Supercomputers provide New Climate Projections for Ireland

A timely new report by climate scientists at the Irish Centre for High-End Computing (ICHEC) and funded by the Environmental Protection Agency (EPA), Met Eireann and the Marine  Institute addresses a research gap in previous regional climate projections for Ireland which showed large uncertainty for certain climate projections, such as precipitation. The Updated High-Resolution Climate Projections for Ireland increase confidence in climate projections for Ireland which, if realised, will impact Ireland’s economy, society and environment in dramatic ways.

Dr Paul Nolan, Climate Scientist, ICHEC lead author of the report said: “It is imperative that planners and policymakers are adequately informed about future climate change so that appropriate mitigation and adaptation measures can be implemented. This research will inform national policy and further our understanding of the impacts of climate change in Ireland at a local scale.”

Key Findings: What the Future Holds for Ireland’s Climate

The updated projections offer a clearer picture of the climate changes Ireland can expect. Below are some of the key findings of the report:

• Temperature: Near-surface temperatures are projected to rise by 0.5–0.7°C (2021–2050) under a low-emission scenario (SSP1-2.6), and by 2.4–3.0°C (2071–2100) under a high-emission scenario (SSP5-8.5), with the largest increases observed in eastern Ireland.
• Extreme Weather: Heatwaves are expected to become more frequent, while frost and ice days will decrease. The rainfall climate is projected to become more variable across extremes; both dry spells and extreme rainfall events will intensify.
• Precipitation: The rainfall climate will become more variable across the seasons. Winter and autumn months are projected to become wetter, while summer rainfall is expected to decrease by up to 8% by the end of the century.
• Snowfall: Snowfall is expected to decline sharply, with reductions of up to 84% by 2100 under the highest emissions scenario.
• Growing Seasons: The length of the growing season is projected to increase, benefiting agriculture with warmer soil temperatures and improved conditions for crop production.
• Energy: Wind energy potential is projected to decrease, particularly in summer, while photovoltaic power is expected to decline across all seasons.
• Heating Demand: With warmer winters, heating demand in Ireland is expected to decrease over the coming decades.

What’s new in the latest report?

The research improves on previous research by simulating the future climate at a higher spatial resolution (4 km) using the most up-to-date regional climate models to downscale an ensemble of CMIP6 global datasets under the new SSP-RCP emission scenarios.

An increased ensemble size of projections was completed which allows for a more accurate quantification of climate change uncertainty. For example, there is disagreement in the ensembles for projections of annual rainfall, so this projection is assigned lower confidence. Conversely, there is high agreement in the ensemble of temperature projections, and as such we assign high confidence to this projection. Furthermore, the current report provides projections for additional climate variables and derived metrics that are critically important to biodiversity and to key Irish sectors, including agriculture, health, energy and transport.

The SSP–RCP scenario-based national projections are supplemented with global warming threshold (GWT) scenario projections. These alternative scenarios have garnered substantial interest since the 2015 Paris Agreement (a United Nations treaty in which 195 nations pledged to tackle climate change), which aims to limit global warming to “well below” 2°C by the end of the century, and “pursue efforts” to keep warming within the safer limit of 1.5°C (UN, 2015). For example, the projections under the “1.5°C GWT scenario” show projections over Ireland in a world that is 1.5°C warmer than the period 1850–1900 (Figure 5). Note that temperature projections over Ireland are always less than the corresponding GWT.

Running such a large ensemble of high-resolution RCMs is a first for Ireland. This was a substantial computational task and required extensive use of the ICHEC and ECMWF supercomputer systems over a period of 3–4 years. The project simulated the future climate (up to the year 2100) at high resolution (4 km grid spacing) using the most up-to-date regional climate models, Coupled Model Intercomparison Project Phase 6 (CMIP6) Earth system models and new shared socioeconomic pathway and representative concentration pathway (SSP-RCP) (SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5) emission scenarios. The scenario-based projections are supplemented with global warming threshold scenario projections for temperature and precipitation.

Developing solutions

This research provides Ireland with a data resource to explore its future climate and enables the assessment of the scale of impacts across sectors, at regional and local levels. This report provides an outline of the regional climate modelling undertaken to assess the impacts of climate change in Ireland, based on a number of future scenarios, and highlights the key findings. The project has also provided a large database that can be interrogated for various meteorological parameters, which is essential for detailed analysis across a diverse range of sectoral concerns.

The national climate projections of the current report are in broad agreement with previous research, which adds a measure of confidence to the projections. The research improves on previous research by simulating the future climate at a higher spatial resolution (4 km) using the most up-to-date regional climate models to downscale an ensemble of CMIP6 global datasets under the new SSP-RCP emission scenarios. The increased ensemble size of projections allows for a more accurate quantification of climate change uncertainty. Furthermore, the current report provides projections for additional climate variables and derived metrics that are critically important to biodiversity and to key Irish sectors, including agriculture, health, energy and transport.

This project was funded by the EPA, Met Éireann and the Marine Institute with the lead research organisation the Irish Centre for High-End Computing (ICHEC).

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