Our planet has been wiped of life several times in its 4.5 billion year history. The first time was during its creation, since no life could exist on a planet that was mostly high temperature gases and melted rock, with no water and no place to evolve.
The second time is debatable, mostly because it was about 3 billion years ago and things are very difficult to clearly prove about life in the early, tumultuous centuries when planets could crash together to form smaller pieces that formed the moon and more sterile, melted rock and high temperature gases again on the surface of our planet.
But with each new generation of Earth, and thus for the new generations of life forms that evolved here, the traces and clues to what happened are slightly more provable. Myriad asteroid collisions, chemical imbalances, runaway hot and cold periods and "positive feedback" events caused life to snuff out nearly to zero many times over.
Usually, after a bad wipe out, new life forms were free to evolve from the ashes. What once would have been a toxic environment for the majority of species of archaic single-celled organisms might become the preferred soup for the new breeds. The switch from hydrogen or methane based chemistry to oxygen was one of the most severe changes, but was an important one. It resulted in whatever microbes eventually evolved into worms and fish and apes -- thus into us.
But the wipe outs continued. Framed by random punctuations of bad weather, collisions from space debris, runaway feedback events like methane or CO2 greenhouse warming or total ice ages, life had thousands of periods of relative stability. Some of these periods lasted for millions of years, some for only a few thousand years.
Variations in solar radiation can account for some of these periodic catastrophes. There are sunspot cycles today that effect our weather. So are nearby stellar explosions which cause high energy particles and cosmic rays to effect the gases in our atmosphere and thus effect the cloud cover and precipitation over certain periods in history.
All of the events happened in ways that eventually allowed life to never be completely extincted. Maybe 90% of life was wiped out, maybe only 1%, maybe more than 99%. It varied greatly, and all the reasons are difficult to prove since the fossils that remain from eons past are not always helpful in determining the causes of death.
Yet, some events are clearly distinguished by coincident volcanoes, asteroid debris, continental collisions and separations, biochemical changes, methane ice melts, great fires and many other large scale murderers. And there are many cases of animals themselves causing their own starvation by eating all available food to extinction. Usually, obviously, there is not a total starvation, merely a massive reduction in population of the offending glutton, such as when coyotes eat too many rabbits.
But once in a while there evolves some animal that is so successful and deadly that it completely wipes out its food source and that is that. It no longer survives. Most of the great carnivores in the past fit into this pattern, although sometimes bad luck and bad weather helped nail their coffins shut. Sometimes the food source itself is what changes, such as when only poisonous plants are left alive when all non-poisonous plants have been consumed by an unstoppable herbivore.
Sometimes the culprit can be oxygen buildup by photosynthesis, resulting in a great burn-off when certain gases or fuel sources spontaneously combust. Whole forests can be felled by sudden methane releases into a high oxygen environment. Yet seeds might survive the holocausts, allowing rebirth of the forest once the chemistry of the planet has stabilized.
Obvious to all but those with industrial "blinders" in place are the current chemicals and pollutants produced by our modern technological civilization and its ever increasing population of human consumers. We are a very successful carnivore and herbivore. We can even eat bacteria or fungi directly. There are few things we cannot eat, but we can usually eat the things that can eat those inedible things. In short, if we set out minds to it, we could eat the entire planet down to the irreducible rocks, lava and metallic core.
Then what? Once the last shred of edible material had been consumed, then what? Do we eat ourselves ala Soylent Green? That could not last long even if we could lower ourselves to cannibalism without a societal collapse. There are practical limits to the amount of humans that can exist on this planet under ANY conditions. There are even greater limits to the number of humans that can CO-EXIST with other life forms that make life worth living here.
Presumably, by necessity, our species will somehow stabilize at a sustainable population, or we will collapse almost to zero. But we will not grow at the current rate for much longer. Whether the number is 10 billion, 100 billion, or only 1 billion -- I don't know. If other planets can be utilized for mankind, perhaps the higher number is possible. If that is not possible, then perhaps even less than 1 billion is the stable point.
Oil will not last forever, nor will coal or any other kind of fuel that we currently utilize. Nuclear energy might help, especially if fusion reactors are possible, yet almost nobody believes that technology is any less problematic in the long run. Even just the entropy of the system would result in a kind of heat death when the nuclear engines radiated their lethal qualities into the environment. Nothing is free of penalty. 100 billion humans cannot live here without converting the planet into a kind of hell.
Perhaps humans could cut back on their life styles to that of deer or rabbits, but even overpopulations of deer and rabbits has disastrous results. What are the coyotes for the humans? Other humans? Would we result in a "Time Machine" world of Eloi and Morlocks? Would a privileged class of humans simply exterminate "excess" members of the non-privileged class?
I hope not, and think that we are probably not that evil as a group. We would find some other, less hideous method. Just use rational birth control methods -- find ways of balancing our chemical systems with nature -- don't leave all the lights on in all the skyscrapers all the time. There are solutions to a sufficiently motivated population. Bad weather, starvation and the decomposition of civilizations will be highly motivating.
