A global catastrophic risk (GCR) is an event that poses a risk of major harm on a global scale (Bostrom & Ćirković 2008).
GCRs risks include existential risks, but are not restricted to them. Examples of non-existential global catastrophic risks include risks of hundreds of millions (but not billions) of people dying due to a natural pandemic or due to climate change.
Such catastrophic risks have obviously bad direct effects: they may involve many people dying, or our technological capabilities being greatly reduced. There may also be bad indirect effects, for instance by destabilizing political systems in a way that increases the likelihood of war or totalitarian government.
Some think that these indirect effects of catastrophic risks might result in existential risks. For instance, climate change might increase political tensions, hastening nuclear or biological warfare. Others think it’s more likely that civilization will eventually rebound to something like it’s previous state. Both the Black Death and the Plague of Justinian killed something like 15% of the world’s population without obviously derailing humanity’s long-term potential.
Even if global catastrophic risks do not pose an existential risk, they might still be high priority causes justified purely by their nearer-term consequences.
Aird, Michael (2020) Collection of some definitions of global catastrophic risks (GCRs), Effective Altruism Forum, February 28.
Many additional resources on this topic.
Avin, Shahar et al. (2018) Classifying global catastrophic risks, Futures, vol. 102, pp. 20–26.
Beckstead, Nick (2015) The long-term significance of reducing global catastrophic risks, Open Philanthropy, August 13.
A blog post investigating the extent to which global catastrophic risks might have long-term or potentially existential consequences.
Berger, Alexander (2014) Potential global catastrophic risk focus areas, Open Philanthropy, June 26.
Bostrom, Nick & Milan Ćirković (2008) Global Catastrophic Risks, Oxford: Oxford University Press.
Cotton-Barratt, Owen et al. (2016) Global catastrophic risks 2016, Global Challenges Foundation/Global Priorities Project.
A report examining various types of global catastrophic risk.
Open Philanthropy (2014) Global catastrophic risks, Open Philanthropy, February .
An investigation into the importance of global catastrophic risks.
Kemp, Luke & Catherine Rhodes (2020) The cartography of global catastrophic governance, Cambridge: Centre for the Study of Existential Risk.
Koehler, Arden & Keiran Harris (2020) Owen Cotton-Barratt on epistemic systems & layers of defence against potential global catastrophes, 80,000 Hours, December 16.