Green Swan
Definition
Green Swan is a neologism based on the previously established Black Swan neologism.[1][2]
It is a framework of thinking about risks associated with the Biosphere, terming them ‘green swans’ (or environmental black swans) (Bank of International Settlements, 2020a).
Green swans present many features of typical black swans in that
- they are unexpected when they occur by most agents (who regard the past as a good proxy of the future);
- they feature non-linear propagation;
- impacts are significant in magnitude and intensity; and
- they entail large negative externalities at a global level
However, despite several common features, ‘black swans’ and ‘green swans’ differ in several key aspects. A key difference is their likelihood of occurrence. ‘Green swans’ are either likely or quite certain to occur (e.g. increased droughts, water stress, flooding, and heat waves), but their timing and form of occurrence are uncertain. By contrast, ‘black swans’ do not manifest themselves with high likelihood or quasi-certainty.
