When people talk about the impact of rising sea levels, they often think of small island states that risk being submerged if global warming continues unchecked. But it’s not only those on low-lying islands who are in danger. Millions of people live by the sea – and are dependent on it for their livelihoods – and many of the world’s largest cities are on the coast. By 2050 the number of people living in delta cities is set to increase by as much as 70%, experts suggest, vastly increasing the number of those at risk. To shed light the impact of rising sea levels, we are taking a close look at two very different cities, Rotterdam and Maputo , and their varying responses to the problem.