Axial Tilt of Forgotten Realms?

[Desdichado]

I'm not that impressed with the Traveller books; I'd recommend World-Building instead.

 

[Hawkshere]

That looks real good too. Thanks for the link!

The Traveller stuff probably isn't as detailed -- it's intended for checklist planet construction in a game where you may be generating dozens or even hundreds of systems for a SF game.

 

[Storminator]

not directly, but every bit of information helps. I didn't know about the glacier retreating.

joe b.

But bear in mind that in FR, there's a pretty good likelihood that important geopgraphic features like glaciers and deserts weren't caused by natural forces.

PS

 

[Desdichado]

Yeah, the Traveller books are very much a game supplement. That isn't necessarily a bad thing, but if you're really looking for realism, that's not the best source (IMO.) This book, on the other hand, was designed for SF authors to give them enough grounding in planetology that can stand the scrutiny of a number of geeky SF readers.

 

[jgbrowning]

I'm not that impressed with the Traveller books; I'd recommend World-Building instead.

Reading it right now. And "Aliens and Alien Societies"....


joe b.

 

[Desdichado]

I like that one a lot too!

 

[MaxKaladin]

I seem to remember working this out in 2e, but then they changed the map all around...

 

[Argus Decimus Mokira]

Hey

As pointed out here, axial tilt corresponding to slightly colder weather than Earth is a red herring. The Earth has gone through fairly dramatic climactic swings from the coldest depths of the ice age to the balmy Mesozoic where there was no permanent ice cap at either pole. All of these changes can easily take place without the benefit of changing the axial tilt. If you want to be that serious, you need to probably hire an expert in global climatology and get him to run a bunch of "what if" scenarios. The inputs for climate are extremely complex.

Not quite true ... Earth's axial tilt has, in fact, changed, and continues to do so. The Yugoslavian astronomer Milutin Milankovitch noticed a corollary between changing ratios of oxygen isotopes in deep sea cores and ice ages on the planet surface. The repeating pattern of glaciation occurs regularly in a repeating period of 100,000 years. Smaller periods of 41,000 and 26,000 years were also discovered. Of note here is the 41,000 year period (these periods collectively are known as Milankovitch cycles, btw). Within the span of this cycle, Earth's axis changes from a minimum of 22.5 degrees to a maximum of 24.5 degrees (today we have an axial tilt of ~23.5 degrees, I think ). These changes in in orbital geometry alter the amount of solar energy striking the Earth, and thus affecting global climate. In other words, and I do apologize if I'm coming off as a jerk, the axial tilt of Earth does indeed change, with drastic (ice age-magnitude) consequences for Earth's climate.

Having said that, the warmest periods of Earth history invariably occur when a large circum-equitorial sea is present due to continental drift. This was true of the Mesozoic, which you mention. The Pangean continent rifted into the northern Laurasian and southern Gondwanaland continents by the late Jurassic, with the Tethys seaway between them. Without pole-to-pole continents as we have today, the equitorial currents (powered along by the precession of Earth's rotation) were kept in the tropical regions, and NOT diverted to the higher latitudes (as they are today, for example, the Gulf Stream). This water stays warm, not cooling appreciably, and affecting global climate accordingly.

Now, what does any of this mean for Faerun? Well, firstly the lack of such a circum-equitorial sea would indicate a world-wide climate similar to our own. However, as has been mentioned, has a rather large number of non-mountain glaciers that are rather far south, notably the Great Glacier. This is in part explained away by magic - Ulutiu's necklace and all that. However, the effects of continentalism may also contribute. This is an effect felt in the interior and western edges of the larger continents, where moist air blown on from the oceans are depleted of moisture (and therefore warmth) as the blow across the continent, leaving the said areas arid and cold (see Siberia for a perfect example - the only thing preventing the northeastern US from having such a climate is the Gulf of Mexico). However, there are other glaciers that couldn't be caused by continentalism, like those of Icewind Dale - in fact, the idea of glaciers being there at all is a bit of a stretch. Therefore, I'd go with the colder climate of Toril stemming from a shallower axial tilt than Earth's current tilt, maybe 22.7 degrees or so - it's really guess work. Perhaps the retreat of the glaciers indicates a slight change in the tilt - it is increasing, creating warmer summers which are melting the glaciers.

Sorry for the longwindedness, but I didn't want to just pull 22.7 out of my butt.

Thanks
-Matt

EDIT: Also, lots of other factors could be contributing to Toril's "cold spell" - a less luminous sun than Sol, it's orbit being further from that star than Earth's, a greater libido effect, weaker concentrations of Greenhouse gases, or magic, I suppose. If is makes it easier to have Toril and Earth with the same axial tilt, simply alter one of those.

 

[jgbrowning]

I really appreciate your post. Now I have some names and concepts to look up!


In particular, I found this part of your post the most interesting.................

EDIT: Also, lots of other factors could be contributing to Toril's "cold spell" - a less luminous sun than Sol, it's orbit being further from that star than Earth's, a greater libido effect, weaker concentrations of Greenhouse gases, or magic, I suppose. If is makes it easier to have Toril and Earth with the same axial tilt, simply alter one of those.

hehe


joe b.

 

[d4]

...a greater libido effect...

one would think that would only make the planet hotter!

of course, the word i believe you were looking for is albedo.