#thessia

It's been said that geography isn't destiny. That is true, to some extent ; it should be best to say that geography sets a stage and dictates conditions in which it is easier - or more difficult - for life to thrive or perish.

Temperature, Landmasses and Humidity

At 25°C for the average temperature at sea level, Thessia is warmer than Earth by nearly 10°C ; nonetheless, an abundance of water has resulted in greater overall rainfall and the oceanic climate being much, much more prevalent than on Earth (though the other biomes, from tundras to hot deserts, also exist), and a greater total area of fertile, arable land relative to Earth — even though Thessia's total landmass is actually smaller than Earth's. The reason is topography : most land on Thessia is close to the sea and smaller than Earth's landmasses, with very little of the harsh continental interiors one finds on Earth.

Thessia's warmer climate wasn't caused by more carbon dioxide or other greenhouse gases in the atmospheric mix, relative to Earth, but by three other factors :

Thessia is closer to its parent star, Parnitha, than Earth is to Sol, at 0.94 AU ; both stars are G2V's, generating a broadly similar amount of light and heat

while both Earth and Thessia are still undergoing a glaciation - since on both planets there are permanent ice sheets at the poles - on Thessia, most of the icecaps cover oceans, not landmasses, and remain well past both the Arctic and Antarctic circles ; as they are thinner by necessity, the result is that most of Thessia's water is not locked away in ice

there are far less mountain ranges running from north to south on Thessia than on Earth, allowing the winds carrying moisture from the ocean to go much deeper inland

The result is a surfeit of islands and reefs, many inland seas, and seven small, broadly interwoven continents.

An unforeseen beneficial effect of such natural serendipity is that Thessia's climate is very stable : whenever Thessian flora has absorbed too much carbon dioxide, the resulting cooling of the climate led to the expansion of the icecaps, the appearance of glaciers and the lowering of sea levels, thereby reducing the total amount of Thessian flora… allowing carbon dioxide to rise again and warm up the climate back to its starting state.

Sur'Kesh, meanwhile, has the same average temperature as Thessia ; but as it is even wetter, with far more water vapor in the air than on most regions of Earth, it usually feels hotter than either Earth or Thessia. These wet climates allowed the moisture-reliant amphibian-like clade that would eventually give birth to the salarians to thrive and out-compete rival clades also emerging out of the oceans, whereas in other conditions such animals would have suffered from an insurmountable disadvantage.

Sur'Kesh's lower atmosphere contains both more oxygen and more carbon dioxide than Earth's, though not in quantities which would put the health of an alien visitor at risk. The atmospheric mix, which has a lot to do with the development of the planet's climate and biosphere, remains broadly stable by dint of a carefully monitored equilibrium between fauna and flora.

Thanks to how warm and wet Sur'Kesh is, the primary characteristics of the salarian homeworld are great landmasses covered by lush rain forests separated by large oceans : jungles are the most common type of ecosystem on Sur'Kesh, stretching much further north and south than on Earth, and there are few actual deserts in the warmest latitudes. Sur'Kesh's temperate bands, meanwhile, reach almost to the poles.

That is because of Sur'Kesh's resemblance to Earth during its Cretaceous period : unlike Earth or Thessia, Sur'Kesh has no ice at the poles, and its distributed continents are broken up in such a way that the oceans are free to circulate warmth along the east/west axis at all latitudes — resulting in the temperature gradient between Sur'Kesh's poles and equator being very shallow. Furthermore, three of Sur'Kesh's continents are connected by land bridges and align on the equator, resulting in a fairly large biome along the east/west axis, warmed by the equatorial current on its long northern shore.

In consequence, the winds on Sur'Kesh are very light (outside of the monsoon season wherever it applies), and the oceans tend toward stagnancy, with little upwelling.

This climatic homogeneity is also enabled :

by few tall mountain ranges (or at least, by few mountain ranges on coasts which would create a rain shadow),

by a thick atmosphere (at 1.42 atm), enabling more transport of heat relative to Earth,

and by an axial tilt close close to 0°, resulting in very little seasonal variation during the Sur'Kesh year, though seasons still occur — the festival of Betau, for instance, marks the end of winter in the southern hemisphere.

Impact of Geography on History

Compared to humanity, asari civilizations developed with far greater ease in jungle islands and peninsulas, irrigable floodplains on every continent, and along the coastlines and in the archipelagos strewn all across the planet. This greatly influenced asari history, as agriculture developed in far more places than on Earth (i.e. China and the Fertile Crescent) and prehistoric sailors navigated across the entire breadth of a world whose geography fostered maritime trade and the exchange of ideas in a network of coastline villages.

The same couldn't ever be true of salarian civilizations : as freshwater amphibians, seawater is deadly to them. Instead, salarian societies developed along river basins first and then laterally through jungles to other river basins ; the historical importance of the basin as the basic geographical unit is evident in the name salarians chose to give to their home cluster, the Annos Basin. Sur'Kesh's geography was changed further by the many canals and artificial lakes ancient salarians dug up as they built their dams, mounds and lodges. Those waterways, both natural and artificial, were the primary avenues of transportation and communication for most of Sur'Kesh's history, conveying both people and goods during times of commerce and war. The development of sea travel, which developed out of fishing practices, was eventually but belatedly spurred by demographic pressures in the original continent salarians evolved in.

ACKNOWLEDGEMENTS

I've wanted to imagine what Thessia and Sur'Kesh look like for a long time. While I'm happy to say that Sur'Kesh owes mostly to the books I read (particularly Thomas Halliday's Otherlands), I could never find a set-up which suited Thessia, as I wanted the planet to be a warm paradise unlike Earth that would foster decentralization and exchange while keeping its canonical ice caps, with my broad initial idea being that Armali and Serrice would be on a cluster of large islands like the Arctic Archipelago but much closer to the equator, perhaps linking two continents — that is, I couldn't until I discovered the imaginary Earth known as Seapole, which is in no way mine. Thessia as I imagine it is Seapole, and I could never have come up with it on my own ; I heartily encourage you to check it out and support the author if you can (or like).