All models point to an end times with rising temperatures, continuing disappearance of various life forms, and evaporation of the oceans . And the day will come when the last survivor of all living organisms will die. It will be very similar to the first form of life that appeared on the planet: a unicellular being. But many things will have happened before.
In a few tens of thousands of years we will find ourselves before a white planet. The sea level, whose rise is so worrying today, will fall, revealing new coastlines, uniting islands with continents and turning gulfs into prairies. Survivors of a now-defunct civilization will not need to use the Channel Tunnel ; They can walk to Dover… if they can stand the cold. The few humans alive are likely to huddle around campfires in equatorial zones. We will be in the next Ice Age, worse than the one endured by Cro-Magnons and Neanderthals. Many scientists think that it is starting now.
The era of fossil fuels will be a mere legendary memory, like that of a time when the planet was much warmer. The global warming that lasted a few centuries, destroyed agriculture and caused erratic fluctuations in the climate was a mere sigh in the history of the planet. Slowly, natural processes found a way to reabsorb the carbon dioxide released into the atmosphere. The return to “normal” conditions lasted a short time. Humanity, which flourished during a brief interglacial period, will feel in its own skin the true nature of the planet, the same that has been felt during the last 3 million years: the reign of ice. Humans will live in a colder and, paradoxically, drier world . The forests and jungles will have disappeared, becoming savannahs, the granaries of the world will be dry lands, and the winds will blow fiercely at 200 kilometers per hour, whistling through the plains that the ice will inexorably cover. Little will remain of what one day was the presumptuous civilization that believed to dominate the planet : not even its proud skyscrapers will remain standing, demolished by columns of ice half a kilometer high. Survival will be more and more complicated; You will have to fight too much to feed yourself. Our descendants will be starving.
But the disappearance of Humanity will not imply the annihilation of life. Millions of years after the final death rattle of the last human being is lost in the atmosphere, life will continue its course towards Ragnarok. As in this final battle of Norse mythology, whose final outcome is already written, who will live and who will die, the fate of life is also predetermined.
As the Sun slowly but surely gets 1% brighter every 100 million years , this will cause a continual rise in temperature. Due to this, the levels of carbon dioxide in it will decrease, which will end up in the oceans or in carbonate rocks. According to scientists James Kasting and Ken Caldeira, in 500 million years carbon dioxide levels will have fallen by 40%, photosynthesis will have practically disappeared and 95% of plant species will be on the verge of extinction. Only cacti and shrubs will be able to survive in these conditions. In 900 million years there will not be enough carbon dioxide even for them. Perhaps some other form of photosynthesis capable of sustaining plant life has appeared, with an atmosphere with oxygen on the verge of disappearing forever. From a bird’s eye view, the Earth will be nothing more than undergrowth, taiga, plains, savannas… The planet will be changing the color green to brown.
For their part, in 500 million years the animals that still exist will have to face the lack of nutrients and heat. When the global temperature of the planet exceeds 38º, it will begin to die from the equator and multicellular animals will migrate towards the poles. Above 40º on average (which implies that in the tropics it will be much higher) or new species have appeared capable of withstanding such heat or animal life will face extinction: above 45º degrees the cellular mitochondria stop to work. Life, cornered near the poles, must be nocturnal, hiding from the dangerous Sun. Perhaps there are animals that hibernate during the summer to wake up in the winter from the continuous night. As the temperature rises, animal life will subsist by burrowing. Only bacteria can be found on the surface . When the average 50º is reached, the extinction will be practically total on land. Protozoa, nematodes and flatworms will be the kings of creation accompanied by lichens and mosses. Life in the sea will last a little longer.
Within 1,200 million years the Sun will be 15% brighter, which will cause the surface temperature to reach 70º C on average and practically all the carbon dioxide will have disappeared from the atmosphere. The global circulation system of the oceans will have stopped , so the planetary thermostat will be off. A few hundred meters below the surface of the sea, life would be impossible to maintain due to the absence of oxygen and nutrients. Looking at the sea we will not see fish; we will be facing a dead sea, except for the blue-green algae. They were the first and will be the last in the history of life. The color of the sea will have changed due to the reduction of plankton and an increase in the amount of sediment carried by the waters and the great dust storms: it will be brown.
Accelerated evaporation from the oceans will increase ambient humidity. The higher the water vapor, the higher the temperature, and the disappearance of the oceans will accelerate. Dead by the high concentration of salt, they will leave behind immense salt flats. In the barren landscape that surrounds us, no complex life will be present . Only the ubiquitous bacteria will still be there, as in the beginning of everything. But not for much longer. UV radiation will sterilize the surface and perhaps a few can hide underground.
This is how the Earth will face its irremediable end.
