Climate Scientists Blind to ‘Existential Threat’ to HumanityNew Research Warns

A new report suggests that, far from being alarmist, the real social and economic dangers of the climate emergency are outside of boundaries of traditional climate science

Although climate scientists are often accused of being alarmist, new research concludes that they may not be alarmist enough. According to a new study, climate change poses an “existential risk” to humanity that is poorly understood in the scientific literature.

The paper – recently published in the peer-reviewed journal Climatic Change by a team of American and European scientists – explores how climate change can threaten the existence of “an individual person, a community, or nation state or humanity”. It criticises the climate science literature for largely failing to properly understand this existential risk.

The climate science community has rarely delved into the narrative surrounding existential risk, which has been excluded from recent reports by the United Nations Intergovernmental Panel on Climate Change (IPCC). Where the IPCC does recognise existential implications, it is focused on specific things, such as the impact of heatwaves on megacities or the implications of sea-level rise on small island states and low-lying coasts.

To count as an existential risk, climate change needs to affect the latter’s survival directly or the basic human needs on which the latter’s survival depends, the authors suggest. With this framing, it’s far easier to recognise the existential dangers posed by climate change.

The paper points out that research described by IPCC reports recognises the role of “tipping points in climate and other natural and ecological systems which imply irreversible, large-scale processes with positive, self-reinforcing mechanisms if certain thresholds of warming are crossed”.

The problem is that consequences of such processes on human societies and civilisations “are poorly analysed in research and consequently are not fully assessed or treated in depth in the IPCC reports”.

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Wet-Bulb Threat

One of the most devastating but still not widely known consequences of climate change concerns the ‘wet-bulb temperature’ (Tw), which is usually taken as maximum 35°C.

The paper points out that, if global average temperatures rise to 1.5 and 2°C above preindustrial levels – which is likely to happen over the next few decades on a business-as-usual trajectory – this “could affect hundreds of millions of people… especially when combined with urban heat island effects”.

In medium to high emission scenarios, certain regions such as south and south-west Asia would go “beyond the limit of survivability” and more extreme scenarios beyond 7°C “would render large parts of the world uninhabitable”.

These existential risks are particularly serious because, if we breach 1.5°C, we are increasingly likely to trigger climate tipping points that could lead to further abrupt and irreversible global warming.

The current rate of increase in emissions suggests we are heading toward a dangerous 2 to 3°C world. An international team of scientists from the Stockholm Resilience Centre recently warned that we could shoot through even that level into much higher temperature ranges if we trigger multiple tipping points.

But to carefully assess the real nature of the existential risks posed by different climate change impacts, we need a much more robust and precise way of understanding the risks. The paper provides six broad ways of doing so.

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Understanding the Risks

Firstly, we should be specific about “the processes and mechanisms of the threat”. That means clearly identifying “the physical and social processes through which an existential threat is functioning”.

The idea is to figure out which are the key climate or weather-related phenomena – such as storms, floods, landslides, extreme heat and drought, coastal erosion, and loss of snow and glacier ice – and how they could affect people through a threat to life, basic needs, and so on.

Secondly, we should try to identify which parts of human systems will be impacted by these existential threats. For instance, the impact on food production and supply, water resources and availability, or infrastructure and energy, and so on. We also need to remember that these systems are interconnected, which means that an existential threat is likely to affect multiple systems, or to have cascading effects that propagate from one system to another, or others.

Thirdly, we need to find a way to quantify the magnitude of the threat. This could be through obvious metrics like the height and area of floods on inhabited land. This helps to define the thresholds beyond which risks become existential. Other metrics might include the number of people, systems or sectors impacted.

Fourthly, estimating the probability of the threat’s occurrence is crucial. This can be difficult – especially for slow-onset processes like sea-level rise – but crucial to understand how it can effect the speed and magnitude of change. This needs to be coupled with being very specific about the natural and social processes involved, looking at the exposure and vulnerability of a location or region, and what this means for the population.

Fifth, this can be the basis for coming up with a clear sense of the time horizon for the existential risk. The paper notes that “a globalised world and highly interconnected systems may actually increase the speed of risk propagation across countries and continents”. This requires taking into account a range of complex factors, including what happens when technical, economic and societal options to eliminate or reduce risks stop being available because they are overwhelmed by existential changes.

The paper gives the example of rapid and extreme sea-level rise of up to 5 metres. In this scenario, although it might be technically possible to adapt, societal and institutional capabilities may prevent adaptation and instead lead coastal zones to be abandoned.

Finally, the report refers to the “scale” of what will be affected – “from individual to humanity, or from local to global”. Local or regional risks might still be seen as existential if they impact a particularly large fraction of a population or geographical area.

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Interconnection

Ultimately, the new research shows that part of the reason existential risks from climate change have been poorly understood is that they pertain to social, economic, geopolitical and institutional factors that are often outside the boundaries of traditional climate science.

To truly understand the risks, we need to see the connections between the Earth system and the human system.

The fact that we are still only at the earliest stages of being able to do so in a meaningful way throws light on the root of the problem: human societies are operating in a way that fails to recognise the interconnections between planetary and human systems, the way in which our societies are indelibly embedded in the wider environment.

This is a complex, symbiotic relationship – the health and prosperity of our human systems are inseparable from the health and prosperity of our ecosystems.

The new paper takes an important step forward in helping us recognise that our societies urgently need to recognise this relationship if we are to avoid escalating existential threats to humanity.

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