International researchers commissioned by a Swedish foundation to analyse global risks have come up with a list of 12 doomsday scenarios facing humankind. While climate change tops the list, artificial intelligence is also regarded as a threat to our existence. André Anwar reports from Stockholm.

Climate change is the greatest threat to humankind, finds a study from researchers in Sweden and the United Kingdom. (Photo credit: NASA Goddard Space Flight Center)
Humankind and planet Earth will perish at some point. Of that there is little scientific doubt. But while much effort has gone into determining when this will happen, the prestigious Stockholm-based Global Challenges Foundation set itself a different challenge: to examine just what might precipitate humankind’s downfall.
The end is still far off
Researchers at the foundation and the Future of Humanity Institute at Oxford University identified twelve possible scenarios and divided them into several categories. Overall, the likelihood of events that would either severely decimate humanity or even lead to its outright extinction are highly unlikely for at least the next several centuries, the researchers point out. Nevertheless, the risks should be taken seriously given that at least some of them can be prevented.
While the risks are the stuff of headlines or Hollywood films, the real focus of their report is not on the risks themselves. Rather, the purpose of the report is “to encourage global collaboration and to use this new category of risk as a driver for innovation”, write the researchers.
Climate change is humankind’s greatest threat
The first five doomsday scenarios belong to the category of current risks. At the top of the list is extreme climate change. If temperatures increase by 4 degrees above pre-industrial levels, global warming would be strongest in poorer countries, many of which could become completely uninhabitable. Mass deaths, famine, social collapse and mass migration are all possible in this scenario, while food and resource shortages in developed countries could lead to global conflicts. Nuclear war came in second, followed by ecological catastrophe, such as when a species that the entire ecosystem depends on goes extinct. Global pandemic, such as an epidemic of infectious disease that spreads widely through human populations, came in fourth.
Global system collapse was identified as the fifth global risk that currently threatens human civilisation. The term is used to describe a broad range of conditions that leads to economic or societal collapse and that would decimate the population to the extent that it is threatened with extinction. All of these belong to the first category of self-induced threats that threaten humanity at present because of our economic and technological development.
Sun could scorch planet Earth
The second category of doomsday scenarios consists of external – or exogenic – risks that are beyond humankind’s control. These include a major asteroid impact or change to the structure of the planet, which came in sixth. In 2013 in the scientific journal Astrobiology, for example, scientists calculated that the Sun’s scorching heat will dry up planet Earth starting in around 1.75 billion years from now, which means that Earth is nearing the end of its lifespan. Or take an asteroid more than 5 kilometres in size that impacts on land: it would destroy an area the size of Holland and could unleash a chain reaction from clouds of dust projected into the upper atmosphere to deadly climate change. Fortunately, the likelihood of this occurring in the next 100 years is only 0.00013 per cent.
Super-volcanoes – which have much larger magma chambers than ordinary volcanoes and are capable of producing an eruption that is thousands of times larger than normal eruptions – captured seventh place. The danger from super-volcanoes is the extreme ash clouds would absorb the Sun’s rays and cause a global volcanic winter. The last super-volcano eruption occurred around 26,500 years ago in what is today New Zealand. Although such events are by their very nature beyond our control, the authors argue that the probability and magnitude of their impact could be influenced, for instance by developing technology to deflect an asteroid or by countries working together to mitigate the risk and damage from a super-volcano.
Artificial intelligence could kill us off
The next group consists of emerging risks to humankind’s survival. These include synthetic biology (eighth place) and nanotechnology (ninth). Artificial intelligence comes in tenth because it cannot be easily controlled (either by the groups creating them or a global regulatory regime) and it could even be driven to construct a world without humans. Uncertain risks or risks of unknown consequences came in eleventh.
The last of the 12 doomsday scenarios is future bad global governance, which exists all on its own in the category of global policy risks. Examples include failing to solve major solvable problems, such as poverty, and actively causing worse outcomes to current human challenges by constructing a global totalitarian state.