[Space] What is the 'Gaia' type of garden worlds like? ('Habitability 9').

[vicky_molokh]

Greetings, all!

Some of you might recognize the term from MoO2. This is a type of garden worlds that is considered to have an extremely high Habitability - in fact higher than the homeworld. Notably, it's meant to represent the kind of condition that (a) allow a higher population cap for a given TL than a homeworld of the same size provides and (b) facilitates even better agricultural yields than our world's.

So I'm curious:
What should a planet be actually like in order to provide such benefits for us Terrans? For the sake of the experiment, assume that the planet's 'wild' ecosystem is loosely derived from and/or fully compatible with ours. It doesn't matter whether such a planet has been terraformed to such a state artificially, made by sufficiently advanced aliens, or just came about through infinitesimally unlikely luckiness.

Thanks in advance!

[sir_pudding]

• Large temperate zone and minimal seasons. Probably by a combination of favorable orbit, low axial tilt and greenhouse conditions.
• Low salinity in the seas; all bodies are freshwater.
• Relatively larger surface area of landmasses.
• Primitive or no development of native pathogens.
• High degree of nitrogenation of the soil.

[malloyd]

Originally Posted by sir_pudding

[*]Low salinity in the seas; all bodies are freshwater. [*]Relatively larger surface area of landmasses.

I suspect the conditions required to keep salinity low - the seas need to totally evaporate fairly often and move somewhere else - would be counterproductive, and you don't want to go too far toward smaller ones, Earth's huge oceans contribute a lot to the climate being nicer. A more even distribution might be nice though - there's a reason the seashore is densely populated and low density areas tend to be continental interiors.

[*] High degree of nitrogenation of the soil.

A somewhat related and not so obvious option - high tectonic activity. Lots of volcanos might not seem that desirable, but they're great at keeping soil mineral levels high, and lots of rich and varied ores do nice things for the non-agricultural sector of your economy too. Losing a city or two a century to massive earthquakes or too close eruptions is a small price to pay really.

[sir_pudding]

Originally Posted by malloyd

I suspect the conditions required to keep salinity low - the seas need to totally evaporate fairly often and move somewhere else - would be counterproductiv.

Not a problem if you just have younger oceans.

[whswhs]

Raise the carbon dioxide level. On one hand, photosynthesis is more efficient with more carbon dioxide; in fact our current level is a bit lower than optimal, and some plants have apparently evolved a new photosynthetic pathway to adapt to this. On the other hand, you'll get warmer temperatures, and I've read that cold is more lethal than heat. Certainly this amounts to a recommendation for global warming, but some of the issues with global warming appear to relate more to the rate at which it takes place and the difficulty in adapting to changing climate and sea level in a hurry than to the absolute levels. Of course you wouldn't want the classic SF Venus, but something like Earth in the Eocene might have its advantages.

[malloyd]

Originally Posted by whswhs

Certainly this amounts to a recommendation for global warming, but some of the issues with global warming appear to relate more to the rate at which it takes place and the difficulty in adapting to changing climate and sea level in a hurry than to the absolute levels.

Change costs somebody money. Global cooling wouldn't be any more welcome.

In the *really* long run, I'm not so sure Golden Age Venus would be going too far. Ultimately if it has more biomass, I'd think a civilization that could control the same fraction of it and redirect it for its own purposes would be richer for it. Differently than we are now perhaps, but better off.

[ericthered]

Originally Posted by whswhs

Raise the carbon dioxide level. On one hand, photosynthesis is more efficient with more carbon dioxide; in fact our current level is a bit lower than optimal, and some plants have apparently evolved a new photosynthetic pathway to adapt to this. On the other hand, you'll get warmer temperatures, and I've read that cold is more lethal than heat. Certainly this amounts to a recommendation for global warming, but some of the issues with global warming appear to relate more to the rate at which it takes place and the difficulty in adapting to changing climate and sea level in a hurry than to the absolute levels. Of course you wouldn't want the classic SF Venus, but something like Earth in the Eocene might have its advantages.

That doesn't sound like Gaia for humans, it sounds like Gaia for crops. Which I suppose is good enough. As long as we can still breathe the air and go shirtsleeve and don't get knocked over by super hurricanes.

[ericthered]

Minimal deserts, mountains, and other "non-arable" areas. Much of the land on earth is locked up in "Useless" deserts. The human population tends to be concentrated on a limited number of "bread baskets".

[tshiggins]

Originally Posted by sir_pudding

• Large temperate zone and minimal seasons. Probably by a combination of favorable orbit, low axial tilt and greenhouse conditions.
• Low salinity in the seas; all bodies are freshwater.
• Relatively larger surface area of landmasses.
• Primitive or no development of native pathogens.
• High degree of nitrogenation of the soil.

I'd go with most of this. The low axial tilt seems obvious, as does high nitrogen content of the soil. There's a lot to be said for properly twisted amino acids, because that means humans can eat the native plants and animals, even though it means the native animals and pathogens can also eat us.

I don't think low-salinity oceans is a viable expectation, but a better distribution of ocean and land would be nice. A dozen or so land-masses the size of Australia, distributed more or less evenly around the planet, might work out well, especially if they were connected with archipelagos. That means a lot of shallow waters teeming with life, and the lack of really huge expanses of open ocean minimizes the intensity of coriolis storms.

I hadn't thought of the vulcanism thing, but that makes sense, too. Also, I'd say no huge extremes in altitudes. No mountains larger than about the Appalachians or the Pyrenees, which result in minimal rain-shadows or other atmospheric weirdness.

Lots of flora and fauna, everywhere.

[sir_pudding]

Originally Posted by tshiggins

I don't think low-salinity oceans is a viable expectation

It's the expectation if you terraform an arid world, until the new seas have had time to dissolve salts anyway, which takes megayears.

I could also imagine biogenic processes that clean oceanwater on a natural gaia.