Dr. Frank McGovern:

I thank Deputy Bruton for the question. Obviously, the EPA is aware of the ongoing discussions and debates that are happening around methane. It is a complex issue. Methane is a relatively short-lived gas and has an atmospheric lifetime of approximately 12 years. What matters for global warming is the amount of the gas that stays in the atmosphere because, by staying in the atmosphere, it traps more energy, causing the heating effects that are seen in Ireland and elsewhere around the world. Given that it is a short-lived gas, on first principles, one would say that if we stabilise emissions to the atmosphere, then the concentration would stabilise after a period of a number of decades. However, what does not stabilise is the climate impact of that concentration in the atmosphere, which takes time to work through the climate system. It is a bit like boiling a kettle or a large container of water in that it does not reach the boiling point until a certain time. Therefore, in order to address that latency effect, the science would suggest that in order to stabilise the warming contribution of methane, we would need to reduce emissions by about 3% per decade for at least three decades in order to stabilise its contribution to global warming. I hope that clarifies the point.