How artificial salt marshes can help in the fight against rising seas

Made from Crossrail clay, Europe's biggest coastal habitat restoration project is a valuable flood defence but is itself threatened by climate change

It is the third hottest day on record in the UK and the cool saline mud oozing through my toes provides welcome relief from the beating sun. I am standing barefoot in a shallow pool in Europe's largest coastal habitat restoration project, Wallasea Island in Essex. The 670-hectare (1,656-acre) expanse of salt marshes, lagoons and mudflats was formed using more than 3m tonnes of London clay excavated from the Crossrail tunnel network, almost half of the waste material from the entire project.

In the heat, crowds of flamingos would not feel out of place, but the sweltering temperature is a gnawing reminder of how rising sea levels and the climate crisis will threaten the UK's coastline. The problem is so grave that one Dutch government scientist has even proposed a 295-mile (475km) dam of the North Sea to protect large parts of western Europe.