in. I prepared a short briefing note on technical matters, which I hope was made available to members. I am happy to share it with anybody who does not have a copy of it.

I am here to brief on, specifically, the matter of measurement of methane and its impact on global temperature. On the broader policy questions the Deputy raised, given my citizenship and accent, I do not think I am qualified to speak to them.

However, what I can do as a climate physicist sitting outside of this discussion is tell him a little about how I feel there is a lot of unnecessary animosity in this. He mentioned the 3% per decade. If you are reducing methane emissions from whatever source by 3% per decade - which as Dr. Mitloehner mentioned, is entirely achievable and, in fact, you can probably do much better than that – those methane emissions then are not contributing to any additional global warming. I choose my words carefully here because they will have, in building up the herd back in the day, contributed to global warming. It is important to acknowledge that in any discussion about sectoral responsibilities. When the Deputy is talking about agriculture’s responsibilities, by all means he can talk about what Irish agriculture may have contributed to global warming in the past.

However, all I advocate – this is just speaking as a scientist – is can we please measure the impact of everything we discuss on global temperature? It is a source of some embarrassment that you have a method of characterising environmental impact of greenhouse gases that does not actually reflect the impact on global temperature. The Deputy is looking me like, “So what have you been doing for the past 30 years?” He has a point. He should be looking at me like that. To be fair, we know how to do it right. There are relatively simple ways of calculating the impact of emissions on global temperature and they were all well documented in the recent IPCC report. It is universally agreed among the scientists who work in this sector that that is what we should document. Unfortunately, in our formal reporting requirements that we place on farmers and countries reporting to United Nations Framework Convention on Climate Change, UNFCCC, we are still using this old and, frankly, not fit for purpose metric of CO2 equivalent emissions, which does not reflect the impact of methane emissions on global temperature.

If there is one thing I ask members to take away from this meeting, it is to let Ireland be a policy pioneer in reporting the warming impact of policy on global temperatures. In the briefing note I provided, I included a graph to illustrate the difference it makes. The blue line on that graph represents the actual impact. One can calculate the impact of Ireland's methane emissions on global temperature under a scenario in which, hypothetically, there is a reduction of 51% by 2030 and net zero in 2050. I am not suggesting that is a policy scenario; it is just to illustrate the way these gases behave. The dotted line represents the CO2 equivalent metric, which is the sort of standard carbon footprint that we report and everybody uses, in the context of what those methane emissions are doing. Members will notice that it underestimates the warming caused by Ireland's methane emissions to date. It is not saying not to worry about methane at all but, as soon as methane emissions start to decline, the actual impact on global temperatures follows them down, whereas the carbon footprint calculation suggests that their warming impact carries on up. It even gets the sign wrong when one moves into a situation of declining methane emissions. We are using a tool that does not reflect the impact of emissions on global temperature. I am not suggesting that Ireland abandon that tool. It is embedded in international policy, and I am sure Ireland will carry on using it because everybody else uses it too. What I am suggesting, however, is that reporting requirements be added in. That could even be at farm level. Mr. Hourigan could work out with a pocket calculator his impact on global temperatures. Those reporting requirements would assist in targeting policies to maximise the reduction in global temperature. That is what we are trying to do. We are trying to stop global warming. That is what we should focus policy on.

My response to the Deputy's many questions is to document and report the impact of policies and emissions on global temperatures. That would be a very easy innovation to do and it is something the Climate Change Advisory Council can already do. If that was introduced into the conversation, it would do a great deal to defuse the tension between the farming community and the Government on this issue.