The Changing Level of the Baltic Sea during 300 Years:
A Clue to Understanding the Earth

Martin Ekman

Summer Institute for Historical Geophysics, Åland Islands, 2009
ISBN 978-952-92-5241-1
Hard cover, 155 pages, 10 tables, 40 figures

Description of the book (from its back cover)

This is a book about the sea level of the Baltic Sea. It might seem as a very specialized subject. In fact it is not, on the contrary. The fascinating thing is that this single physical quantity – the Baltic Sea level – tells us a lot about the planet we live on. The Baltic Sea has the world’s longest series of sea level observations. From the Baltic Sea level, as observed during three centuries, we are able to draw conclusions about the behaviour of our Earth: its interior, its oceans, and its atmosphere. Thus, historical data from the Baltic Sea are used to solve modern Earth science problems of a more global character. This is the fundamental idea of the book.

Moreover, the book gives a historical perspective on discoveries and solutions of the sea level problems. Things are explained by describing how they have actually been found out (or not found out), starting from the very beginning, sometimes commenting on old results from a modern point of view. Original scientific sources are used throughout. This means throwing light also on important works being long since forgotten by modern scientists.

Finally, in order to broaden the outlook in somewhat unexpected directions, some special aspects related to the sea level changes are included at the end of the book.

This book spans several Earth sciences, from solid geophysics through oceanography to climatology. It is intended for reading by a wide range of geoscientists or other people with a professional interest in the Earth and its changes.

Table of contents


  1. Introduction: What is so interesting about the Baltic Sea level?
    1.1 Remarkable phenomena
    1.2 Remarkable data
    1.3 The world’s longest sea level series
    1.4 Sea level relative to what?
  2. Is the land going up or the water going down?
    2.1 Harbour problems and relocation of towns
    2.2 The scientific use of seal rocks
    2.3 Sea level marks and their significance
    2.4 The first land uplift map – one that was never constructed
  3. Postglacial rebound and the interior of the Earth
    3.1 The discovery of the Ice Age
    3.2 A new possibility: Postglacial uplift?
    3.3 Sea level gauges: Uplift rates and the marine limit
    3.4 The viscosity of the Earth’s interior
    3.5 Mareographs: Mapping the uplift rate
    3.6 Modelling the mantle, crust and ice of the Earth
  4. Climatic sea level rise and the glaciers
    4.1 The water level at the sluice: A change in the rate of change?
    4.2 Melting glaciers and sea level rise
    4.3 Sea level rise and global warming
  5. Winter sea level changes and the atmosphere
    5.1 Reversed currents and the water-works
    5.2 Winds or air pressure?
    5.3 Storms and short-term sea level variations
    5.4 Persistent winds and long-term sea level variations
    5.5 Winters and the varying seasonal sea level variation
    5.6 Long-term sea level and changes of winter climate
    5.7 Short-term sea level and another change in winter climate
  6. Pole tides and the rotation of the Earth – and the atmosphere once again
    6.1 The discovery of polar motion
    6.2 The search for the pole tide – and the surprising result
    6.3 Polar motion or winds?
  7. Mean sea level and the sea water itself
    7.1 At what height above sea level is sea level?
    7.2 Mean sea surface topography and salinity of the sea water
  8. Some special effects
    8.1 The world’s oldest preserved sea level gauge
    8.2 Saving a parliament from the postglacial uplift
    8.3 Historical shore levels and Viking ship jetties
    8.4 Sea level and the economy of the royal water mills
    8.5 Sea level and the winter that never arrived

Appendix: The Stockholm sea level series 1774 – 2000

References (in chronological order)