Venice is threatened by rising sea levels and Mediterranean storms. In the next hundred years the sea level of Venice’s lagoon is expected to rise by 20 inches (about 50 cm). Old buildings, churches and cultural sites are in danger of collapsing .
Every year autumn and winter storms flood much of the city, especially places where tourists like to go, like Piazza San Marco, the central square of Venice. The situation has become worse because of the giant cruise ships that sail into the city. Waves push up mud and sand which erode wooden piles on which the buildings stand.