Global Risk: A Quantitative Analysis

Thomas McCabeRensselaer Polytechnic Institute

pphysics141@gmail.commccabt3@rpi.edu

Nuclear war A full-scale nuclear war in 1988, during the

height of the Cold War, could be expected to kill around 1,850,000,000 people, or 36% of the world's population.

Source: ”The Effects of a Global Thermonuclear War”, by Robert Johnston

Nuclear war WWII Holocaust Iraq war Bhopal 9/110

200000000

400000000

600000000

800000000

1000000000

1200000000

1400000000

1600000000

1800000000

2000000000

Casualties

Nuclear war WWII Holocaust Iraq war Bhopal 9/110

1

2

3

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5

6

7

8

9

10

Casualties (order of magnitude)

Smallpox epidemic In spite of vaccinations, smallpox killed 300

to 500 million people from 1900 through 1980.

A new smallpox epidemic today could kill up to two billion, or 30% of the population.

Sources: ”Smallpox: The Fight to Eradicate a Global Scourge”, by David Koplow

”The Nightmare of Bioterrorism”, by Laurie Garrett

Asteroid strike An asteroid two kilometers across hitting

Earth would cause massive tsunamis, fires, etc., and would kill around one to two billion people.

Such a strike occurs, on average, once every million years.

Source: Tsunami from Asteroid/Comet Impacts, by Michael Paine

Extinction risks Genetically engineered supervirus Global climate runaway feedback loop Nearby gamma ray burst Nearby supernova Environmental collapse Simulation gets shut down Rogue artificial intelligence Molecular nanotechnology accident Particle accelerator accident

Risk priority equation

P = I * L * R / E

P = risk priority I = impact of the risk L = likelihood of the risk R = how much the risk is reduced E = effort to reduce the risk

Priority of car crashes Impact: $100,000 Likelihood: 10% = 0.1 Risk reduction: 50% = 0.5 Effort = 10 hrs.

Risk priority = 100,000 * 0.1 * 0.5 / 10

= 500 $/hr.

Laplace's rule of succession Given a uniform prior distribution over

probabilities, if something has not happened during each of N independent tests, the probability that it will happen during the next test is 1 / (N + 2).

GRB probability There are 100 billion galaxies, and GRBs

happen around a hundred times a year, so the chances of one happening in our galaxy this year is around one in a billion.

Source: Deadly astronomical event not likely to happen in our galaxy, study finds, press release by Oregon State University

GRB probability If a GRB does happen in our galaxy, it would

have to be within three thousand light years to cause serious damage.

The galaxy is around a hundred thousand light years across, so the odds of this are roughly 1:250, for a combined probability of 1:250,000,000,000.

Inductive GRB probability We know that all life hasn't been killed by a

GRB in the past four billion years, so by Laplace's rule, the odds of us being killed next year are 1 / (4,000,000,000 + 2), or 1:4,000,000,002.

Nuclear war probability Martin Hellman's rough estimate: 1% per

year, or around 10% per decade.

Inductive estimate: 1 / (59 + 2) = 1:61, or around 1.6%.

Source: Risk Analysis of Nuclear Deterrence, by Martin Hellman

Chance of smallpox outbreak To my knowledge, no studies have been

done on this.

Inductive probability: 1 / (29 + 2) = 1:31, or around 3.2% per year.

Asteroid impact frequency

Risk mitigation Even if two risks have the same impact and

probability, one may be much easier to prevent.

Technological risks are always easiest to prevent when they are new, and the technology is still being developed.

Molecular nanotechnology

Molecular nanotechnology Ability to manufacture large numbers of

weapons at minimal cost, and destroy or conquer the world.

An MNT accident may wind up consuming the entire planet, including us, in a search for more raw materials.

Orders of magnitude

Comparison of relative risk

List of dangerous machines Lawnmower

Boeing 747 passenger jet

List of dangerous machines Lawnmower

Boeing 747 passenger jet

Quartz wristwatch

Saturn V rocket

Availability heuristic People tend to judge how dangerous things

are by how often they hear about them, either personally or through the media.

Popular estimates of causes of death are highly correlated with selective newspaper reporting.

Source: Newspaper coverage of causes of death, by Barbara Combs and Paul Slovic

Number of Google News hits Grey goo nanotechnology: 527 ”Asteroid impact”: 1,690 LHC destroy world: 7,880 Smallpox outbreak: 9,940 Anna Nicole Smith: 66,600 ”Nuclear war”: 84,700