Seven possible doomsday scenarios
An asteroid striking Earth is a possibility, but we’re more likely to destroy ourselves
Our solar system is littered with billions of pieces of debris, from the size of large boulders to objects hundreds of miles across. We know that from time to time these hit Earth. Now, a Russian scientist has calculated that a mountain-sized asteroid — which crosses paths with the Earth every three years — could one day hit us with an explosion 1,000 times greater than the surprise 2013 impact of a bus-sized meteor in Russia.
This is not the only doomsday scenario faced by our planet. Humanity may have already created its own nemesis, according to Prof. Stephen Hawking. The Cambridge University physicist claimed that new developments in the field of artificial intelligence (AI) mean that, within a few decades, computers thousands of times more powerful than in existence today may decide to usurp their creators and end humanity’s 100,000year dominance of Earth.
This ‘Terminator’ scenario is taken seriously by many scientists and technologists. Before Hawking made his remarks, Elon Musk, the genius behind the Tesla electric car and PayPal, stated that “with artificial intelligence, we are summoning the demon.”
Aside from the rise of the machines, many potential threats have been identified to our species, our civilization or even our planet itself. Here are seven of the most plausible.
1. Asteroid strike
Sixty-five million years ago, an object, possibly a comet a few times larger than the one landed on by the Philae probe last month, hit the Mexican coast and triggered a global winter that wiped out the dinosaurs. And in 1908, a smaller object hit a remote part of Siberia and devastated hundreds of square miles of forest.
Probability: Remote in our lifetime, but one day we will be hit.
Result: There has been no strike big enough to wipe out all life on Earth for at least three billion years. But a dino-killer would certainly be the end of our civilization and possibly our species.
2. Artificial intelligence
Hawking is not worried about armies of autonomous drones taking over the world, but something more subtle — and more sinister. Some technologists believe that an event they call The Singularity is only a few decades away. This is a point at which the combined networked computing power of the world’s AI systems begins a massive, runaway increase in capability — an explosion in machine intelligence. By then, we will probably have handed over control to most of our vital systems, from food distribution networks to power plants, sewage and water treatment works and the global banking system. The machines could bring us to our knees without a shot being fired.
Probability: Unknown — although computing power is doubling every 18 months. We do not know if machines can “want” to do anything.
Result: If the Web wakes up and wants to sweep us aside, we may have a fight on our hands. But it is unlikely that the machines will want to destroy the planet — they live here, too.
3. A genetically created plague
Possibly the most terrifying short-term threat — because it is so plausible. The reason Ebola has not become a worldwide plague — and will not do so — is because it is so hard to transmit, and because it incapacitates and kills its victims so quickly. However, a modified version of the disease that can be transmitted through the air, or which allows its host to travel around for weeks, symptom-free, could kill many millions. It is unknown whether any terror group has the knowledge or facilities to do something like this, but it is chilling to realize that the main reason we understand Ebola so well is that its potential to be weaponized was quickly realized by defence experts.
Probability: Someone will probably try it one day.
Result: Potentially catastrophic. “Ordinary” infectious diseases such as avian flu strains have the capability to wipe out hundreds of millions.
4. Nuclear war
Still the most plausible doomsday scenario. Despite arms limitations treaties, there are more than 15,000 nuclear warheads and bombs in existence — enough, in theory, to kill every human on Earth several times over. Even a small nuclear war has the potential to cause widespread devastation.
Probability: High. Nine states have nuclear weapons, and more want to join the nuclear club.
Result: It is unlikely that even a global nuclear war between Russia and NATO would wipe us all out, but it would kill billions and wreck the world economy for a century.
5. Particle accelerator disaster
Before the Large Hadron Collider, the massive machine at CERN in Switzerland that detected the Higgs Boson a couple of years ago, was switched on, there was a legal challenge from a German scientist called Otto Rossler who claimed the atom-smasher could theoretically create a small black hole by mistake — which would then go on to eat the Earth.
The claim was absurd: the collisions in the LHC are far less energetic than the natural collisions caused by impacting cosmic rays hitting the planet. But it is possible that, one day, a souped-up version of the LHC could create something that destroys the planet — or even the universe — at the speed of light. Probability: Very low. Result: Potentially devastating, but don’t bother cancelling the house insurance just yet.
6. ‘God’ reaches for the off-switch
Many scientists have pointed out that there is something fishy about our universe. The physical constants — the numbers governing the fundamental forces and masses of nature — seem fine-tuned to allow life of some form to exist.
Oxford University philosopher Nick Bostrom has speculated that our universe may be one of countless “simulations” running in some alien computer, much like a computer game. If so, we have to hope that the beings behind our fake universe are benign — and do not reach for the off-button should we start misbehaving.
Probability: According to Bostrom’s calculations, if certain assumptions are made, then there is a greater than 50 per cent chance that our universe is not real. And the puzzling absence of any evidence of alien life may be indirect evidence that the universe is not what it seems.
Result: Catastrophic — if the gamers turn against us.
7. Climate catastrophe
Almost no serious scientists now doubt that human carbon emissions are having an effect on the planet’s climate. The latest report by the Intergovernmental Panel on Climate Change suggested that containing temperature rises to below 2 C above the pre-industrial average is now unlikely, and that we face a future 3 or 4 degrees warmer than today.
This will not literally be the end of the world — but humanity will need all the resources at its disposal to cope with such a dramatic shift. Millions face losing their homes to sea-level rises (by up to a metre or more by 2100) and shifting weather patterns may disrupt agriculture dramatically.
Probability: It is now almost certain that CO2 levels will keep rising to 600 parts per million and beyond. And it is equally certain that the climate will respond accordingly.
Result: Catastrophic in some places, less so in others (including northern Europe, where temperature rises will be moderated by the Atlantic). The good news is that we have a chance to do something about climate change now.