Professor Peter Stott:

Yes and I will try to be brief. I thank the Deputy for his questions.

I have been involved in the attribution science area for a long time. The nub is trying to understand the world in which we live today and the counterfactual world in which we could be living if we had not collectively changed the climate. In comparing the two scenarios we can work out how things have changed in ways which are attributable to human induced emissions. We have shown that we can do this reliably because we have the climate models and understanding to simulate quite accurately on a large scale the current climate and how it has changed over time. For example, the work I did on the European heatwave is robust and the calculations I made demonstrated that the risk of such a heatwave had more than doubled. Subsequent work indicates that the work I did was quite robust.

That brings me to the question of a cost-benefit analysis. The science is starting to try to assess the probability of such events and using attribution science to do so. That is to what the question alludes. It is probably fair to say it is still difficult to be very precise about the cost-benefit trade-off.

One needs to understand quite clearly what the costs are, including the avoided costs, and the role adaptation has played. We are adapting. If we look back to the 2003 heatwave, lessons were learned and, thankfully, some of the impacts of it have not been felt since, because the societal systems are better adapted to supporting vulnerable people through heatwaves.

It is not a straightforward exercise. The science can, nevertheless, inform this, especially when it is thought of in a risk context, and can highlight some of the risks and provide storylines of what might happen, what is happening and what we might have avoided. In that storyline context, that can be quite helpful.

On the question on the meteorological service, I refer to the Met Office in the UK. We are now working in the Hadley Centre for Climate Prediction and Research, which was set up many years ago by our Prime Minister at the time, Mrs. Thatcher. We have had a long remit to look at climate projections. Later this year we will be releasing a new set of climate projections for the UK. That will provide a lot of information in this risk-based context and will provide probabilistic information, because we cannot provide a single figure as to what the temperature or heatwaves will be in 50 years' time. What we can provide is a probability, and provide that contextual information for people to understand that and to engage in planning. However one does this exercise, it is important to do this in the probabilistic sense, which folds in one's scientific understanding. There are plenty of quite sophisticated uses where that information can be taken and applied it in their particular context. As to 1.5° report, what I learned just as I came in, is that the committee will hear evidence from the co-chair of working group one, and the co-chair of working group three, who are currently at the plenary meeting in Korea, agreeing that report. This is happening this week. It would be most appropriate to defer that answer to them, if the committee agrees. For sure, as one goes to higher levels of warming, there will be more overall net consequences of climate change, which is true relative to 1.5° Celsius. The co-chairs will be able to provide the committee with much more information on that, which will be in light of a report that will have been approved and published.

As to costs, there are very significant costs associated with extreme weather such as heatwaves, floods, droughts and windstorms. They increase with climate change, but I do not have a precise number for Ireland. It is a good question to ask, however, as to what sort of estimates might be available here.