[WIP] Building a world from tectonics onward

[Tiluchi]

The warm south pole in that model is due to Teacup Ae's eccentricity, which causes stronger seasons in the southern hemisphere; the significantly warmer summers (and generally flat terrain of the southern continent) evidently prevent permanent glaciers from forming, and without that ice-albedo feedback the south pole stays remarkably temperate. Later runs with a formal climate model have largely confirmed this result (though that also helped highlight some of the shortfalls to my approach to determining precipitation).

Thanks for that explanation! And thanks for the great posts on your blog, I recently completed your GPlates tutorial and I'm a Patreon subscriber. I'd missed the bit about Teacup's eccentricity, but that makes sense. A question however about the elevation: it seems that at the poles, elevation and the presence of ice sheets are somewhat endogenous to each other. For instance, most of Greenland would be below 1000 meters above sea level if it weren't for the presence of the Greenland Ice Sheet, which is 2-3 kilometers thick. The high elevation brings temperatures down, which allows for a continuing ice sheet- a feedback loop basically. I'm assuming that Clima-sim or ExoPlasim would give us ice cap climates near the poles if we were to include 2000-meter-thick ice caps in our elevation map inputs. So barring a detailed history of atmospheric CO2 for the world, maybe the presence of an ice sheet is a decision we have to make ahead of time as we're building the planet, rather than assuming from our geology that doesn't take into account the potential presence of thick ice sheets at some of the poles.

What do you think? As I said earlier I'm not really a climatologist, and I don't have either of the simulation programs as I'm using Mac OS, so these are just my educated guesses.

[MrBragg]

Ok, so another interesting tidbit is the comparison between calculations on Earth in January with 1) a starting ice cap on Antarctica, and 2) without a starting ice cap. When the model starts with ice, things look reasonable enough, but when it doesn't... the south pole gets hotter than the outback in the summer. This seems like a spurious result and, even if it isn't, does go to show the massive (50 degrees C!) dependence on the starting conditions.

With Ice (Left), Without Ice (Right)

[Peter Toth]

This is unfortunate as I'm come to rely on Clima-Sim for its supposed accuracy and its ability to automate climate modeling with a consumer PC. Are you changing the CO2 levels or any other parameter between the two simulations? Did you repeat the simulation to verify it wasn't some random error by the processor (if that's at all possible)?

I'm intending to move on to ExoPlasim and I'm wondering if this program is more accurate. I remember morne's experimentation lately that resulted in a desert that extends much too far north, so I'm very skeptical.

By the way, MrBragg, I'm highly impressed by your Wilbur results from a couple weeks ago. I'm experimenting with Wilbur as well to generate some realistic terrain, but I'm not easily satisfied by my results so far.

Looking forward to the completion of your conworld!

Peter

[MrBragg]

Thanks Ottehcnor! At some point I'll cobble together all the different pieces of the methods that I've written about into something that is at least largely coherent.

By way of an update, here's an alpha version of the neighboring continent with some method tweaks to avoid carving out giant river canyons in all the highlands.

[MrBragg]

Another continent is finally in an alpha state. With it, a hemisphere has a first pass of topography

[Turambar]

Another continent is finally in an alpha state. With it, a hemisphere has a first pass of topography

Well done! The level of topographical detail you get zooming in is very rich and realistic. I love it.

[Tiluchi]

As always this is amazing work! Your Wilbur maps have to be some of the most convincing I've ever seen, and hopefully you can post a tutorial at some point. If I have any minor quibble it would be that that southern continent doesn't quite fit in aesthetically with the northern two- I think particularly due to the irregular peninsula protruding northwards. On its own it's quite a nice-looking landform, but it makes it a bit harder to see how those three fit together (as based on your tectonic map it seems they were recently joined as one supercontinent. It's a very minor issue though, and I'm firmly in the "it's okay to move on if you've already put a lot of work into it" camp so I wouldn't worry about it too much unless you foresee some major reworking of the coastlines in the future anyway.

[MrBragg]

I'm firmly in the "it's okay to move on if you've already put a lot of work into it" camp

I increasingly find myself in that camp with you Your critique here is entirely legit; the part where these three were recently a single landmass was an addition that came after I had gotten somewhat attached to the general shapes. My post hoc rationalization for the many little bays and gulfs that don't really fit together is that they're just flooded continental crust. Not sure how plausible that is, but at the time it worked for my geologically challenged brain

And who knows, maybe when I finally finish a first pass of the topography things like this will start to irritate me and I'll get an itch to go back and change things...

[Charerg]

I have to say I'm a little bit jealous of how quickly you manage to build up the topography (compared to my own sluggish pace ), and very nice quality as well. I wonder if you use a similar approach to mine (start at a lower resolution), or do you just build up the topography in a single pass? Looking forward to seeing more!

[MrBragg]

Thanks Charerg! I mostly just use a single pass at the final resolution. I say "mostly" because I do do an initial pass at very low resolution where I mark off regions of "mountains", "lowlands", "really tall mountains", etc, but that's more of a sketch than an actual step in building. I've found this a good balance between wanting nice detail and being lazy