An existential risk is an adverse outcome that would either annihilate intelligent life or permanently and drastically curtail its potential (Bostrom 2013).
For example, a big meteor impact or large-scale nuclear war.
Existential risks are not amenable to the reactive (learn from failure) approach of conventional risk management, and we cannot necessarily rely on the institutions, moral norms, or social attitudes developed from our experience with managing other sorts of risks.
Because the consequences are so severe – perhaps the end of human global civilisation as we know
it – “even for an honest, truth-seeking, and well-intentioned investigator it is difficult to think and act rationally in regard to… existential risks” (Bostrom and Cirkovic 2008).
Yet the evidence is clear that climate change already poses an existential risk to global stability and to human civilisation that requires an emergency response.
Temperature rises that are now in prospect could reduce the global human population by 80% or 90%.
But this conversation is taboo, and the few who speak out are admonished as being overly alarmist.
Prof. Kevin Anderson considers that “a 4°C future [relative to pre-industrial levels] is incompatible with an organized global community, is likely to be beyond ‘adaptation’, is devastating to the majority of ecosystems, and has a high probability of not being stable” (Anderson 2011).
He says: “If you have got
a population of nine billion by 2050 and you hit 4°C, 5°C or 6°C, you might have half a billion people surviving” (Fyall 2009).
Asked at a 2011 conference in Melbourne about the difference between a 2°C world and a 4°C world, Prof. Hans Joachim Schellnhuber replied in two words: “Human civilisation”.
The World Bank reports: “There is no certainty that adaptation to
a 4°C world is possible” (World Bank 2012).
Amongst other impacts, a 4°C warming would trigger the loss of both polar ice caps, eventually resulting, at equilibrium, in a 70-metre rise in sea level.
Even at 3°C of warming we could face “outright chaos” and “nuclear war is possible”, according to the 2007 Age of Consequences report by two US think tanks (see page 10).
Yet this is the world we are now entering.
The Paris climate agreement voluntary emission reduction commitments, if implemented, would result in the planet warming by 3°C, with a 50% chance of exceeding that amount.
If these are considered, the Paris emissions path has more than a 50% chance of exceeding 4°C warming.
(Technically, accounting for these feedbacks means using a higher gure for the system’s “climate sensitivity” – which is a measure of the temperature increase resulting from a doubling of the level of greenhouse gases – to calculate the warming.
A median figure often used for climate sensitivity is ~3°C, but research from MIT shows that with a higher climate sensitivity gure of 4.5°C, which would account for feedbacks, the Paris path would lead to around 5°C of warming (Reilly et al. 2015).)
So we are looking at a greater than one-in-two chance of either annihilating intelligent life, or permanently and drastically curtailing its potential development.
Clearly these end-of-civilisation scenarios are not being considered even by risk-conscious leaders in politics and business, which is an epic failure of imagination.
The world hopes to do a great deal better than Paris, but it may do far worse.
A recent survey of 656 participants involved in international climate policy-making showed only half considered the Paris climate negotiations were useful, and 70% did not expect that the majority of countries would fulfill their promises (Dannenberg et al. 2017)
Human civilisation faces unacceptably high chances of
being brought undone by climate change’s existential risks yet, extraordinarily, this conversation is rarely heard.
The Global Challenges Foundation (GCF) says that despite scientific evidence that risks associated with tipping points “increase disproportionately as temperature increases from 1°C to 2°C, and become high above 3°C”, political negotiations have consistently disregarded the high-end scenarios that could lead to abrupt or irreversible climate change.
In its Global Catastrophic Risks 2017 report, it concludes that “the world is currently completely unprepared to envisage, and even less deal with, the consequences of catastrophic climate change”. (GCF 2017)
PRess link for full report: Disaster Alley