Cliff recession monitoring at Hunstanton, north Norfolk

Climate change is a topic discussed with rising urgency as the world tries to avoid the tipping point, when it will be too late to act. Mott MacDonald’s coastal management team is helping the fight on the frontlines, undertaking projects to address rising sea levels and increasingly frequent and severe storm events. But the effects of climate change are complicated and the challenge lies in navigating waters where the only certainty is uncertainty.

“In many respects, people around the UK coastline already think about the associated sea level rise and how that will impact on them,” explains Peter Phipps, Mott MacDonald’s head of geomorphology and coastal management. “But over the whole of the UK there’s a very great diversity in predicted sea level rise.”

“In the south east of England recent scenarios indicate exponentially rising sea levels of 4mm per year up to 2025, increasing to 15mm per year from 2085. That’s a metre over 100 years. But in parts of Scotland, because of past ice sheets, the earth’s crust is lifting upwards, so the net impact is significantly less. There are certain places where sea level rise could potentially be neutral, or even fall. It’s very complex. When working with the coast the challenge is trying to understand the variation and uncertainty associated with climate change.”

Coastal management itself aims to integrate different environmental, physical and human factors in order to optimise coastal resources in a sustainable manner. Such resources could include providing or enhancing a rare habitat or maintaining a natural sediment supply from eroding cliffs for a vulnerable low lying adjacent area.

Management methods vary from schemes involving traditional hard coastal engineering on eroding coastlines – including the implementation of rock armour defences or sea walls – to softer, broader management of the coastal zone. Such approaches can include community initiatives for sensitive practices of grazing restriction and prevention of local aggregate removal on low lying sand or shingle ridges, which undermines the integrity of natural protection. Another approach is sympathetic replanting and renourishment of natural coastal systems to enhance their robustness. There is often a range of management options in any one location and when selecting the appropriate approach – given the unpredictability of climate change – it’s a job that needs to account for a vast number of factors and scenarios.

“What you need to do is understand how the climate change scenarios can potentially affect the environment you’re dealing with,” says Peter. “You consider whether a coastal system will be sensitive to change and evaluate the nature and magnitude of change that may occur. Rather than applying systematic cause and effect models in a mechanistic way, you look at how natural systems may evolve over time against a range of possible scenarios.”

Work delivered by our coastal management team includes assessing coastal erosion impacts in the Western Isles in Scotland to protect vulnerable communities and infrastructure in one of the rarest habitats in Europe. The team found that six sites were severely damaged and left vulnerable to further erosion and inundation by the sea following a major storm in January 2005. The sites were subject to full project appraisals for funding applications under the Coast Protection Act.

“The devastating results of the storm in the Western Isles make the whole climate change issue real,” says Peter. “It’s not just sea level rise, it’s the change in storminess and magnitude of events that may have been a contributing factor to the major coastal erosion in the Western Isles. With increasing frequency of these currently rare events, you encounter the extremes that can cause a significant impact. These extremes need to be accounted for in design and management issues on the coast.”