Sea levels have been rising and falling without any help from humans for as long as Earth’s oceans have existed. The fastest and most alarming sea changes to affect mankind occurred at the end of the Pleistocene Ice Age. Seas rose about 130m about 12,000 years ago, at times rising at five metres per century. Sea levels then fell as ice sheet and glaciers grew in the recent Little Ice Age – some Roman ports used during the Roman Warm Era are now far from the sea even though sea levels have recovered somewhat during the Modern Warm Era. Many...