The biggest unknown risk is from what our science does not know or appreciate as a risk. This is from unknown effects that we are not familiar with, or not realising the consequences of a change in something that we already have or plan for.
It may be simple, such as creating technology, or something like a weapon that has a specific role. The effects of that being ‘known’ but the ramifications assumed to be limited, but finding out in the end they are not. This is where something that is assumed to be limited and contained has an unknown additional characteristic which allows it to have a much greater spread and effect. For example, simple chemical agents that get into the system and have longer and more lasting effects than is on the label. Antibiotics and anti-malaria drugs may come into this, where widespread and indiscriminate use prompted nature to find a way around them by force of numbers, so such things as MRSA are generated by the action of blanket use. It was only a matter of time before this happened, the simple idea that a thing could be eradicated by certain actions but not aware of the ‘knock on’ effects of a counter evolution.
I can envisage planned weapons and changes that should be specific to certain targets or plans, but with minor changes because of things like environmental and evolutionary effects, making them more general and a threat to all or many. We can never be sure of all consequences or actions, so should be wary of making large and sudden changes, however beneficial or small the consequences may appear. Causality has a strictly determinable but chaotic effect that means we can never be sure of all outcomes. What’s called the ‘butterfly effect’ is seen as evidence of a chaotic system where one small change makes a large effect somewhere else, but most things are damped, not having these effects where systems tend to ‘normal’ and average, other counter effects coming into place, but time and causality means they may be recorded and perpetuated somewhere in the system, appearing when the original event has long been forgotten. The environment and processes being a long term storage of life and events.
We dismiss history far too quickly. We could not do this, or we do not know of this, so it doesn’t or didn’t exist. The general view by historians is that the ancient Sumerians had a list of kings that lasted 120 sars, a sar representing 3,600 years, which was supposed to be originally the orbital timing period of the planet Nibiru that the Sumerians claim to have come from. If it was orbiting our sun it would be somewhere near 250 AU from the sun, which would be way too cold for life to exist there from normal irradiation froom our sun, but if it was a much larger hotter star natural illumination would not be a problem, but stellar longevity may be. A vastly hotter star would most likely have a much shorter life, burning through its store of hydrogen much faster. An rough estimate of this proportion is about a 2:4:8 ratio. This means that a star that has 2 times the diameter will put out 4 times the radiation at earth distance, have 8 times the mass and an 8th of the lifespan at the same distance.
This means that to get a solar type irradiation at 250AU the star would need to be around 50 times the mass of our sun and a stellar lifetime of about 1 million useful years, so it’s unlikely that Sumerian life would have developed there, but move from a more stable or previous one close by sun. Moving there they would have known that a deluge was coming and prepared for the next move, ‘space hopping.’
But, it could be that this is a simple misinterpretation of the concept of the sar, being one of travelling long distances from something like a remote star at near light speeds, resulting in a sar period representing an elongated time of 3,600 years in normal space.
We have the antediluvian rulers that were in power before the ‘Great Deluge’, a period that was supposed to have lasted 241,200 years, but if we take the view that the original people of Sumer were space travellers on an a type of ark from a dying sun, they could have had a normal lifespan compared to modern man, but to the world outside and the one they came to, the travel in such a worldlet could allow for such an epic time difference. 3,600 years normal time travelling representing 36 years in near light speed time. If the Sumerians were right then we could look to a planet orbiting a defunct star within about 30 light years, or from 2 hops, 60 light years.
The likelihood though is that we developed here, our ancestor species being a fairly continuous line that probably started about 5 million years ago in mid-africa, a parallel evolution that could combine with our own being highly unlikely, so rendering the ‘god’ type combination suspect.