In my fantasy world, there is a peninsula around the size of mexico almost entirely surrounded by mountains about the size of the himalayas which go directly into the ocean. How they got there is magic, it has no relevance to the climate. The interior of the peninsula is dry, if that information is needed.

To be clear, I don't want to know what the climate on the peninsula is, I want to know what effect would this have on the global climate?

enter image description here

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    $\begingroup$ This mountain triangle would block air movement. What latitude this peninsula is at, and which way is it oriented? $\endgroup$
    – Alexander
    Oct 27, 2021 at 18:53
  • $\begingroup$ Climate depends also on the configuration of landmasses and oceans. Without that information we cannot give an answer. $\endgroup$
    – L.Dutch
    Oct 27, 2021 at 19:23
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    $\begingroup$ @Alexander it is located in the tropics, if that helps $\endgroup$
    – Photino
    Oct 28, 2021 at 15:54
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    $\begingroup$ @L.Dutch I added a map of the world with the cold area circled in red $\endgroup$
    – Photino
    Oct 29, 2021 at 18:06
  • $\begingroup$ You should clarify whether the zone is preternaturally cold even at low elevations, or cold only due to high altitudes (like Kilimanjaro, only bigger). Cold air from high altitudes will naturally warm to roughly the appropriate temperature as it descends, per the Ideal Gas Law. $\endgroup$ Oct 29, 2021 at 19:17

1 Answer 1


Yes, large islands (like e.g. Iceland) affect ocean streams like the Gulf stream.

When it is situated in the wrong place, it can change climate drastically. When you would magically introduce an island the size of Mexico in the atlantic, the climate in Europe, Florida and NYC would get colder ! If Iceland would not be there, Ireland and UK would get warmer.


I can't find a location in the northern Atlantic that would not disturb the Gulf streams,

enter image description here

The appearance would cause an enormous Tsunami.

.. how does this island magically appear ? If landing slowly, or pushed up gently, there may not be a problem. If it is dropped off, or materialized (worse case !) brace for impact. Everywhere to 150km off the Atlantic coast.

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    $\begingroup$ Its actually a peninsula, that rose slowly over a few years, which would likely have an impact but that happened hundereds of years ago in my story, so I expect the climate and ocean would have stabilized by now. Thank you for your explanantion of the gulf stream! $\endgroup$
    – Photino
    Oct 28, 2021 at 15:53
  • $\begingroup$ Ok, so it stabilized already.. that will make your world more viable :) the period of climate change has occurred long ago. But it has influence: a very large peninsula, stretching out into the ocean, with the large, elongated shape of Mexico would probably yield instable weather. When it would stick out in east-west direction in the Atlantic Ocean, blocking any ocean currents, you could get a weather boundary, north and south of the peninsula temperature differs. This may result in heavy rainfall and irregular weather patterns. $\endgroup$
    – Goodies
    Oct 28, 2021 at 16:07
  • $\begingroup$ It isn't the shape of mexico, its around the same size, but mostly circular, rough around the edges of course. It goes off the west coast of a continent, if that helps. $\endgroup$
    – Photino
    Oct 28, 2021 at 18:07
  • $\begingroup$ West ? east ? See remark of L.Dutch.. we can speculate a bit about Coriolis directions, ocean currents etc.. but west or east really depends on the topology of your planet ! For me, bottom line is: the answer to your question is (in my opinion) always "yes", a large, (cold or not) island/peninsula will always influence climate. The above is just an example of the reasoning, based on knowledge of weather systems. You'll have to fill in your story.. in your world.. $\endgroup$
    – Goodies
    Oct 28, 2021 at 18:15

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