Robots taking over
Hans Moravec is a research professor at Carnegie Mellon University's Robotics Institute in Pittsburgh:
"Robot controllers double in complexity (processing power) every year or two. They are now barely at the lower range of vertebrate complexity, but should catch up with us within a half-century. By 2050 I predict that there will be robots with humanlike mental power, with the ability to abstract and generalise.
"These intelligent machines will grow from us, learn our skills, share our goals and values, and can be viewed as children of our minds. Not only will these robots look after us in the home, but they will also carry out complex tasks that currently require human input, such as diagnosing illness and recommending a therapy or cure. They will be our heirs and will offer us the best chance we'll ever get for immortality by uploading ourselves into advanced robots."
Chance of super-intelligent robots in the next 70 years: High
Danger score: 8
Professor Bill McGuire is director of the Benfield Hazard Research Centre at University College London and a member of Tony Blair's Natural Hazards working group:
"Approximately every 50,000 years the Earth experiences a super-volcano. More than 1,000 sq km of land can be obliterated by pyroclastic ash flows, the surrounding continent is coated in ash and sulphur gases are injected into the atmosphere, making a thin veil of sulphuric acid all around the globe and reflecting back sunlight for years to come. Daytime becomes no brighter than a moonlit night.
"The global damage from a super-volcano depends on where it is and how long the gas stays in the atmosphere. Taupo in New Zealand was the most recent super-volcano, around 26,500 years ago. However, the most damaging super-volcano in human history was Toba, on Sumatra, Indonesia, 74,000 years ago. Because it was fairly close to the equator it injected gas quickly into both hemispheres. Ice core data shows that temperatures were dramatically reduced for five to six years afterwards, with freezing conditions right down to the tropics.
"A super-volcano is 12 times more likely than a large meteorite impact. There is a 0.15% probability that one will happen in your lifetime. Places to watch now are those that have erupted in the past, such as Yellowstone in the US and Toba. But, even more worryingly, a super-volcano could also burst out from somewhere that has never erupted before, such as under the Amazon rainforest."
Chance of a super-volcano in the next 70 years: Very high
Danger score: 7
Hopefully the Robots will take over first, become benign dictators and politely adjust our respiratory, digestive and immune systems and save us from the volcano.
Or the volcano happens first and wipes out us and the robots, in which case at least the smug robots get a pasting too.