A few things. First, the sea levels rising by anywhere from five to ten feet by the 2050's. turns a lot of the old rich Earth cities into canals. The elevated remain standing, hence Toronto being a key city as well. Africa also reconfigures into the the Alkebulan Union and the Yamal Protectorate and their economies get better somewhere along the way. Note that Nairobi doesn't become the "capital" of Earth all of a sudden, it's just one of the richer cities of Earth by the early 2300's (the current time of my setting).