Estimations of local effects of predicted future sea level rises due to melting ice caps like the ones made by David Vaughan, of the British Antarctic Survey, are made more difficult due to the observed land rise of the subarctic landmasses in North America, northern Europe and Siberia, and further acerbated by the sinking of parts of Europe notably the densely populated southeastern England and parts of the Netherland.
From the perspective of a Londoner there is good reason to be worried about possible rising global sea levels, however, the future outlook of a Glaswegian would be much more positive, at least in relation to rising seas levels, and the dwellers of subarctic northern Sweden would have reason to exclaim - what sea level rise? The land is rising!
Dr Vaughan discussed the scenario of 1 metre rises in sea levels within the next 90 years, which seems likely if a recent report on the observed warming of West Antarctica from 1957 to 2006 of 0.1C per decade is correct and possibly more in areas far away from the Antarctic in the northern hemisphere due to the reduction of gravitational pull on the water in the oceans exerted by the ice masses around the Antarctica.
However these predictions were evidently made without counting in the effects of postulated land rise of the Antarctic continent post glaciation or indeed the observable post glacial land rise that the parts of the northern hemisphere that were covered by kilometre thick ice during the last ice age 10,000 years ago are experiencing right now.
The mass of ice that is covering the Antarctic and Greenland at present and covered parts of the northern hemisphere land mass 10,000 years ago, besides influencing gravitation also acts through the pressure exerted, of the tremendous mass on the land it overlays by buckling the earth’s surface and depressing the landmass through the deformation of the under laying mantle made up of viscous materials.
The de-glaciation over the last 10,000 years followed by a rise in global sea levels have shaped human history through the cutting of land bridges like the one that joined Tasmania with the Australian mainland or Siberia with Alaska or England with continental Europe: but in other places land previously covered by kilometre thick layers of ice has actually risen and is still rising. This is the phenomenon called post glacial rebound. The measured land rise can be up to a metre per century and is noticeable in the life time of a person dwelling on the shores of the Gulf of Bothnia. Unfortunately the rise in land in northern Europe is associated with a sinking of adjacent land that was not covered by ice.
The Gulf of Bothnia in the northern part of the Baltic Sea is an area where the post glacial rebound was first observed and described by the Swedish scientist Anders Celsius who in 1765 correctly attributed the observations of the receding sea along the coast of the Baltic to land rise and not to sinking sea levels. Recent GPS technology has allowed the land rise to be more accurately estimated to be 11mm/year in northern Sweden. This has consequences in that the northern part of the Gulf of Bothnia within the next 500 years will form an inland lake due to the formation of a new land bridge between Sweden and Finland across Kvarken, the narrowest part of this shrinking inland sea. Some have advocated the building of a bridge or a dam across Kvarken to speed up this inevitable closing of the sound that separates Sweden from Finland.
The economical reason for these bold plans are to connect the thriving towns of Umeå in Sweden and Vaasa in Finland but also the possibly for Sweden and Finland to get access and sovereignty over a fresh water lake of 24,000 km2 containing the equivalent of more than 200,000 Sydney Harbours of fresh water. This lake would be continuously replenished by the major rivers flowing in from the mountain range between Sweden and Norway and would be easily accessible by ships or a pipeline to take the water to central Europe. Both methods are being used, or are in the development, for the transport of natural resources right now across the Baltic e.g. the transport of gas from Russia to Germany and iron ore from northern Sweden to central Europe.
Londoners who are living on the low lying lands of the Thames river valley and have to face land subduction in response to the land rising up in the north are contemplating increasing the height of the Thames Barrier, or building a completely new dam of similar dimensions to the proposed Kvarken dam at the mouth of the Thames to protect themselves from inundation. Meanwhile land owners on the coast of the Gulf of Bothnia are continuously having to move their boat moorings and over a few hundred years old harbours and towns once at the mouth of the major rivers that flow into the Gulf of Bothnia have had to be relocated further out to the newly formed coast line.
So while a real estate agent in central Victoria can advertise land for sale by that old truism “They don’t make land anymore” and not face legal action for misrepresentation, his Swedish colleague on the coast of the Gulf of Bothnia would know that the land owner on the shore of the Baltic sea can claim new land from the receding sea and thus increase his/hers land holdings within his/her lifetime.
Land is indeed continuously being created by the action of geological forces sometimes in form of major upheavals like volcanic eruptions but other times in form of land rise due to other dynamic processes in the earths crust. The rising global sea level is a problem for many people living close to the sea and potentially a real problem for Australia. But obviously the relocation of displaced people from South Gippsland or the lower lakes of South Australia to the new shores of the Baltic sea is not a practical solution. This is something that has to be solved closer to the homes of those robbed of their homes and their land by the rising seas.
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