Top Ten Ways Humans May Cause Their Own Extinction

The Earth’s resources are limited. Given our increasing population, resource shortages could lead to major global crises. Many experts think that oil production has already peaked, or will peak no later than 2040. The good news is that past predictions have been countered by new technologies and reserves. The bad news is that fossil fuels are a finite resource: they have to run out eventually. Another source of potential crisis comes from food and water shortages. Currently, 1.2 billion people lack access to potable water. Pollution and climate change threaten to increase that number and severely limit agricultural production. Such shortages could spark resource wars with the potential to broaden into global conflicts.

Why haven’t we encountered intelligent extraterrestrial life, when there are billions of planets in our galaxy? One proposed explanation is that civilizations inevitably destroy themselves when they become too technologically advanced. This scenario was explored in Kurt Vonnegut’s novel Cat’s Cradle, in which the fictional material “ice-nine” crystallizes all water on Earth. So far, fears of experiments turned apocalyptic have proven unfounded. The first nuclear tests did not ignite the atmosphere and ion and hadron colliders haven’t created false vacuums or black holes – yet. Nor have self-replicating nano-bots eaten the Earth. But as we pursue ever more sophisticated experiments in molecular and particle physics, is there a danger of unforeseen consequences?

Otherwise known as “climate engineering,” geoengineering refers to human manipulation of the planet’s climate system as a preventive measure to counteract global warming. Climate scientists predict that the effects of global warming could be disastrous. How far would we go to stave off catastrophe? Some researchers, backed by Bill Gates, Richard Branson, and other billionaires, have proposed the injection of sulfate aerosols into the stratosphere to manage solar radiation – creating a global dimming effect. Such a solution is dramatized by the movie Snowpiercer, in which the process plunges Earth into a new ice age. Critics of climate engineering argue that it could have unpredictable consequences – and create irreversible side effects.

In the fictional future depicted by Interstellar, a devastating blight has afflicted crops, resulting in widespread food shortages. But according to the UN, we are heading toward a global food crisis even without such a calamity. By the year 2030, we’ll need 50% more food and 30% more water. A 2012 UN report warned that current development models are unsustainable and that only a drastic reduction of the consumption of animal products could change our course. Of course, the hardest hit will be those in developing countries, and the approximately 800 million people already suffering chronic undernourishment.

Since the 1970s, the planet’s population has more than doubled, reaching a staggering 7.5 billion in 2017. How many people can the Earth sustain? The answer depends on a range of factors, but the median estimate is around 10 billion. If everyone consumed as much as the average American, this would reduce to about 2.5 billion. Such figures led the late Australian scientist Frank Fenner to predict that humans will be extinct within the next 100 years. He drew a parallel to what happened on Easter Island, where overcrowding resulted in conflicts over resources that weakened the population, after which Europeans all but finished them off. Similarly, we may one day surpass the planet’s carrying capacity.

On dry days, Beijing is shrouded in dense smog. Between 2004 and 2014 the incidence of lung cancer almost doubled. If we continue to burn fossil fuels at current rates, what will happen to the air we breathe? Does the dark cloud over Beijing foreshadow the fate of other industrialized cities around the world? In 2014, the World Health Organization estimated that air pollution caused the deaths of seven million people in 2012 alone. Air pollution is linked to heart disease, lung cancer, and respiratory infections, particularly in children in developing countries. And it isn’t just that we might poison ourselves – air pollution contributes to global warming and extinctions, endangering local and global ecosystems.

In the fourteenth century, the Black Death killed some 75-200 million people in Eurasia. Engineered diseases, designed deliberately for mass destruction, could prove even more devastating than past pandemics. Biological weapons can easily get out of control. Although the Geneva Protocol of 1925 banned their use, this didn’t stop the Japanese from testing them on prisoners and bombing China with plague-carrying fleas during World War II. Nor did it prevent the UK and US from weaponizing anthrax and other bio-agents. Producing biological weapons has been outlawed since 1972, but in 2011 researchers engineered an airborne strain of avian influenza, raising fears that a manmade pandemic could also be triggered accidentally.

The movie The Day After Tomorrow shows climate change as a sudden, immediate global catastrophe, with superstorms freezing half the planet solid within days. In reality, global warming is predicted to raise temperatures by just a few degrees over the course of decades. However, this alone is projected to mess with the weather, threaten fragile ecosystems, and raise sea levels high enough to inundate many coastal areas, potentially causing a massive refugee crisis. 97% of climate studies claim that the planet is warming due to human activity. To be fair, fossil fuel companies disagree. Meanwhile, governments have struggled to agree on specific actions, timetables, or measures of enforcement. But if scientific consensus is right, we’re already in trouble.

After witnessing the dark mushroom cloud of the first atomic bomb, its creator J. Robert Oppenheimer remarked: “Now I am become Death, the destroyer of worlds.” Fortunately, the number of nukes in the world has fallen from 70,000 in 1986 to around 15,000. But scientists recently concluded that even a regional nuclear conflict could have devastating consequences, blocking the sun with soot and ripping holes in the ozone layer. In 2017, scientists moved the Doomsday Clock, symbolic of our proximity to global catastrophe, forward to two and a half minutes to midnight. Can we pull back from the brink?

The idea of robots turning on their makers is a popular trope in science fiction. But a number of leading scientists, tech moguls, and philosophers fear that these dramatizations could also be prophetic. In 2014, Stephen Hawking warned that artificial intelligence could spell the end of the human race. Even Elon Musk, whose businesses are reliant on technological innovation, characterizes AI as our greatest existential threat. The fear is that once Artificial Intelligence learns to self-improve, it could lead to a runaway reaction where machines quickly supersede us. What happens when machines can outthink us? Watch out: Skynet could be just around the corner.