Future Climate Risk Assessment

The TRN is highly vulnerable to climate related hazards and is already experiencing the locked-in impacts of climate change, including more frequent weather-related disruptions and escalating damage to the network infrastructure.

The baseline screening assessment provided an understanding of our current exposure and vulnerability to climate risk on the TRN. The future climate risk assessment builds on the baseline screening, develops the risks identified and assesses them in terms of likelihood and impact. This will estimate the likelihood of a risk event occurring based on analysis of event probability and relevant climate drivers, alongside any assumptions that can be made where climate hazards will have an impact on the TRN.

The Met Office’s most up to date model, UKCP18 climate datasets, were used to assess climate hazards. The datasets provide updated observations and climate projections for a medium-high scenario in the 2050s and 2080s. This allows us to visualise the projected frequency of hazardous climate conditions and the magnitude of their effect.

Development of the future climate risk assessment was further strengthened through analysis of SEPA flood map data, engagement with Dynamic Coast (University of Glasgow) and a comprehensive literature review. Once the forecast data was compiled, risk scores were assigned for nine key hazards: surface water flooding, river flooding, coastal flooding, cold spells, high winds, river scour, landslides, extreme heat, and cascading risks.

The assessment estimated the likelihood and impact of each hazard affecting the TRN. Summary scoring for each risk was undertaken using the risk scoring matrix in Figure 4.

Figure 4: Risk assessment scoring matrix

A summary of key risks is presented in Figure 5 for the 2050s, based on a medium to high emissions scenario (RCP6.0). This scorecard outlines how climate risk will change across the trunk road network by the 2050s, based on the UK’s latest climate change projections (UKCP18).

Figure 5: Climate Risk Scorecard for 2050s

Key risks included increased surface water flooding, river flooding, river scour and landslides due to climate change damaging assets, causing network disruption, and resulting in safety risks. The risk ratings are identified with current levels of adaptation e.g. investment in flood defences and maintenance of drainage systems.

Future climate risk scores were informed by threshold analysis of UKCP18 climate projections. A comprehensive dataset which outlines the future climate risk assessment for each of the hazards can be found in Annex A as an accompanying document.