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Press release

How 3 locations, 5,000 miles apart are working together to tackle climate change in North Wales and Zanzibar

View from the Old Customs House,Zanzibar Stone Town Heritage Society
View from the Old Customs House, Zanzibar Stone Town Heritage Society | © Sharida Diaz Gautier

From the Atlantic to the Indian Ocean, three sites join forces to withstand coastal change and share experiences through a unique twinning project by the International National Trust Organisation.

What does Porthdinllaen and Penrhyn Castle on the North Wales coast have in common with Zanzibar, an island off the coast of east-central Africa? They are over 5,000 miles (7000 km) apart, but all three locations are impacted by climate change, including rise in sea levels, coastal erosion, heavier and more frequent storms or cyclones, flooding and damp issues.

The impacts of climate change are not limited or constrained by national borders, that’s why the International National Trust Organisation’s (INTO) ‘Withstanding Change’ project involves the National Trust alongside five heritage organisations in the Middle East and East Africa, all of whom are working in areas where the impacts of climate change are already pronounced.

As part of this project, which is funded by the British Council’s Cultural Protection Fund, National Trust Cymru are working with Zanzibar Stone Town Heritage Society (ZSTHS) to help each other identify climate hazards, the potential impacts on heritage sites, as well as adaptation options at Porthdinllaen and Penrhyn Castle.

Dewi Davies, Project Manager, National Trust Cymru said;
“Like many sites along this stretch of coastline, the beautiful and very popular harbour village of Porthdinllaen is under threat from the impacts of a changing climate. Here, though, it is not only the rising of sea level coupled with storms of increasing frequency and ferocity, but also landslides and slope failure, exacerbated by increasingly frequent and intense rainfall events that threatens the village.”

“Over several years we have been working with partners to bolster the village's resilience against high tides and storms – including installing tidal flood boards and increasing the height of the sea walls along the front – so that when the sea threatens to inundate, properties here will have a fighting chance of defending themselves. The cliffs behind have also been given an engineering makeover drained and pinned so that when heavy rain falls, the risk of slope failure is greatly reduced.”

The coastal settlements of Stone Town and Porthdinllaen have always faced the challenges of their inherently vulnerable locations head on, only now the need to adapt is greater. This twinning partnership has meant that teams in North Wales have been able to share experiences and learning with partners in Zanzibar, providing a mutually beneficial way of working together on climate change solutions.

Ceri Williams, General Manager at Penrhyn Castle, National Trust Cymru said;
“This twinning opportunity with the Zanzibar team will give us at Penrhyn huge opportunities for learning and for reviewing our own plans. For several years we have been working towards addressing the impacts of climate change on the castle; in particular, the higher levels of water we are seeing on site and the effects of storms. The work that the Zanzibar Stone Town Heritage Society have done with their communities in upskilling people with traditional heritage skills is of particular interest.”

“As Penrhyn Castle is part of the Slate Landscapes of North Wales, a UNESCO World Heritage Site since 2021, I feel we can learn a lot from our partners in harnessing the passion and interest of our local communities whilst ensuring we are embedding the necessary skills in the local area to preserve these globally significant parts of the world.”

The Stone Town of Zanzibar is an outstanding example of a Swahili trading town, with Arab, Indian and European influences visible in the eighteenth and nineteenth-century buildings, including The Old Customs House, listed as a UNESCO World Heritage site in 2000.

Hoshil Dhanji of Zanzibar Stone Town Heritage Society said;
“Located on the Mizingani seafront, The Old Customs House is constantly exposed to increasing humidity and sea salt spray, which deteriorates its external lime-based render and limewash. We're also seeing increased salt corrosion to metallic building elements, including the corrugated iron roof.”

“Frequent pluvial floods saturate the foundations, accelerating the capillary rise of moisture-borne salts which evaporate and force the salt particles to the surface of plasters, renders and washes. This causes spalling, flaking and peeling. Increased out-of-season rainfall is preventing the walls from drying out and leading to growth of algae, as well as deterioration of timber elements in the building.”

The conservation charity believes it’s important not only to mitigate against climate change by working to reduce carbon emissions, but that they also adapt by making their historic and beautiful places more resilient to the effects of climate change – as set out in the conservation charity’s new climate adaption report, launched in November 2023; A Climate for Change.

‘Withstanding Change’ is an International National Trusts Organisation project, funded by the British Council’s Cultural Protection Fund, in partnership with the Department for Digital, Culture, Media and Sport.

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Withstanding climate change in Zanzibar and North Wales

National Trust Cymru have released a new video where viewers can find out more about this unique twinning partnership.

A group of people sat at desks watching a presentation in meeting room

International National Trusts Organisation (INTO) 

Discover which countries offer free visiting arrangements with similar heritage organisations.

The exterior of Penrhyn Castle on a sunny day

Penrhyn Castle and Garden 

Castell ffantasi gyda sylfeini diwydiannol a threfedigaethol | Fantasy castle with industrial and colonial foundations

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A view of the beach and coastal hamlet of Porthdinllaen with the coast visible on the right, a green cliffside behind the hamlet and people visible walking along the beach


An old fishing village perched on the end of a thin ribbon of land stretching into the Irish Sea.


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