What If Humans Go Extinct?

Think about this: Thanos snaps twice and humans disappear. What happens next? Thinking about an Earth without mankind is an intriguing question that many might have pondered but haven’t put serious thought into. Author and journalist Alan Weisman, in contrast, certainly has.

Let’s start with large cities––arguably the most artificially altered land. Considering that humans are the lifeblood of cities, the lack of our species would create almost immediate change. For one, large cities like New York City and London require constant pumping to divert rainfall and rising groundwater that may seep from old rivers, through bedrock. In fact, the MTA reported that "pump rooms draw 13 million gallons of water out of the system citywide” on an average day. Days with considerable rainfall would greatly increase this already large number. Current day pumps require a fair amount of human monitoring; engineers hypothesize that subways would be completely flooded within 36 hours of our disappearance, an incredibly short time for such damage.

Similarly, glitches in oil refineries and nuclear plants would go unchecked due to the lack of human oversight, which is a significant hazard of nuclear explosions and massive fires. Regrowth of the landscape after a massive fire could take centuries, while radiation may remain for millennia.

Another source of long-lasting damage to our planet would be a direct result of our ignorance to protect our environment––our excessive use of plastic and other non-biodegradable materials. We would leave mountains of waste that would persist for thousands of years, poisoning, trapping, cutting, and harming other species in numerous ways.

Yet another source of waste is petroleum, which would seep into the ground at industrial sites and factories. Petroleum, however, is biodegradable. Though the process will take decades, it will eventually be reused by plants and microbes. This will be done via the process of bioremediation, through which microorganisms detoxify or remove pollutants by degrading the hydrocarbons in petroleum. The process is currently used for cleaning oil and petroleum spills in factories, but considering that it is a natural process, it does not require human assistance to initiate. Unfortunately, the same cannot be said about human-made chemicals such as polychlorinated biphenyls, used in hydraulic fluids, heat transfer fluids, lubricants, and plasticizers. Though the use of these chemicals is economically beneficial because they are very stable mixtures resistant to extreme temperature and pressure, it is detrimental to the environment.

On a more positive note, the eradication of humans brings to mind an increase in vegetation and wildlife. Winter snows and the lack of de-icing due to the absence of humans would lead to frequent cracks in the pavements and roads. These cracks would then shelter weeds and other plants. The same would happen to other infrastructures such as bridges and buildings, with vegetation eventually taking over the structures. In fact, Weisman claims that in only 500 years, streets would become forests.

Just like vegetation, wildlife would claim back what once belonged to them in a relatively short time. Even during coronavirus-related lockdowns, animal invasions started to make an appearance, with animals such as mountain goats in Wales and wild boar in Barcelona roaming the streets.

Of course, there are many variables, such as when the mass extinction occurs, the power of technology at that time, the probability of wide-scale explosions, and unforeseen climate changes, that impact what the outcome would be and how long it would take. While some outcomes may see our land full of vegetation and wildlife in 500 years, others may see the destruction of unattended human constructions such as factories, nuclear plants, and pumping systems. If the previously mentioned explosions on industrial plants do occur, the planet’s carbon dioxide levels would increase significantly. Though marine plants would help recover the balance of atmospheric gases, there is only so much that the ocean can do, limited by how much it can acidify itself without harming marine life. Another variable to consider is when the mass extinction of humans was to occur. There would be no mishaps with pumping systems, nuclear plants, or factories if technology and Artificial Intelligence were powerful enough to run them. If programmed bots were responsible for roaming the streets, removing weeds, and de-icing pavements, nature may not be able to overpower these human-like beings. This creates the chance that the planet would continue as it does today without the presence of humans.

While these are fun hypotheticals to consider, the extinction of humanity is not likely to happen anytime soon. Rather than spend a great deal of time pondering what would happen if we were to suddenly disappear off the surface of the Earth, it’s much more worthwhile for us to devote ourselves to solving the problems of our society and to creating a better planet––for ourselves and future generations.