dinsdag 14 mei 2013

Drying the Gulf of Bothnia (or "Looking in my crystal ball" or "The cause of WWIII")

Sorry, but I could not decide on the title of this blog post. So I tried a literature technique I learned from reading my first "real" dutch literature novel, "Tjeempie! of Liesje in luiletterland", by Remco Campert, which is a typical dutch novel, full of sex and without story (I hope I do not offend anybody now, but I was a teenage boy, just finding out about the two (sex and good stories) and I did not pay a lot of attention to the last). Remco Campert also had two titles so he put them both on the cover of the book. Just like him, I am now among the great dutch literature writers (literature is the art of writing, not the scientific kind, which is also great, but that is not what I want to talk about (In the next bit I will, just to make things complicated, hmmm lets continue)), writing in English, hmmm...

Enough about the title bit (I just needed an introduction), I want to talk about this phenomenon we observe in Scandinavia, or even more accurately  Fennoscandia (We need Finland and part of Russia in this story). The ground is moving up in this area, or as Anders Celsius (Europeans know him from the temperature scale) would record, retreating of the Gulf of Bothnia. He was the first scientist to measure the water level retreat using abandoned seal rocks. Nowadays we don't use seal rocks anymore (Well in the Antarctics, the use of bird vomit is made for measuring ice sheet history, but that is another story). We use a satellite based height observation system, (you all know it) GPS (not the tomtom kind, but better ones). Several campaigns have measured the speed of the uplift of land (because that is what is happening, not the retreating of the sea), which has a vertical velocity of 1 cm/yr in some areas. One of these measurement campaigns is Bifrost (I am linked to them with my research), this is what they see:


The colors, with the legend in the bottom, are vertical velocity observations. Orange being more than 1 cm/yr (10 mm is 1 cm, pay attention in high school). The red arrows are horizontal velocities of the surface. So a circular area that is coming up, and land is moving away from the centre of this area. It is a bit like pressing your thumb on a piece of pencil gum and removing your finger. It takes some time for the pencil gum to reshape in its old form. This is what we call the viscous behavior of the Earth. Because the Earth is not fully elastic it takes some time to react on loads put on it (or in this case, loads taken off it). What load? I will write about that some other day. 

First I told you about new land in my previous post. So, I made a fancy (beautiful colors) figure of the topography and bathymetry (what the Earth would look like if you remove all the water) of the area.  

This is how the area looks like today (well, the color scale is the height of the area). Red area is the Scandes, the mountains on the border of Norway and Sweden. I used blue for areas where there is water. The data I used to construct this map is to be found on the internet (ETOPO2). The Netherlands are clearly visible (It looks like the whole country is flooded, which it would have been without our waterworks) and the British Isles in the bottom left (You will see why I put those areas in the figure). 

Now lets use my crystal ball (matlab program + a good computer. (title, title!!!)) and see what the area looks like after fully relaxation of the Earth (discussions are still ongoing, but this will happen between the next 1000 years or infinity, lets just say 1000 years, because otherwise it takes a lot of time).

I left the black coastlines of today in the figure, to have a reference. But the whole Gulf of Bothnia is disappeared and dried up (title, title!!!). Remarkable is that a bedding of a river can be seen. I did some research and this is called the Eridanos river, an ancient and forgotten river. Another striking observation is that Sweden and Denmark are connected  causing major conflicts between them starting off WWIII (title, title!!!). Not to mention the economical changes in the area, as old shipping routes are cut off (well maybe, by that time we have airborne shipping routes.). And Northern Europe will have its own Great Lake. 

On the other hand, the Netherlands and London, will have sunken even further beneath the sea level. The region, we call North Holland (depicted now in dark blue), will be several meters below sea level. We need even bigger dikes and waterworks (not even mentioning the global sea level rise of 3 mm/yr). This sinking of land is a by-product of the uplift of land in Fennoscandia. Mantle material is needed to fill the void that is created due to the uplift. This material is gathered from the areas around the uplift. The Netherlands is just on the wrong place in the wrong (well not really, this will take some) time.





2 opmerkingen:

  1. Immer diese Weltuntergangsprophezeiungen!?
    Gefährlicher sind immer jene, die weniger sichtbar bzw. offensichtlich sind. Bspw. am Yangtse Fluss Delta. Dort sinkt im erheblichen Maße der Grundwasserspiegel. Noch ein paar hundert Meter und es gibt geophysikalische Erscheinungen - folge wäre für die Region, bei 100+ mio Betroffene, Verschüttungen, Obdachlos, ..
    zu guter letzte, mal ganz unsentimental, für die Wirtschaft wäre das zudem Katastrophal. Dagegen waren die paar wankelnden und kippenden Banken mit ihren monetären Debakel ein Witz.

    Achja, Auswirkungserscheinungen aufgrund von sinkendem Grundwasserspiegel sieht man schon an einigen stellen in Spanien.

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    Reacties
    1. Dear An,

      Yes. I hope you don't mind I call you An (I don't like it to talk to a nameless person). I like the German word 'Weltuntergangsprophezeiungen', it sounds great. But of course I was joking about these doomsday prophecies. The people in Denmark and Sweden are one of the most easy going people I have met. I don't think they will start fighting each other (I think they would build a big fire and drink a lot, just to have another party). But I lured you to this blog, just to make such a comment. And I am glad you are reading my posts and brought up the Yangtze river delta. Not only in China, ground water removal is a problem. Some months ago I was attending a talk of one of my colleagues about the coastal areas of Thailand. Here also the ground goes down and the sea level goes up (which is exactly to opposite thing what is happening in Scandinavia). Just look at coordinates [13 deg 30 min 25.42 sec N and 100 deg 31 min 53.47 sec E] on google maps. You will see a monastery called Wat Khun Samut Trawat. It used to be inlands, only 50 years ago.

      I asked my colleagues if I could write a post about it and they said yes, so I hope you will read it (I think somewhere Sunday it will be finished).

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