You can imagine that in a hundred million years, the world map will be unrecognizable, along with the creatures that inhabit the territory. Certain tendencies in Earth’s past may reemerge, like the trope of supercontinents. It is now thought that many supercontinents have come together and broke apart in the deep time of the planet (Rodinia, Nuna, Superia, Sclavia, etc…) You could even imagine that this process is cylical. A few million years into the future and things begin to look completely different, as subduction zones will begin to consume the entire Atlantic Ocean.
As continents close in on each other, all the volcanic island chains will be shoved into mountain ranges, simmering down carbon dioxide emissions and contributing to colder climates and growing glacial masses.
And who knows, before all of that may happen there could be a massive interruption of life from an extra terrestrial impact, lurking from the deep of the solar system. All it takes is a single grain of sand out there in the void and everything we humans have come to enjoy as comfortable living, indeed of an ecosystem capable of supporting life, may come to a hault.
From this perspective, anthropogenic climate change seems a drop in the bucket. Of course it is not that such change spurred on by humans is irrelevant, just that when you consider that more intense carbon dioxide injected into the atmosphere by humans will be ‘washed out’ of the system in relatively short order, you begin to get a sense of how massive Earth forces really are and how inconsequential our hubris may be. In a few milion years all of the anthropogenic CO2 will be taken out of the atmosphere and turned into limestone at the bottom of the sea. As the sun grows brighter over the course of its own intense cycle, the Earth will get warmer even as CO2 dwindles away, and as a result the ice age will come to an end. The world that emerges from this situation will look unrecognizable as the climate will be warm but will lack CO2 to the. The result is that there won’t be much plant life anywhere, or animal life for that matter (as both depend on CO2). This unrecognizable world would have occured without human injections into the atmosphere.
Since CO2 has dropped since the age of the dinosaurs, plants have evolved photosynthetic pathways that adapt to low CO2 regimes. Over the course of a few million years into the future, such plants (like grasses and shrubs) will come to dominate the now hot and generally humid world, while trees and forests will be unable to photosynthesize and will disappear. Earth will become shrubby and in many places barren.
And if you pan out even more into the deep future, say 800 million years from now, you begin to get a sense of a totally barren world. When CO2 drops below 10 parts per million, all photosynthesis will become impossible. As plant life disappears, so go the animals that depend on it for oxygen and food. Proteins will also unravel and mitochondria will break down. This is the final mass extinction.
And long after all life is gone, its memory will be preserved in the fossil records. Of course it is a long shot that anyone or anything will be around to discover them. And so, all of what we have come to know or will come to know in the distant future will become the ancestral…