For the purpose of a story, I'm having an additional island in the North Sea. The island is where the Doggerbank used to be, but a bit larger. The highest "mountaintops" are around 1000m, but a lot of the country is between 1-50 meters above sea level. The island has two mountain ranges. The land usage is mostly agricultural areas, with some larger forrest areas, and several swamp areas. I've provided maps below (except for the land usage) for better visualization.

My question is, how would such an island influence the weather/local climate/tides? My guesses:

  • the mountianranges would probably influence the winds/rainfall considerably, so dryer climates/less rain in Denmark and Germany's north?
  • With spaces between lands much narrowed down, tidal heights would drastically increase, more to what can be seen in the English Channel?
  • the existing Dutch and German islands might be influenced in their existence, as they are sand islands
  • On the new island itself, the lowlands would get a lot of rainfall, while the area behind the mountains would be dry
  • Weather systems would probably take a different course altogether, but I have no idea what that would look like

Is this plausible, or would the changes be different?

EDIT: Added natural currents imposed over new island

EDIT 2: Based on the comment, I also add this question: What do you think is a sustainable island size that wouldn't cause total havoc? Reducing it by half, splitting it up into several islands?

Island in the North Sea

Natural currents

  • $\begingroup$ Perhaps you can edit to include approximations of current conditions without the addition, that would help a lot. $\endgroup$ Feb 14, 2021 at 8:54
  • $\begingroup$ I've added the current currents superimposed over the new island, I hope that is what you meant? I have no idea about the strengths, though, except that the one between Denmark and Norway is really strong, as is the one in the English channel. The seabed in the currents-image is the real thing, btw. $\endgroup$
    – BeeMKay
    Feb 14, 2021 at 9:48
  • 1
    $\begingroup$ oof. good question. if would severely alter and disrupt the air and ocean currents all along the coastline of the North Sea. Possibly even stagnate the oceanic current through the Channel, which would have (huge) knock-on effects on the Atlantic currents, which would....... I shall withdraw, this is way,way above my ability. Don't know how big, but it will be big. I expect it would have knock-on effects well into the Mediterranean. $\endgroup$
    – PcMan
    Feb 14, 2021 at 12:20
  • $\begingroup$ @PCMan, thank you, that was quite a sobering comment. What do you think is a sustanaible island size that wouldn't cause total havoc? Reducing it by half, splitting it up into several islands? $\endgroup$
    – BeeMKay
    Feb 14, 2021 at 14:16

1 Answer 1


Not that much

Deep currents

Honestly because the north sea is so shallow and because the submerged doggerland island is still there, the deep north sea currents will barely be affected. Here are the real north sea currents.

enter image description here

All you really lose is the central north sea current which is pretty minor.

Surface currents

Now these will really be bothered but predictably a lot of the central surface currents just wont exist. you will have the great north sea eddy but widened shifted a little west and that is about it. All this will generate less evaporation so the surrounding areas may be come a little drier.

enter image description here


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