Aftermath of Global Catastrophes Project

PROJECT LEADS: Seth Baum and Dave Denkenberger

A few global catastrophes could kill everyone right away. For these GCRs, there is no significant aftermath to speak of. However, for the rest of the GCRs, what happens in the aftermath is extremely important. At stake is no less than the long-term success of human civilization. Yet there has been extremely little prior work on the aftermath of global catastrophes. Perhaps the topic has been avoided because it is highly uncertain, or because it is so grim. Regardless, GCRI is beginning to fill this large, dark void.

The Importance Of The Aftermath

Early research on GCR argued that catastrophes resulting in human extinction would be much worse than catastrophes resulting in even as much as a 99% decline in world human population [1]. This research argued that extinction is permanent, but even a small survivor population could rebuild civilization, with insignificant long-term harm. Contemporary scholarship recognizes that any catastrophe causing significant permanent harm is comparably important to catastrophes resulting in human extinction. The contemporary scholarship began with Nick Bostrom’s work on existential risk [2]. GCRI has contributed to this scholarship through new research led by Associate Tim Maher and Executive Director Seth Baum. Maher and Baum developed the concepts of adaptation to and recovery from global catastrophe. If survivors successfully adapt to post-catastrophe conditions, then extinction will not occur. If survivors successfully recover, then the long-term harms will be small, though not necessarily insignificant [3]. The bottom line is that all GCRs for which rapid recovery is not guaranteed are of comparable importance. Focus should not be exclusively on GCRs resulting in immediate human extinction.

Reducing Uncertainty

What would happen to global catastrophe survivors? Would they adapt, avoiding extinction? Would they recover civilization? How rapidly? Answers to these questions are highly uncertain. Few studies have attempted to answer them. The study by GCRI’s Maher and Baum calls for dedicated research on this topic and offers some initial insights. Specifically, the study examines the environmental and social stressors that survivors might face [3]. For example, survivors of nuclear war will face environmental stressors related to nuclear winter, including colder temperatures, reduced sunlight and precipitation, and increased ultraviolet radiation. Survivors of many global catastrophes could face social stressors such as the breakdown of law and order and the onset of violent conflict. Other GCRI research has found that in some cases, the initial global catastrophe could cause a second one. For example, a pandemic or war could cause the failure of geoengineering, a risky emerging technology. The geoengineering failure would hit a population already vulnerable from the initial catastrophe, making for an especially harmful “double catastrophe” [4]. These studies show some of the ways that the aftermath of global catastrophes could occur, and likewise some of the ways that the uncertainty about the aftermath can be reduced.

Helping Survivors Succeed

Another reason it is important understand the aftermath of global catastrophes is to develop interventions that could help survivors adapt to and recover from post-catastrophe conditions [5]. GCRI researchers have worked on several such interventions. Space colonies could ensure that some humans survive catastrophes that destroy Earth, and could “piggyback” on other space missions [6]. Refuges on Earth may be a more cost-effective option for many global catastrophe scenarios [6]. However, the general cost-effectiveness of refuges has been questioned [7]. Stockpiles of food and other critical resources may be even more cost-effective [3]. But even stockpiles can be expensive [8]. In response to this issue, GCRI Associate Dave Denkenberger and Joshua Pearce of Michigan Technological University developed a new proposal for “alternative food”. This food is “alternative” because it is grown not by sunlight, but by other energy sources. One energy source is stored biomass from trees and other plants that remain after the catastrophe. Another energy source is fossil fuel, in particular natural gas. From these energy sources, a range of familiar and exotic foods can be grown, including mushrooms, chickens, and edible “bacterial slime” [8, 9]. The alternative foods work has attracted some popular media attention, especially for the part about bacterial slime. Innovative proposals like this promise to help survivors succeed and improve the long-term prospects for human civilization.


[1] Carl Sagan, 1983. Nuclear war and climatic catastrophe: Some policy implications. Foreign Affairs 62, 257-292. Derek Parfit, 1984. Reasons and Persons. Oxford: Oxford University Press.

[2] Nick Bostrom, 2002. Existential risks: Analyzing human extinction scenarios and
related hazards
. Journal of Evolution and Technology 9. Nick Bostrom, 2013. Existential risk prevention as a global priority. Global Policy 4(1), 15-31. An excellent treatment of this topic is found in Nicholas Beckstead, 2013. On The Overwhelming Importance Of Shaping The Far Future. Doctoral Dissertation, Department of Philosophy, Rutgers University.

[3] Timothy M. Maher, Jr. and Seth D. Baum, 2013. Adaptation to and recovery from global catastrophe. Sustainability 5(4), 1461-1479.

[4] Seth D. Baum, Timothy M. Maher, Jr., and Jacob Haqq-Misra, 2013. Double catastrophe: Intermittent stratospheric geoengineering induced by societal collapse. Environment, Systems and Decisions 33(1), 168-180.

[5] For a broad discussion of this topic, see Lewis Dartnell, 2014. The Knowledge: How to Rebuild Civilization in the Aftermath of a Cataclysm. New York: Penguin.

[6] Seth D. Baum, 2009. Cost-benefit analysis of space exploration: Some ethical considerations. Space Policy 25(2), 75-80. Seth D. Baum, David C. Denkenberger, and Jacob Haqq-Misra. Isolated refuges for surviving global catastrophes. Futures, 72, 45-56. See also Karim Jebari, 2015. Existential risks: Exploring a robust risk reduction strategy. Science and Engineering Ethics, 21(3), 541-554.

[7] Nick Beckstead, 2015. How much could refuges help us recover from a global catastrophe? Futures, 72, 36-44.

[8] Seth D. Baum, David C. Denkenberger, Joshua M. Pearce, Alan Robock, and Richelle Winkler. Resilience to global food supply catastrophes. Environment, Systems, and Decisions, 35(2), 301-313.

[9] David Denkenberger and Joshua Pearce, 2014. Feeding Everyone No Matter What: Managing Food Security After Global Catastrophe. Waltham, MA: Academic Press. David C. Denkenberger and Joshua M. Pearce. Feeding everyone: Solving the food crisis in event of global catastrophes that kill crops or obscure the sun. Futures, 72, 57-68. David C. Denkenberger and Joshua M. Pearce. Cost-effectiveness of interventions for alternate food to address agricultural catastrophes globally. International Journal of Disaster Risk Science, forthcoming, DOI 10.1007/s13753-016-0097-2.