Energy, News, and Climate / Science

Winter Is Coming: Oceanography in Game of Thrones

The new Game of Thrones season is right around the corner, and I know one UndertheC blogger who is really excited! It’s me. I’m really excited.

One of the driving plot points through the entire series is the season differential that George Martin’s world has to deal with. Unlike the annual cycle that our Earth goes through, wherein summer occurs for three months every year, and winter for three months every year, the seasons in Westeros last for years at a time, and no one there has figured out a way to predict when one will end. You can imagine this makes things like saving food for winter – or undertaking a land war in Asia – quite difficult. There’s been quite a few posts floating around the internet attempting to explain this phenomenon using science like planetary rotation and gravitational pull. I’m going to add to these posts with an explanation of my own focusing on oceanography. I’ll ask you to forget the futility of explaining a fictional, magical world with the scientific principles of our own world and instead ask you to try to remember that science is fun and can also be magical in its own way.


If you’re unfamiliar with the way seasons work on our planet, I’ll remind you that the principle causation is the tilting of the Earth on its axis. The northern hemisphere experiences summer when the planet has tilted itself towards the sun, and winter when it is tilted away. This is less of an effect of the distance from the sun, as it is a changing of the angle of incidence of the sun’s rays hitting the Earth. When a part of the Earth is tilted toward the Sun, the rays will hit the surface more directly causing generally higher temperatures and a season of ‘summer.’

It follows that if a planet did not have an axial tilt, the annual seasonal variations as we know them would cease. Other explanations for the Song of Ice and Fire’s abnormal seasons are based on adjusting this tilt, and superimposing it with other tilts, from the gravitational pull of satellites or other large bodies in the surrounding solar system. I don’t like these explanations because eventually there would begin to emerge a pattern, however complicated and decadal it might be. Most, if not all, motion in a solar system is cyclic. You can think about our tides, which are often groups of interacting gravitational pulls of the sun and moon. Their sizes and frequency tend to be different at different places and at different times, but we have been able to recognize the pattern and predict their behavior accordingly. I would not like to suppose that the Maesters of the Citadel are inept in this way, so I think there must be some other factors at work in their seasonal cycle.


Obviously this map of the world of ASoIaF is speculative, but it’s the one that I like the best, and the one that best supports my argument here (irresponsible science). So there’s two main differences between this makeup and the one of our own world. The first is the amount of land compared to the amount of water. We have two large oceans (Atlantic and Pacific) that reach – almost – all the way from the North Pole to the South Pole but are fairly contained longitudinally. I cannot stress upon you enough the importance of this in circulating water (and the heat stored by that water) across latitudes. The ASoIaF world, in comparison, has somewhat smaller landmasses. Which brings me to my second point- the land masses here are predominantly horizontally oriented. Westeros does reach nearly all the way up to the North Pole, or we can suppose. But there doesn’t really seem to be another land mass reaching to the South Pole of this planet: I would put the Red Waste around the equator, and Sothoryos at a more temperate region below the equator, but still not reaching any high latitude. The horizontal orientation of Essos isolates the Shivering Sea, keeping it from circulating its frigid waters to the rest of the world. This is analogous to our Arctic Ocean, but much larger.

I think that the winters experienced by those in Westeros are more like mini ice ages than anything else. Essos does not seem to experience the winters nearly as much, and the Summer Islands obviously never seem to see any season other than summer. An isolated polar ocean like the Shivering Sea can contribute to the growth of ice sheets because it never sees any of the water warmed by the sun, like that in the Summer Sea. This shutdown of thermohaline circulation across these oceans is a fairly accepted cause of ice ages in our own world. An ice age ends for multiple reasons, but a slight warming can begin a glacial melt and again shutdown ocean circulation due to an influx of meltwater, causing a positive feedback loop, moving the globe into an interglacial period.

All this to say, ice ages can be a natural cycle of any planetary model with land and oceanic masses. The ASoIaF world, because of its geographic makeup could be affected by small ice ages more frequently but at lesser magnitudes than our own Earth. The seasonal variation might be attributed to magic by the citizens of Westeros, but they aren’t exactly known for their meteorological study. I’ll be watching on Sunday, when Game of Thrones Season 4 premieres, and unless you hate everything fun, you will too. Happy Game of Thrones season – Valar Morghulis.

3 thoughts on “Winter Is Coming: Oceanography in Game of Thrones

  1. Hey, I really appreciate when a scientific analysis is made of my favorite series of books. (I’ve read a similar one theorizing of wine-making in Westeros due to the lack of seasons.)

    I like your premise that Westeros has in general mild seasonal change, but there are these rapid and unpredictable ice-ages that represent seasons in the minds of the people. (Please correct me if my paraphrasing is incorrect.)

    Right on, thanks for posting this!


  2. Pingback: UndertheCblog top ten: In honor of our 100th post | UNder the C

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