Ireland has become very good at talking about climate ambition. We have targets, plans, sectoral ceilings and a strong climate law. And yet, when you look closely at many of our most consequential decisions, it is hard to escape the sense that we are still behaving as if the underlying physics of climate change does not quite apply.
This physics is simple. Climate change is driven by cumulative emissions – the total amount of carbon dioxide we add to the atmosphere over time, and by the absolute level of methane emissions. Not emissions intensity, and not whether emissions are rising or falling in a particular year. What matters is the total stock of greenhouse gases in the atmosphere.
This basic fact is why Ireland’s climate law is built around carbon budgets: legally binding limits on the total cumulative emissions we can produce over defined periods. Carbon budgets are how the law of physics is operationalised in policy – they are not political slogans.
And yet, much of our planning still treats emissions as if they were a flow problem – something we can deal with later, or offset with future action – rather than a stock problem that tightens with every year of delay.
Recent emissions trends illustrate the risk of this thinking.
Since 2021, Ireland’s emissions have fallen by around 3.5 per cent per year. That is encouraging, and means we are very close to meeting our first carbon budget. But these budgets were deliberately backloaded to allow time for infrastructure and systems to change. Much deeper cuts are required from now on to remain compliant.
If Ireland were to begin cutting emissions sharply now, reductions of around 8 per cent would be required annually to stay within carbon budgets. That is difficult, but it is possible if we rapidly implement the decarbonisation measures we already know work, and if we stop adding new sources of emissions. But if we delay ramping up efforts by just a few years, the required annual decarbonisation rate quickly rises into double digits. Delay long enough, and the maths demands reductions that are simply impossible.
This is not an argument for despair or defeatism, but for urgency.
The frustrating thing is that despite the availability of solutions, projections of emissions based on planned policies indicates that the rate of decarbonisation will slow down significantly rather than speed up. Under existing policies, Ireland is on track to emit all of the greenhouse gases allowed under its carbon budgets to 2035 by the end of this decade. In other words, the emissions that are meant to be spread over the next 10 years would, on current trajectories, be exhausted in five.
This gap is not just caused by a failure to implement decarbonisation measures quickly enough. Again and again, policy decisions are being taken that permit new emissions sources as if carbon budgets were optional.
Take data centres. As the constraints on the electricity system have tightened, data centres are increasingly seeking to connect directly to the gas grid to power their operations on-site, encouraged by the Commission for the Regulation of Utilities’ new policy that explicitly disregards cumulative emissions and carbon budgets. Planning applications often justify this by pointing to plans to decarbonise the gas network. But emissions released during the next decade, when global temperature rise is likely to exceed 1.5 degrees, cannot be wished away by promises about the 2040s.
A similar logic appears in debates about airport expansion. Climate impacts are frequently waved aside through appeals to future technology, efficiency gains, or by counting emissions only from ground operations and ignoring the aircraft themselves, which account for the vast majority of emissions. The climate impact of international aviation sits outside national carbon budgets, but the cumulative emissions and warming are still the direct result of domestic policy choices.
These examples demonstrate choices to overlook sources of warming. Taking them seriously would require difficult decisions, including constraining the growth in carbon-intensive sectors. This trade-off is typically not acknowledged in climate policy planning, but needs to be confronted if the gap between our legally binding carbon budgets and policies is to be closed.
The Intergovernmental Panel on Climate Change has put it plainly: every bit of warming matters, every year matters, and every choice matters. Carbon budgets are simply the accounting system for that reality. If we plan as though they do not apply, we continue to add to the problem and make it harder and more costly for future governments, engineers and communities to deal with the consequences.