How would a very old biosphere differ from Earth's "young" one?
On my world, the equivalent of the Cambrian/Avalon explosion happened 5 byr (2 byr after formation) ago as opposed to 0.5 byr ago on Earth.
The planets rough parameters are:
mass between 0.4 and 0.25 Earth-masses
only 10 to 30 percent global ocean cover, water is mostly near the poles
orbits a 10.9 Jupiter-mass warm super-Jovian
extensive vulcanism and some plate tectonics
the global average temperature is 63 C, just shy of a runaway greenhouse effect given the local atmospheric pressure of 2,7 atm
only one atmospheric circulation cell due to slow rotation (the moon is tidally locked)
long days and nights (still need to do the math, assume one terra-week each)
the sun is an old F-type with only a few hundred million years left on the main sequence
So how would this planet's 5 byr old biosphere and environment be different from Earths young one in a broad sense?
I´m aware that this could easily be considered as too broad or opinion based, but I´m only looking for macro details. For example, I think that the planet would have very extensive fossil fuel deposits, a very diverse tree of life, an environment where life has adapted to very exotic niches (cloud-algae for example),... .
This post was sourced from https://worldbuilding.stackexchange.com/q/151291. It is licensed under CC BY-SA 4.0.
1 answer
The planet's life-forms have gone through several stages:
Natural development, natural environmental factors such as repeated ice-ages and extinction level events have produced over a significant timeline - a diverse range of species. Particularly in isolated island environments - much like Birds-of-Paradise, or Chichlid populations have developed on Earth.
Intelligence emerges dominant over it's natural predators. The predominant life-form has developed intelligence and culture to the point of sapience, agriculture and animal husbandry. Significant areas of land are used for crops, increasingly tending towards mono-cultures, as immunity to various pests is sought. Animals are bread, the natural stock's diversity of genome is subsumed by the need to develop commercial "big and muscular" stock that breed fast without hassle.
Industrial revolution. Vast swaths of natural resources are used to power the transformation to an industrial society, commerce exerts it's pressures. The atmosphere begins to change.
Pollution, extinctions, sudden climate change, drought and famine become global issues as the climate sways towards the unstable.
The dominant species gets a grip and re-balances the bio-sphere in a way favorable to the survival of (predominantly themselves) life on your planet. Somewhat through nano-tech, some through the transformation of energy usage, some through bio-engineering. (This is a phase of great danger to your dominant species) Many extinctions, and the chance of utter failure must be dealt with.
The entire bio-sphere is engineered to take advantage of all the incident energy from your star and the geo-thermal energy. This is done (quite automatically by means of biologically engineered micro-organisms) to take advantage of every niche that an organism might fill (see convergence of biology and engineering). Your entire planet is engineered to be optimal for life, and life is engineered to be optimal for the planet - perfect synergy.
This is only one possibility of how the planet's development might occur, and any development after this point would delve even further into speculation. The alternatives would seem to either be that intelligence doesn't develop, it does and destroys itself or gets wiped-out before it has sufficient power to prevent it. There seems sufficient time in your scale for it to die-out and re-develop several times. It would seem inevitable that if it survives, it should have extended off-planet maybe even a couple of billion years before the end of the time-scale that you suggest.
0 comment threads
0 comment threads