Professor Jennifer McElwain:

We are living in and experiencing a changing climate. Human activity has resulted in widespread and rapid changes in climate which are already impacting us all today. Climate changes arising from our emissions of heat trapping greenhouse gases are not simply a future problem; rather, they are already our current reality. We have warmed the global climate by over 1°C and all that warming has been attributed to our activities. Put bluntly, we as a global society are not responsible simply for a proportion of the warming; rather, we are responsible for all of the warming members can see on the chart in front of them.

The changes we have seen are without precedent in both the rate of change and the present state of many components of the climate system globally for centuries to millions of years. We have now definitively shifted the climate system away from a safe operating space that enabled us to develop from hunter-gatherers through to our modern society. Human-induced climate change is modifying climatic extremes globally, with robust evidence that it is increasing the frequency and intensity of heatwaves and extreme precipitation events. Some of those are illustrated on the map. These changes are having real consequences already for societies and nature across the globe.

One of the major scientific innovations of the past decade has been our ability to link individual events to human-caused climate change. We are undoubtedly priming the climate system. While extremes have always occurred, we have now shifted the odds of these events happening and their magnitude in important and consequential ways.

Over Ireland, annual average temperatures are now approximately 1°C higher than they were in the early 20th century, with 16 of the 20 warmest years occurring since 1990 and 2022 being the hottest year on record up until the finalisation of this report. It has since been usurped by 2023. This is not the last time that the warmest year on record nationally will fall. Overall, when aggregated, there has been an increase in heavy precipitation extremes over Ireland across a range of indicators. This has led to impacts already being felt, including, likely, the recent examples of flooding across the island last summer. These recent events highlight the vulnerability of individuals, communities, sectors and ecosystems to climate change and indicate an adaptation deficit, which is a subject my colleagues shall return to later in this presentation.

The future climate is in our collective hands. Every action matters. With every additional increment of warming, impacts for Ireland will increase substantially. Deep, rapid, immediate and sustained emission reductions are required to keep global warming in line with the key Paris Agreement temperature goals, which are illustrated on the charts. To stabilise the global climate requires global carbon dioxide emissions to reach at least net-zero, with emissions of other greenhouse gases, including methane, substantially reduced on a sustained basis. If we can reach net-zero global carbon dioxide emissions by mid-century, then components such as temperature and precipitation, which react within years to decades to changes in radiative forcing, would stabilise within the lifetime of many of today’s younger citizens. However, it is critical to recognise that sea level, which is considered the great integrator, will continue to rise and will take thousands of years to stabilise, even once net-zero emissions are reached.

Early and rapid global action on emission reductions would likely leave an Irish climate at the end of the century that would be still broadly recognisable in comparison to today, whereas delayed action would likely leave an Irish climate that would be increasingly unrecognisable as the century progresses.

Under early action scenarios, illustrated by the paler yellow top panel of future predictions, the temperature increases averaged across the island of Ireland relative to the recent past would probably warm by just under 1°C by mid-century before falling back slightly towards the end of the century. Under late action scenarios, illustrated by the bottom three panels in dark red, by the end of the century it is projected that the temperature increase in Ireland could be almost 3°C warmer than the recent past.

Intense precipitation extremes will become more frequent and extreme in most regions of Ireland across a range of extreme precipitation indices. Critically, how much more frequent and extreme depends upon the degree of warming. It will depend on whether we will be in the light yellow or dark red scenarios. Storm surges and extreme waves will pose an ever-increasing threat to Ireland as sea levels continue to rise. Again, this threat will increase the more the planet warms.