Intelligent computers that take over the world and an incurable virus that kills off the human race might sound like plots worthy of a Hollywood blockbuster - but scientists insist they are real threats.
They are just two of the 12 ways the world could end, according to new research.
A team from Oxford University's Future of Humanity Institute and the Global Challenges Foundation has come up with the first serious scientific assessment of the apocalyptic risks we face.
A few of the scenarios arise from events that are out of our control - such as an asteroid hitting the Earth or the eruption of a supervolcano - but most emerge from human advancements.
Some of these developments, particularly those that are technological, have the potential to bring great benefits humans - but could also lead to our demise.
The report states: 'This is a scientific assessment about the possibility of oblivion, certainly, but even more it is a call for action based on the assumption that humanity is able to rise to challenges and turn them into opportunities.'
An apocalyptic disease would be incurable (like Ebola), nearly always fatal (like rabies), extremely infectious (like the common cold) and have long incubation periods (like HIV).
If these devastating features were to occur in a single pathogen - influenza is already capable of combining features from different viruses - then the death toll would be extreme.
While significant resources have been dedicated to medical research and combating disease, modern transport and dense populations allow infections to spread quickly.
The danger of a supervolcano - one capable of producing an eruption 1,000 times larger than normal - is the amount of aerosols and dust sent into the atmosphere.
This dust would absorb the Sun's rays and cause a global 'volcanic winter' - with effects similar to those of an asteroid impact or a nuclear war.
With technology currently available, there is little that could be done to prevent the damage.
Perhaps the most-discussed apocalyptic threat of the moment, this refers to the development of machines and software with human-level intelligence.
Such intelligences could not be easily controlled - either by the groups creating them, or some international body - and would probably be able to boost their own intelligence.
And if they decide humanity if of no value, they will be driven to build a world without humans.
But such artificial intelligence could easily combat most other risks in the report - making it a tool of great potential.
At the moment, no one knows whether there is a real risk of extreme machine intelligence and the researchers therefore give it a wide estimate of probability.
Extreme climate change
Scientists currently predict climate change caused by human activity - adding carbon dioxide to the atmosphere - could mean average global temperatures increase by 4C.
But there is a risk that the warming could be much more extreme than the estimates suggest - and rise up to 6C.
The impact would be strongest in poorer countries, which would become uninhabitable, the research concludes, and lead to mass deaths, famines and mass migration.
Genetic engineering of super-organisms could be beneficial for humanity. But the release of a super-organism that targets humans, or a crucial part of the ecosystem, could end in disaster.
This could either be leaked accidentally - unintentionally from a laboratory - or deliberately - in instances of bio-warfare or bio-terrorism.
The impact could be worse than any natural pandemic.
Currently, attempts at regulation or self-regulation are in their infancy, and may not develop as fast as research does.
It might sound like the stuff of science-fiction - but a major asteroid impact could lead to the end of the world.
Large asteroid collisions - with objects 5 km or more in size - happen about once every 20 million years and would have an energy a 100,000 times greater than the largest bomb ever detonated.
A land impact would destroy an area the size of a nation like the Netherlands.
Should an asteroid hit, destruction would be caused by the clouds of dust shot into the atmosphere - affecting climate, food supplies and creating political instability - rather than the initial impact.
A complete breakdown of the global ecosystem - often leading to mass extinction.
The likelihood of this depends on the extent to which humans are dependent on the ecosystem. Some lifestyles, for example, could be sustained if they were independent from the network.
Whether this can be achieved on a large scale in practice, especially during a collapse, will be a technological challenge, and whether it is something that is wanted, is an ethical question.
Super-precise manufacturing on an atomic level could create materials with new properties - such as being highly resilient or 'smart' - that would be highly beneficial.
These manufacturing technologies could offer some of the world's biggest problems - including the depletion of natural resources, pollution, climate change, clean water and even poverty.
But it could also lead to the creation of large arsenals of conventional or more novel weapons made possible by atomically precise manufacturing.
The fear of an apocalyptic nuclear war between Russia and the US gripped the global community for decades.
That threat may have reduced, but the potential for deliberate or accidental nuclear conflict has not been reduced, with some estimates putting the risk in the next century at around 10 per cent.
Whether the war has a larger impact would depend on whether it triggered a 'nuclear winter' - the creation of a cloud of smoke high in the atmosphere that would block the Sun's rays, plunging temperatures below freezing, and possibly destroy the ozone layer.
In order for this to happen, the bombs would have to start massive firebombs that could lift the dust into the atmosphere.
The effects would lead to the disintegration of the global food supply - making widespread starvation and the collapse of states likely.
Bad local governance
This refers to two main categories of government disasters - failing to solve major solvable problems and actively causing worse outcomes.
An example of the first would be failing to alleviate absolute poverty; of the second, constructing a global totalitarian state.
Changes in technology, politics and society could lead to the creation of better governments, but it could also give us those that are much worse.
Global system collapse
This broad term refers to an economic or societal collapse on a global scale that involves civil unrest and a breakdown of law and order that makes the continuation of human life impossible on Earth.
There are too many unknown factors to predict how likely this outcome would be but such effects have been observed in intricately-connected systems like ecology and finance.
The possibility of collapse is more acute when several networks depend on each other.
An umbrella category that represents all of the unknown unknowns - risks we have not thought about or appear extremely unlikely in isolation.
Together they recommend a significant apocalyptic threat.
- Daily Mail