Envisioning a world immune to global catastrophic biological risks

The COVID-19 pandemic has highlighted the continuing vulnerability of our civilization to serious harm from novel diseases, but it has also highlighted that our civilization's wealth and technology offer unprecedented ability to contain pandemics.  Logical extrapolation of DNA/RNA sequencing technology, physical barriers and sterilization, and robotics point the way to a world in which any new natural pandemic or use of biological weapons can be immediately contained, at increasingly affordable prices.  These measures are agnostic as to the nature of pathogens, low in dual use issues, and can be fully established in advance, and so would seem to mark an end to any risk period for global catastrophic biological risks (GCBRs).  An attainable defense-dominant 'win condition' for GCBRs means that we should think about GCBRs more in terms of a possible 'time of perils' and not an indefinite risk that sets a short life expectancy for our civilization.

What do historical statistics teach us about the accidental release of pandemic bioweapons?

Historically research on dangerous pathogens, for biodefense and bioweapons, has resulted in disturbingly frequent accidental infections of workers and sometimes escaping to the outside world.  Straightforward extrapolation of those accident rates suggests that large scale illegal programs working with bioweapons capable of posing global catastrophic biological risks (GCBRs) would be released into the world within a few decades.  However, if accidental release rates were so high, then why haven't there historically been more pandemics stemming from such releases?  Examining the known biological weapons programs, especially the Soviet program (by far the largest), we see that they were overwhelmingly working with diseases that were not capable of pandemic spread, with the few exceptions (particularly smallpox) subject to vaccination or having low fatality rates.  This should be expected: clearly the human population could not sustain many high fatality pandemic pathogens naturally circulating.  However, it appears that the Soviet program was engaged in active research to produce deadly pandemic pathogens, although it failed to do so with 1980s biotechnology.  If a future illegal bioweapons program were follow the Soviet example but succeed with more advanced biotechnology, historical rates of accidental release could pose a more likely threat than intentional use of the pandemic agents in warfare. 

Nuclear winter and human extinction: Q&A with Luke Oman

Cross-posted from Overcoming Bias

In Reasons and Persons, philosopher Derek Parfit wrote:

I believe that if we destroy mankind, as we now can, this outcome will be much worse than most people think. Compare three outcomes: 

1. Peace
2. A nuclear war that kills 99% of the world's existing population.
3. A nuclear war that kills 100% 

2 would be worse than 1, and 3 would be worse than 2. Which is the greater of these two differences? Most people believe that the greater difference is between 1 and 2. I believe that the difference between 2 and 3 is very much greater... If we do not destroy mankind, these thousand years may be only a tiny fraction of the whole of civilized human history.

The ethical questions raised by the example have been much discussed, but almost nothing has been written on the empirical question: given nuclear war, how likely is scenario 3?

The most obvious path from nuclear war to human extinction is nuclear winter: past posts on Overcoming Bias have bemoaned neglect of nuclear winter, and high-lighted recent research. Particularly important is a 2007 paper by Alan Robock, Luke Oman, and Georgiy Stenchikov:  "Nuclear winter revisited with a modern climate model and current nuclear arsenals: Still catastrophic consequences." Their model shows severe falls in temperature and insolation that would devastate agriculture and humanity's food supply, with the potential for billions of deaths from famine in addition to the direct damage.

So I asked Luke Oman for his estimate of the risk that nuclear winter would cause human extinction, in addition to its other terrible effects. He gave the following estimate:

The probability I would estimate for the global human population of zero resulting from the 150 Tg of black carbon scenario in our 2007 paper would be in the range of 1 in 10,000 to 1 in 100,000.
I tried to base this estimate on the closest rapid climate change impact analog that I know of, the Toba supervolcanic eruption approximately 70,000 years ago.  There is some suggestion that around the time of Toba there was a population bottleneck in which the global population was severely reduced.  Climate anomalies could be similar in magnitude and duration.  Biggest population impacts would likely be Northern Hemisphere interior continental regions with relatively smaller impacts possible over Southern Hemisphere island nations like New Zealand.

Luke also graciously gave a short Q & A to clarify his reasoning, below the fold:

What to eat during impact winter?

A number of possible global catastrophic risks seem like they would do their worst damage by disrupting food production. Some examples include nuclear winter, asteroid impacts, and supervolcanoes. In addition to directly laying waste to significant areas, such events would cast ash, dust, or other materials into the atmosphere. Temperatures would fall and solar radiation for primary producers would be reduced, causing agricultural failures and wreaking havoc on wilderness ecologies. It seems clear that feasible events of this sort could cost hundreds of millions or even billions of lives. But would even extreme events actually bring about would they cause human extinction or constitute an existential risk?

There are several sources of evidence we can bring to bear on the question. We can apply the "outside view" and consider the species, including hominids and primates, that have survived past volcanic and asteroid impacts. We can examine current supplies of food sources that could provide for humans during a period of impaired solar radiation. And we can look at past and present social behavior that bears on the distribution of food and recovery from period of severe famine. In the aggregate, it seems to me that humanity would survive one of these severe food disruptions, despite terrible quantities of death and misery.

This post will take a first-pass look at existing food sources that could be drawn upon during a "year without the Sun," or something close to it.