The argument continues whether global warming is caused by man or nature, but whatever the cause, there is little argument that it’s happening, and that sea levels are rising. The global average is 1/14 inch (1.8 mm) per year. As warming increases, computer models predict that a one-meter rise in sea level is likely (over 50% chance) to occur over a period of two hundred years, and could even occur as soon as the year 2100. The impact of such an incredible rise in sea level should not go unnoted by any oceanfront or tidewater property owner.

As discussed in The Public Trust Doctrine In Motion, the boundary between the upland and public trust land is an “ambulatory” line in response to slow, gradual, imperceptible changes. Thus, as sea level slowly, gradually and imperceptibly rises over time, the waterfront boundary will slowly but surely creep more and more landward, decreasing the amount of privately owned land on any affected parcel.

It is also interesting to note how sea level rise may affect places far from and above the ocean – like Idaho, for example. In Chapter I, the case of City of Coeur D'Alene v. Mackin brought to us the folks living on Sanders Beach in Coeur D’Alene, between 11th and 15th streets, who wanted the beach to themselves. The Supreme Court of Idaho, however, ruled against them, holding that the public has the right to enjoy the beach from the ordinary high water mark (OHWM) down, which had previously been determined to be 2128 feet above sea level. But, as the real ocean’s level rises, and Idaho keeps the OHWM at the same 2128 feet above sea level, slowly, year after year, the OHWM will get higher and higher – even though the actual lake level remains the same. Thus, every state in the Union that sets the ordinary high water mark for a waterway at a fixed elevation above actual sea level will be affected. As the real sea level rises, up go all of the fixed elevation OHWMs, and consequently, up go the boundaries of the public’s trust beaches and shorelands all around the Nation.

See The Public Trust Doctrine In Motion for a more thorough discussion of how the Public Trust Doctrine becomes important as the sea level rises.