"We sit in different teams but combine forces for a richer way of assessing impacts," says Sarah Winne, describing how different departments in Arcadis combined forces to produce contaminated land screening software.

Winne, associate technical director – climate change adaptation, Arcadis, says there is a huge demand for climate risk services as impacts are being felt globally and in different sectors, and are having social and infrastructure implications, which are affecting supply chains. "It is inescapable. Businesses need to understand what these changes mean for their people and value chains, and better prepare."

Stakeholders’ expectations of how climate change is considered are rising due to an increase in public awareness. Employees ask more questions, investors and shareholders want information in greater detail and are asking whether they can withstand climate changes. In many cases, looking at climate risk is now mandatory, arising from the Environmental Impact Assessment Directive (2017) where the vulnerability of projects to climate change has to be included.

There is a requirement to understand climate risks and disclose that information with the Task Force of Financial Related Financial Disclosures (TCFD), the International Sustainability Service Board and the Securities and Exchange Commission. Different governments are also requiring climate change risk assessments and public disclosure.

But in this space, there’s a risk of treating climate risk as a tick box exercise, says Winne. "I would encourage organisations to go beyond the mandate and ask what value it can bring, and to start new conversations."

Winne says the UK Climate Projections (UKCP 18) is available at a granular level and Representative Concentration Pathway (RCP) scenarios are powerful tools to how climate change manifests itself. It is the central part of risk assessment.

However, she stresses that considering only this will leave a lot of questions unanswered. "Working with a non-climate person, people can dazzle them with maps, but they ask what does this mean? It is better to take a multidisciplinary approach and ask what the implications for the sector or the region are."

Winne referred to an example of a client who is working on turning petrol stations into electric charging stations on a European level. Electricity network specialists were engaged, along with local experts with an understanding of the relevant site locations, technical specialists with detailed knowledge of the sensitivities of refuelling infrastructure and existing adaptation measures, and geotechnical engineers (for landslides).

"The result was a richer, more insightful assessment of the potential climate risks, which provided recommendations of potential measures to improve the resilience of the sites and gave the client confidence in their investment."

Contaminated land

Katy Baker, senior technical director at Arcadis, says she was interested in what ‘so what’ means regarding climate change. "If there are changes – what could happen? How can contaminated land specialists use their knowledge to predict what could happen in future?"

There was a growing indirect expectation for climate change impact to be considered when assessing land affected by contamination (e.g. National Planning Policy Framework for England, Well-being of Future Generations (Wales) Act 2015).

But from July 2023, direct expectation for climate change impact is to be considered when changes were made to the non-statutory guidance Land Contamination Risk Management (LCRM), which underpins the assessment of any site in England, Wales and Northern Ireland affected by contamination.

Requirements include: "You should also consider how climate change might impact your site."

"Risk assessment evaluation criteria are the parameters used to judge whether particular harm or pollution needs further assessment or is unacceptable. The exact choice of evaluation criteria will depend climate change and extreme weather events could influence their choice".

If mean temperatures increase, questions have to be asked about how contaminants could move and affect receptors. For example, is there a greater risk of VOCs released to air? Could climate change affect the land contamination risk profile?

Some of the Arcadis’ work built on the white paper prepared by the Society of Brownfield Risk Assessment (SoBRA) Guidance on Assessing Risk to Controlled Waters from UK Land Contamination Under Conditions of Future Climate Change, Version 1.0, released in August 2022.

The Sobra sub-group won a Brownfield Award for the free guidance, which explored what changes were most pertinent from a land contamination perspective.

The guidance looked at factors such as a change in temperature affecting groundwater level elevation, land drying and cracking leading to vertical migration paths; reduction in surface vegetation changing drainage pattern, and increasing flow, reduced volumetric flow rate; creation of perched water tables and reduced dilution.

Baker says, "Site setting and use is critical. Is there the potential for any changes? Take contamination in shallow soils – is it going to be covered by buildings that are going to be protected? So, a site-specific approach is needed. Then which scenario, timescale, and what is the potential for climatic changes."

The Arcadis model concentrates on temperature and precipitation. With regards to temperature, a key question is what will be the increase in average annual mean temperature? Will there be an increase in the frequency of extreme heat events, or an increase in wildfire risk and periods of drought? And on precipitation, will there be an increase in extreme rainfall events, and an increased risk in all forms of flooding and coastal erosion?

So, what are the risk assessment options?

Baker notes there are three routes which could have been taken in this example, the first being qualitative risk assessment based on a review of forecasted changes, which is the SOBRA approach. The challenge here is the degree of subjectivity and consistency in application.

Or a fully quantitative approach could be taken, which would involve fully assessing the impact of projected changes in subsurface. For example, if there is a 3-degree surface temperature increase then below ground temperature, and whether it changes volatility, has to be assessed. This is put into a model and assessed for increased or decreased risk.

Arcadis has settled on the semi-quantitative approach. The Arcadis’ Climate: CLEAR (Climate Contaminated Land and Environment – Adaptation and Resilience) is an in-house GIS tool based on a risk ranking approach – so quick decisions can be made on a site causing concern. The climate change experts look at projections, timeframes, and which probabilities and sensitivities to concentrate on. The land contamination experts ask: if the changes took place what could the output be? And how that annual change could affect land contamination Conceptual Site Model – including flood risk.

Changes in temperature and precipitation are evaluated along with interrelated effects like heave and flooding. It combines the projected changes in climate under reasonable case and reasonable worst-case scenarios with information about the site and its setting to rank the effects on land contamination risks.

It uses a 1-5 scoring method with the likelihood of change and different scenarios. It is subjective scoring but tied to knowledge of changes. The output is a simple matrix with two columns – a reasonable case assessment and reasonable worst case assessment based on actions not being met. It doesn’t capture everything, but is intended to be used as an early form of screening. It helps with LCRM and in the planning process, and looks at the climate change impact to be considered.

The system has a red, amber, and green status, with red being the potential for risks from land contamination to change significantly as a result of climate change impacts; Amber represents risks from land contamination expected to change from climate change impacts; and green implies no notable change in risks from land contamination.

Baker notes that it would be good to work with the engineering geology community to take the next steps forward, looking at heave and ground foundations.


Winne says there are multiple drivers to understand climate risk, especially as the impacts of climate change are starting to be felt: "The impacts of climate change will affect land and the built environment in multiple ways. To understand those potential impacts requires the expertise of climate specialists to explain the changes which could happen, and the likelihood of such changes and the expertise of those involved with land and built environment management to predict the consequences of the projected changes.

"As consultants it is easy to work in silos, but only by adopting this multidisciplinary approach can we understand the potential risks to land and the built environment from climate change. Ultimately this will allow the development of better solutions to build resilience to climate change."