Walls or the wall, that is the question
A world with multimeter sea level rise is likely to be a world riddled with storm surge barriers. One cannot with certainty tell if or when our world will experience such magnitudes of sea level rise, but we can infer that certain geographical locations offer alternative options to local storm surge barriers. Here, the Baltic Sea is discussed. The Baltic Sea is connected to the open ocean by the narrow and shallow Danish Straits. Closing these straits would require building a seawall of about half the length of the longest seawall in existence today. Closing the sea would create a freshwater lake, a configuration the Baltic Sea had until about 8000 years ago. Given that the scale of the seawall needed to enclose the Baltic Sea is smaller than a number of seawalls already in existence, it is argued that the question is not if an enclosure could be built, but at what magnitude of sea level rise its construction would be preferable to other adaptation measures with smaller environmental footprints. It is found that different countries would likely have different opinions about this given their differing levels of exposure.