The Government Actuary’s Department and the Institute and Faculty of Actuaries used London Climate Action Week to convene a cross-government roundtable on climate scenarios. According to GAD, representatives from eight government organisations attended to compare current practice and consider how scenario analysis can support policymaking and long-term decision-making. GAD framed the issue in cross-government terms. Departments increasingly recognise that climate risk reaches beyond environmental policy, affecting economic performance, infrastructure resilience, public services and national security.
For officials, the practical question is no longer simply whether climate uncertainty matters, but how it should be built into routine decision-making. GAD said many departments already use scenario-based methods for horizon scanning and strategic risk planning, but the roundtable examined whether those methods are being applied consistently when policy, spending and investment choices are made. That distinction is important. A department may acknowledge climate exposure in strategic planning, while still assessing programmes or estate decisions against a narrow central case. The discussion focused on how that gap can be reduced.
The opening session set out an actuarial approach to scenario analysis. As presented at the event, scenarios are not forecasts. They are structured tests of how a decision performs under severe but plausible futures, including outcomes that sit outside a single most-likely path. The Institute and Faculty of Actuaries also drew on its contribution to HM Treasury’s Green Book discount rate review. The policy relevance is direct: long-term, transformational and highly uncertain decisions may require a different appraisal approach from routine investments. Where climate adaptation is concerned, the appraisal method can shape which interventions appear proportionate and which do not.
Participants then moved into facilitated discussion on where climate uncertainty is already well considered and where it is still overlooked. According to GAD, the exchange focused on barriers to wider use of climate scenarios across government, including governance arrangements, analytical capacity and the availability of tools that can be used more consistently between organisations. This matters because climate impacts do not follow departmental boundaries. If departments work from different assumptions or different levels of analytical maturity, it becomes harder to compare risks, sequence interventions or maintain a coherent case for long-range investment.
GAD used separate work with the Ministry of Justice on prison estate overheating risk as a practical case study. That analysis examined how rising temperatures could affect the prison estate and how scenario techniques can be used to test the performance of possible responses under different future conditions. For policy officials, the significance of that example is operational. It shows how scenario analysis can inform estate management, resilience planning and capital decisions where the direction of risk is clear, even if the timing and severity of future pressures remain uncertain.
The timing of the roundtable reinforced the point. Deputy Government Actuary Matt Gurden said the event moved to a hybrid format after a Met Office red heat alert during a period of extreme heat, providing an immediate demonstration of climate risk affecting working arrangements as well as longer-term planning. The roundtable did not produce a formal new standard, but GAD said it identified a shared interest in stronger governance, better analytical tools and closer collaboration between organisations. For departments preparing long-horizon policy, estates or infrastructure decisions, that is the part of the discussion most likely to shape follow-on work.