[WIP] Building a world from tectonics onward

[worldbuilding pasta]

So I tried this at T42 and starting with glaciers did converge to a marginally cooler overall temperature at 300 ppm CO2 (22.4 C vs 22.9 C). Starting with <=200 ppm CO2 resulted in a snowball, though, so the hysteresis caused by starting with glaciers may constrain the accessible final temperatures somewhat.

You might try running it first at 300 ppm for 10-20 years and then reduce co2

On a somewhat related note, @worldbuilding pasta, do you have any experience running resolutions >T85? For giggles I tried everything larger and each and every one immediately crashed before the model even got going, even when using an identical input from T85 (only resolution and sra inputs changed) that worked fine.

I haven't even done a proper T85 run yet, I wanna test it more but I've sort of paused my exoplasim work for the winter because of the energy costs here. It might be a ram limitation or something, it might need more layers, or it might be the same bug people have been having with t63 that I still have yet to investigate.

[MrBragg]

You might try running it first at 300 ppm for 10-20 years and then reduce co2

Yeah, if I were super ambitious I could try that, though my results at ~120 ppm CO2 I think are already decent enough to move forward. I've already baked my ice caps into the terrain anyway, so as long as the EPS output gets close I'm happy.

It might be a ram limitation or something, it might need more layers, or it might be the same bug people have been having with t63 that I still have yet to investigate.

Ok cool, those were my first thoughts as well. Going to 15 layers didn't affect it and the error I got was different than when I tried T63, which very clearly told me that that resolution wasn't supported. For memory, EPS at T42 doesn't seem to use all that much RAM (I have 64 GB) and I can run a T85 and a T42 simultaneously, so assuming memory usage scaled ~linearly then I'm imagine at least T106 should be able to run. Next time I run a T85 I'll pay closer attention to the memory usage during the cycles and make sure it never spikes higher than I'd expect.

I haven't even done a proper T85 run yet, I wanna test it more but I've sort of paused my exoplasim work for the winter because of the energy costs here.

If it's at all helpful, I could run some calculations for you when my computer is open, so just let me know.


EDIT: OK so I did some more digging and for T106 and T127 it looks like EPS is missing files it needs for those resolutions. For T106 for example, it starts out with the message "/home/users/.local/lib/python3.6/site-packages/exoplasim/plasim/run/most_plasim_t106_l10_p16.x...." and then crashes; for T85 and T42 this step passes almost instantly and then the model begins. It turns out that the t106_l10_p16 (resolution_levels_processors I'm guessing is the nomenclature) file isn't present in the requested directory and neither are any files associated with T127. So, unsure if this is an issue on my end or with EPS, but figured I'd post it here in case it's useful.

[Charerg]

Overall looks pretty good. Getting the pressure zones right is always a bit tricky, especially over the continents. But while I might have done some things a bit different, you're definitely on the right track. I'll probably post something in the way of more detailed feedback once you get to the later stages, keep up the good work .

[Josh Foreman]

Really great work! I'm going through the same process on my world so it's good to see how others are approaching it. I'm no expert enough to give you any good feedback other than "keep it up!"

[MrBragg]

I'll probably post something in the way of more detailed feedback once you get to the later stages, keep up the good work .

Good job building suspense I'm currently working on figuring out / fighting with Wilbur so I can have at least a crude hiehgtmap before moving on to the next steps that require rough elevations. This--together with figuring out what geography is appropriate for the various regions--is taking me a fair bit of time, so it might be a little while before I get to the next stages, but I'll definitely appreciate any feedback whenever you're able to provide it

Really great work! I'm going through the same process on my world so it's good to see how others are approaching it. I'm no expert enough to give you any good feedback other than "keep it up!"

Thanks! Encouragement is very much appreciated!

[NethanielShade]

I love this thread! Always great seeing other maps starting with tectonic plates. The ocean currents look really familiar, any chance you used Artifexian's tutorial whilst making those?

[MrBragg]

Thanks for all the kind words! It's definitely a rabbit hole, or maybe more of a black hole... ;-)

any chance you used Artifexian's tutorial whilst making those?

Glad you like the tectonics! I've actually revised things a bit since the last post about them, so at some point I should post the updated model. For the currents, I actually used the guide on this forum (https://www.cartographersguild.com/s...ad.php?t=27782) together with looking at maps of Earth's currents like this (https://upload.wikimedia.org/wikiped...erless%293.png).

[MrBragg]

Ok, so I created a criminally-simple outline of topography and, with that as a base, took quite a few stabs in the dark and made temp / precip maps. Doing the temperatures felt ok, but I have much less confidence in the precipitation maps since a lot of those felt kind of like voodoo; in a lot of places there doesn't seem to be enough rain, but I don't really have a lot of intuition for what's reasonable here. In any case, here's what I came up with:

Criminally-simple topography (colors in 1000 m increments)


Temps: Jan / Jul


Precip: Jan / Jul


I fed these into the climate script and, after hunting down some subtly mis-colored pixels, got a result. I haven't spent much time mentally processing this to find things that don't make sense (or editing out the abrupt transitions), but figured I'd put this up here to solicit thoughts. In particular, if anyone has thoughts on the precipitation maps and where I'm missing rain, I'd love to hear them

[Charerg]

Well, I went ahead and did my take on the currents and the pressures to get an idea of how the climate patterns should turn out in my view. The oceanic circulation ended up similar to the one you did, with some differences here and there. Keep in mind that doing ocean currents for a fantasy world is a matter of interpretation to some degree, so this isn't necessarily "more right" than the original. That said, feel free to adopt whatever features you like.

Currents:

 

In regards to the atmospheric pressures, it's largely the same story: the overall pattern is similar to the pressure maps you made, with differences here and there (some of them affected by the slightly different currents).

Pressures:

 

January:


July:

So, looking at the climate maps, the temperature maps are probably ok, but the precipitation could definitely use some work. Looking at the climates, this turned out to be an extremely arid world, which probably doesn't make sense with these landmasses. The first thing that pops out is the equatorial dryness, the areas covered by the ITCZ should receive vast amounts of precipitation. Although looking at the topography (which is criminally simplistic, indeed ), you appear to have a lot of coastal mountains (maybe a bit too many, some of those could be partially island arcs, for example), but I still think the interiors would receive more rainfall than 0-10 mm during the wet season.

Especially the eastern continent, which doesn't have giant mountains all along the coast, should be a lot more wet along the equator. The mid latitudes seem suspiciously dry as well, even well past actual desert latitudes. Some polar steppes turn up right along the coastline of the southern continent, which doesn't seem a likely scenario. So I'd say you could definitely increase the precipitations almost everywhere beyond the desert latitudes (20-30s).

[MrBragg]

Wow, thanks for the detailed feedback! I'm glad someone else agrees that my precipitation is messed up I think I'm clearly missing something, so back to reading for me.

In the meantime, you gave me an idea re: getting rid of some of the coastal mountains. In relatively recent geologic history I have the eastern coast of the west-central continent being a retreating subduction zone, so I think there's at least some justification for turning that Andean range into a bunch of back-arc basins and island arcs. I sketched that change in and also went ahead and amalgamated your current / pressure ideas with mine, so here's where things stand while I work on figuring out what I'm messing up with the precipitation.

Currents


Jan / July Pressure and Winds