How to save Venice from rising sea levels? As revellers flock to Venice to celebrate its iconic carnival, local authorities have a much more worrying concern. The Serenissima is one of the world's most beautiful cities, but also one of the most fragile. The Italian city on the lagoon is increasingly threatened by rising sea levels, which are exacerbated by climate change, and is frequently hit by flooding. If nothing changes, Venice could disappear underwater by the end of the century. Our correspondents report on the protective measures the city has put in place.