You can now see an excellent visualization of global catastrophic risks estimates produced in the Ragnarök series here.

No single disease currently exists that combines the worst-case levels of transmissibility, lethality, resistance to therapies, and global reach. But we know that the worst-case attributes can be realized independently. For example, some diseases exhibit nearly a 100% case fatality ratio in the absence of treatment, such as rabies or septicemic plague. The 1918 flu has a track record of spreading to virtually every human community worldwide. Chickenpox and HSV-1, can reportedly reach over 95% of a given population.

The past decades have seen rapid advances in biotechnology, in part due to the falling costs of gene sequencing and synthesis. Improvements in ease-of-use of certain specific kinds of biotechnology bring increased concerns about biological risks. Gene synthesisers have the capacity to turn digital sequence data into physical genetic sequences, enabling individuals to create viruses from digital files (as was done with the 1918 Spanish Flu virus).

The implications of these technologies are worrying, especially given the track record of state-run bioweapon research applying cutting-edge science and technology to design pathogens that are more virulent, more resistant to therapies, harder to diagnose and treat than those in nature.

While there is no evidence of state-run bioweapons programs directly attempting to develop or deploy bioweapons that would pose an catastrophic risk, the logic of deterrence and mutually assured destruction could create such incentives, especially in a more unstable political climate, or following a breakdown of the Biological Weapons Convention.

Deliberate or accidental gene drives that might not directly target human populations may also pose major risks. There are broadly three features that give rise to the ecological risk of gene drives:

(i) a gene drive is passed on from one generation to the next at a rate greater than occurs naturally; (ii) a gene drive construct can have effects on other parts of the organism's genome beyond the target; and (iii) gene-drive modified organisms are designed to spread, along with their effects, into the larger environment.

Examples of such unanticipated consequences that could rapidly proliferate the ecosystem are:

• New phenotypes with a different (possibly increased) capacity to spread diseases or pathogens,
• Cascading effects on food web caused by decrease in abundance of predators leading to possible loss of ecosystem services,
• The gene drive being acquired by, and spreads within, non-target species (possibly humans), leading to suppression or modification of the nontarget species.

Finally, accidents. A report by Gryphon Scientific, Risk and Benefit Analysis of Gain of Function Research, has laid out a detailed risk assessments of potentially pandemic pathogen research, suggesting that the annual probability of a global pandemic resulting from an accident with this type of research in the United States is 0.002% to 0.1%. Since similar research is done outside of the United States, in potentially more accident-prone labs, the world seems to be exposed to worryingly high level of risk from accidental outbreaks (which some have estimated to be around 0.016% to 0.8% chance of a pandemic each year).

In the headline question to this series, we defined a global catastrophe as a 10% decrease in the world population in any period of 5 years.

If a global catastrophe happens before 2100, will it be principally due to the deployment biotechnologies or bioengineered organisms?

The question resolves positively if a global biotechnology catastrophe occurs resulting from the deployment biotechnologies or bioengineered organisms (including viruses) that claims at least 10% in any period of 5 years or less before 2100, and resolves as ambiguous if no global catastrophe occurs. Bioengineering is here defined to include the application of biotechnology to enhance or increase the virulenc, infectiousness or resistance to treatment of naturally ocurring viruses.

If the failure-mode is less direct, such as through indirect ecological effects of gene drives, the catastrophe must be generally believed very unlikely in a counterfactual world with little or no biotechnological interventions but otherwise similar to ours. Years are here defined as consecutive calendar years.