Table 1.

Defining key terms in the Climate Endgame agenda

Term	Definition
Latent risk	Risk that is dormant under one set of conditions but becomes active under another set of conditions.
Risk cascade	Chains of risk occurring when an adverse impact triggers a set of linked risks (3).
Systemic risk	The potential for individual disruptions or failures to cascade into a system-wide failure.
Extreme climate change	Mean global surface temperature rise of 3 °C or more above preindustrial levels by 2100.
Extinction risk	The probability of human extinction within a given timeframe.
Extinction threat	A plausible and significant contributor to total extinction risk.
Societal fragility	The potential for smaller damages to spiral into global catastrophic or extinction risk due to societal vulnerabilities, risk cascades, and maladaptive responses.
Societal collapse	Significant sociopolitical fragmentation and/or state failure along with the relatively rapid, enduring, and significant loss capital, and systems identity; this can lead to large-scale increases in mortality and morbidity.
Global catastrophic risk	The probability of a loss of 25% of the global population and the severe disruption of global critical systems (such as food) within a given timeframe (years or decades).
Global catastrophic threat	A plausible and significant contributor to global catastrophic risk; the potential for climate change to be a global catastrophic threat can be referred to as “catastrophic climate change”.
Global decimation risk	The probability of a loss of 10% (or more) of global population and the severe disruption of global critical systems (such as food) within a given timeframe (years or decades).
Global decimation threat	A plausible and significant contributor to global decimation risk.
Endgame territory	Levels of global warming and societal fragility that are judged sufficiently probable to constitute climate change as an extinction threat.
Worst-case warming	The highest empirically and theoretically plausible level of global warming.