our reporter, michael l wetze, went to jakarta to f find out more. ♪ michael: it's been a whihi sincesquen northern jakarta. the sea has long since claimed it. it m makes irvan pululungan fefd every time he sees the building. irvan: the sinking of the city is increasing in the past few years. and it touches me a lot because, you can imagine, people say their prayers here before, and they cannot do it anymore. michael: the indonesian capital of jakarta is home to over 30 million people. it's one of the most densely populated cities in the world. and it has a problem. the threat isn't obvious here in the heart of the city. but it's severe. in the nororth, home to many fishing communities, there's no ignoring the rising seawaters. this breakwall was built in 2002 in the muara baru district as protection against flooding. the sea wall is continuouslyly being rereinforced and raised. but that doesn't help. after a spell of heavy rainfall, the water begins pouring over again. jakarta is sinkining. irvan: when the groundwater is being extracted very much, and we lose our water catchment, the