Will we be fighting off robots? Some of the world’s top scientists believe artificial intelligence could be the end of humanity. Source: News Corp Australia

If anyone else said this, we would laugh it off but Stephen Hawking and Elon Musk are two very intelligent men who most of the world takes seriously. Hawking, a world renowned physicist and Musk, the brains behind Tesla motors, PayPal and Space X, know a thing or two about science.

Well, it’s probably not going to be robot armies, but an event called “The Singularity”. This event, which some scientists believe is only decades away, will be when the combined network of the world’s computers and AI have an explosion of machine intelligence.

By then, most of our food distribution, banking and other vital systems will be conducted through that network. Which means the “explosion” of intelligence could bring us to our knees.

But what are some of the other threats to humanity and life as we know it? If the Terminator doesn’t do us all in, what’s the next most obvious option? We asked Dr Karl Kruszelnicki about some more plausible theories.

1. Climate change

Scientists, including Dr Karl, say you would have to be pretty daft to not acknowledge the effect that humans and our carbon emissions are having on the planet. Recent reports suggest that average temperatures will likely rise 2-4 degrees from where they are today, which will create a dramatic environmental shift.

The author of an Australian climate change report from earlier this year, Professor Will Steffen, has warned that the economic damage will be just as bad as the physical damage.

“We’re talking about the loss of beaches, property, infrastructure and commercial assets worth billions to our economy,” he said.

This probably won’t end humanity, but we will need to learn to focus all our resources on getting through it. Millions of mostly people - most of whom are poor - will lose their homes, and weather shifts will greatly change the agriculture industry.

Most scientists agree our climate is already changing, causing more storms, cyclones, floods and droughts. Picture: Jonathan Wood / Getty Images Source: Getty Images

2. Nuclear war

Movies and video games would certainly like you to believe that a nuclear war is the most plausible way for humanity to end.

While Dr Karl pointed out that we have gone from around 50,000 nuclear weapons across the world to about 16,000, he says even one nuke going off in a major city would have a catastrophic effect for the rest of the world.

While a war between Russia and Western countries probably won’t end absolutely everything, it would send us into a nuclear winter. Not just from the immediate damage or radiation - the Earth would get cooler, the ozone layer would be damaged and rainfall would be significantly reduced, meaning the crops we use for food would struggle to grow.

The effect of this would be felt for up to 20 years.

A nuclear bomb could cause more problems across the world than just in the location hit. Source: News Limited

3. The Carrington Event

What would happen if the sun decided to have a hissy fit? World chaos. Back in 1859, the sun threw a few billion tonnes of super-hot gases right at Earth. Its impact on our planet’s magnetic field was so huge that it destroyed 5% of the ozone and set off huge electric currents in the ground hitting telegraph lines.

Dr Karl believes a solar flare similar to the Carrington Event could be a major threat. Source: News Limited

But if that same event happened today, it would turn the earth into chaos says Dr Karl.

He says that “nearly 10% of the working satellites in orbit would stop working, costing $100 billion to fix. On top of that, banks rely on the time signals from GPS satellites, meaning they wouldn’t be able to give money.”

Electricity grids are also at risk, with something the size of the Carrington Event able to kill the entire North American electrical grid. And the phones and computers we all rely on so much would die from electrical spikes.

While storms like the Carrington Event hit every 500 years or so, events half as powerful hit every 50 years. The most recent being in 1960 which led to radio outages all over the world.

4. Asteroids

Could we be wiped out by asteroids? Do we need Bruce Willis to save us? Actually, probably yes. That is if we haven’t already destroyed the earth ourselves.

Back in June, an Asteroid over 300m big narrowly missed hitting Earth. But if it did make contact, Dr Karl said the effects would be catastrophic.

“If the asteroid landed in the Pacific Ocean, a 100m tsunami would require major evacuations in North America, South America, Asia, Russia and Australia,” he said.

There have been calls by famous astronomers and scientists for the creation of a global warning system to alert us if a giant killer rock is heading our way. As crazy as it sounds, such a system would give us enough time to fire rockets at it and alter its path to miss Earth.

An asteroid impact is probably the most likely of all, just not in our time. Source: ThinkStock

5. Zombies

Aside from a nuclear war, zombies are easily Hollywood’s favourite villain in ending humanity as we know it. Whether it be from a bad vaccine or a case of rabies, humans will become rabid and try to eat each other/turn each other into zombies. But the likelihood of this actually happening is zero to none.

Don’t worry, Simon Pegg won’t be in charge of saving humanity. Source: News Limited

But if we somehow manage to survive all of that, Dr Karl says that in one billion years, the Earth will be too hot for any life to live. And in five billion years, the sun will become a “red giant” and swallow Earth - and even Mars, in case you thought we could evacuate there.