Hypothetical - new land ownership
<p>I am intentionally not specifying a country for the following as I am interested in answers for different countries.</p>

<p>Lets say that instead of global warming we would have global cooling - the ice caps grow, seas shrink and with them a lot of land is uncovered. Who owns the new land uncovered in such a scenario?</p>

<p>We don't have to imagine shrinking seas.  New land is created all the time by volcanoes.  The answer is that the ownership of the new land depends on the circumstances.  It may become part of an adjacent parcel, depending on how the deed is written.  More than one landowner might have a reasonable claim, in which case there will be a dispute and perhaps a court action.  There may be no landowner with a valid claim, in which case the land would pass to the government.  There may even be multiple governments disputing each other's claims.  This actually happens, of course, and can lead to anything from insignificant diplomatic wrangling to war.</p>

<p>New land is not only created by volcanoes, but also manmade, for example by the dutch, or it appears almost by itself at the north sea coast of Germany, especialyl around coast protection constructions around some of the islands. Who owns the land?</p>
<p>In the case of the german north sea coast, it is owned by the commune (or rather: Bundesland) and automatically part of the Nationalpark Wattenmeer that was formative in making it. The rules about the national park regulate that this land can't become private property as long as it is part of the national park. Private landowners can't make claims on the national park, but they can request to buy the land from the commune, which then has to request to take that part out of the national park from the authorities above it... it's a long process, but it happens.</p>

<p>In the United States, this is a non-issue because US constitutional 
law doesn't care about "land", i.e. dry dirt, it cares about territory. The standard interpretation is that "federal lands" are owned by the citizens of the US, but held in trust by the US government. Congress has the authority to sell, buy, lease or give away federal lands. Indian tribal lands are a slightly more complicated matter: that is not federal land, that is the land of the particular tribe, held in trust by the US government.
If a lake dries up and becomes "land", the ownership question is based on ownership of the territory. It might be state land if a lake in a state park dries up; it might be my uncle's land if the lake on my uncle's farm dries up.</p>

<p>The complicated question is, what if the oceans dry up (never mind the obvious problem with that hypothetical): what are the boundaries of each nation? In principle, any nation can declare anything to be "their rightful territory". International law recognizes a number of distances for various purposes, the outermost being about 400 miles (the continental shelf). If Russia claims such new land and defends that claim, Russia owns it; if the US does, likewise. </p>

real-estate ownership hypothetical