The second time is debatable, mostly because it was about 3 billion years ago and things are very difficult to clearly prove about life in the early, tumultuous centuries when planets could crash together to form smaller pieces that formed the moon and more sterile, melted rock and high temperature gases again on the surface of our planet.
But with each new generation of Earth, and thus for the new generations of life forms that evolved here, the traces and clues to what happened are slightly more provable. Myriad asteroid collisions, chemical imbalances, runaway hot and cold periods and "positive feedback" events caused life to snuff out nearly to zero many times over.
Usually, after a bad wipe out, new life forms were free to evolve from the ashes. What once would have been a toxic environment for the majority of species of archaic single-celled organisms might become the preferred soup for the new breeds. The switch from hydrogen or methane based chemistry to oxygen was one of the most severe changes, but was an important one. It resulted in whatever microbes eventually evolved into worms and fish and apes -- thus into us.
But the wipe outs continued. Framed by random punctuations of bad weather, collisions from space debris, runaway feedback events like methane or CO2 greenhouse warming or total ice ages, life had thousands of periods of relative stability. Some of these periods lasted for millions of years, some for only a few thousand years.
Variations in solar radiation can account for some of these periodic catastrophes. There are sunspot cycles today that effect our weather. So are nearby stellar explosions which cause high energy particles and cosmic rays to effect the gases in our atmosphere and thus effect the cloud cover and precipitation over certain periods in history.
All of the events happened in ways that eventually allowed life to never be completely extincted. Maybe 90% of life was wiped out, maybe only 1%, maybe more than 99%. It varied greatly, and all the reasons are difficult to prove since the fossils that remain from eons past are not always helpful in determining the causes of death.
Yet, some events are clearly distinguished by coincident volcanoes, asteroid debris, continental collisions and separations, biochemical changes, methane ice melts, great fires and many other large scale murderers. And there are many cases of animals themselves causing their own starvation by eating all available food to extinction. Usually, obviously, there is not a total starvation, merely a massive reduction in population of the offending glutton, such as when coyotes eat too many rabbits.
But once in a while there evolves some animal that is so successful and deadly that it completely wipes out its food source and that is that. It no longer survives. Most of the great carnivores in the past fit into this pattern, although sometimes bad luck and bad weather helped nail their coffins shut. Sometimes the food source itself is what changes, such as when only poisonous plants are left alive when all non-poisonous plants have been consumed by an unstoppable herbivore.
Sometimes the culprit can be oxygen buildup by photosynthesis, resulting in a great burn-off when certain gases or fuel sources spontaneously combust. Whole forests can be felled by sudden methane releases into a high oxygen environment. Yet seeds might survive the holocausts, allowing rebirth of the forest once the chemistry of the planet has stabilized.
Obvious to all but those with industrial "blinders" in place are the current chemicals and pollutants produced by our modern technological civilization and its ever increasing population of human consumers. We are a very successful carnivore and herbivore. We can even eat bacteria or fungi directly. There are few things we cannot eat, but we can usually eat the things that can eat those inedible things. In short, if we set out minds to it, we could eat the entire planet down to the irreducible rocks, lava and metallic core.
Then what? Once the last shred of edible material had been consumed, then what? Do we eat ourselves ala Soylent Green? That could not last long even if we could lower ourselves to cannibalism without a societal collapse. There are practical limits to the amount of humans that can exist on this planet under ANY conditions. There are even greater limits to the number of humans that can CO-EXIST with other life forms that make life worth living here.
Presumably, by necessity, our species will somehow stabilize at a sustainable population, or we will collapse almost to zero. But we will not grow at the current rate for much longer. Whether the number is 10 billion, 100 billion, or only 1 billion -- I don't know. If other planets can be utilized for mankind, perhaps the higher number is possible. If that is not possible, then perhaps even less than 1 billion is the stable point.
Oil will not last forever, nor will coal or any other kind of fuel that we currently utilize. Nuclear energy might help, especially if fusion reactors are possible, yet almost nobody believes that technology is any less problematic in the long run. Even just the entropy of the system would result in a kind of heat death when the nuclear engines radiated their lethal qualities into the environment. Nothing is free of penalty. 100 billion humans cannot live here without converting the planet into a kind of hell.
Perhaps humans could cut back on their life styles to that of deer or rabbits, but even overpopulations of deer and rabbits has disastrous results. What are the coyotes for the humans? Other humans? Would we result in a "Time Machine" world of Eloi and Morlocks? Would a privileged class of humans simply exterminate "excess" members of the non-privileged class?
I hope not, and think that we are probably not that evil as a group. We would find some other, less hideous method. Just use rational birth control methods -- find ways of balancing our chemical systems with nature -- don't leave all the lights on in all the skyscrapers all the time. There are solutions to a sufficiently motivated population. Bad weather, starvation and the decomposition of civilizations will be highly motivating.
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