Climate change and potential impacts for GB nuclear industry

Research activities

The UK has experienced extreme weather events over the past few decades:

• High temperatures and heatwaves (e.g., July 2022);
• Rainfall (e.g., Boscastle floods, August 2004); and
• Low temperatures and snowfall (e.g. winter 2009/10).

We tasked our Expert Panel with providing us with a literature review on extreme weather events in the UK to address whether the magnitude and frequency of extreme events is changing and attribution of weather events to climate change has been made.

The Expert Panel performed a comprehensive literature review of peer-reviewed papers published in reputable academic journals. Key findings from these papers were synthesised into a technical report submitted to us. To address our questions, the report:

• Defined extreme weather;
• Reviewed methods of assessing extreme weather events;
• Reviewed the record of pre-historical weather events;
• Reviewed the record of historical weather events;
• Reviewed instrumental records of extreme weather events;
• Discussed methodological and technical issues for understanding extreme weather events; and
• Provided conclusions.

The paper found that that anthropogenically-forced climate change can be detected at small temporal scales based on the spatial patterns. However, it is also found that unforced climate variability over the UK region has been high in the past and probably higher than previous research has suggested. This is most likely the case for flooding, where the palaeoclimate and palaeoflood record shows that recent floods may not be extremely large when considered in their long-term context. Extrapolation from only instrumental data sets may not capture the actual risk of future extreme events.

This demonstrates the importance of long-term studies of extreme weather and climate events, if we are to better understand the context within which recent extremes have occurred.

The report identified three emerging topics where additional research would be beneficial to inform our regulatory position:

• Tipping points – a tipping point in the climate system is a threshold that, if exceeded, leads to significant changes in the climate system;
• Model uncertainty – uncertainties in climate modelling are large and this means that the usefulness of outputs needs careful consideration; and
• Compound events – the safety significance of compound events has had little study, and there is a need to understand the applicability of existing methods of analysis and exploring auto-correlations across multiple timescales.

We once again tasked our Expert Panel with providing us with a comprehensive literature review on these topics.  and develop a report for each of them.

These reports are published on the ONR research website. Preliminary findings comprise:

• Tipping points – various tipping points have been identified in earth systems, some of which may have already been reached and others that may occur soon. Risk assessments should consider evidence for potential tipping points;
• Model uncertainty – climate models have been remarkably successful in providing credible large-scale climate projections for many years. However, climate model uncertainties need to be better understood so that future projections are made more robust, and better-informed risk management decisions are made considering these uncertainties; and
• Compound events – temporally compounding events and the impact on infrastructure performance of prolonged sequences of storms is an important consideration, which may not be captured by a design basis event. Our understanding of the reliability of infrastructure, its time-dependent deterioration, and the impact of changing loads is currently limited. The adequacy of the design basis event approach needs to be considered as research into these topics develops.