Bostrom, Nick & Milan Ćirković (eds.) (2008) Global Catastrophic Risks, Oxford: Oxford University Press.
A global catastrophic risk (GCR) is an event that poses a risk of major harm on a global scale.[1]
GCRs risks include, but are not restricted to, existential risks. Examples of non-existential GCRs include risks of hundreds of millions of people dying due to a natural pandemic or due to anthropogenic climate change.
(Source: EA Forum wiki entry)