Simply put: Steel et al. (2022)

If you often discuss climate change, there is some thing that you have likely encountered ー doomsday curiosity. People often wonder, will climate change end human civilization? Will it be apocalyptic? Will it be catastrophic? How bad will it get? What phrase can we use and not be exaggerating ー civilizational collapse? An uninhabitable Earth?

 

In this direction, I recently read a fantastic Opinion piece in the Proceedings of the National Academy of Sciences (PNAS) by Daniel Steel et al. It's an opinion piece and not a technical article, and it is clearly and well written. Hence, if you have access, I definitely recommend reading the original thing. But for those without access to this piece, and with similar gnawing questions, here is my attempt to cover their article "Climate change and the threat to civilization".

A sensible vocabulary

The authors write, "Although a body of scientific research exists on historical and archaeological cases of collapse, discussions of mechanisms whereby climate change might cause the collapse of current civilizations has mostly been the province of journalists, philosophers, novelists, and filmmakers. We believe that this should change."

That hit hard, and yes, I completely agree! I have been vexed when faced with questions that clearly came from "information" people got from movies. (Who else is reminded of The Day After Tomorrow? It was hard to imagine that a movie with a paleoclimatologist as the lead would leave me so .. yes, vexed is the best word.)

And so, Steel et al. suggest we start by constructing a useful vocabulary around climate collapse. They offer three scenarios :

1. Local collapse - where society ceases to be functional in specific locations only (e.g. the Syrian civil War)
   
2. Broken world - with widespread collapse, but with some specific locations or countries with somewhat functional (but impaired) societies or governments
3. Global collapse - almost no functional societies or governments, significant decline of the human population

A very significant point arises simply with this list of plausible scenarios. While the other two are potential scenarios, local collapse is already a reality. For Syrians whose whole lives are in Syria, a Syrian collapse is as good as a global collapse. Hence, it is pointless and in fact, inhumane, to ask if local collapses really warrant global consideration. A far more intelligent question to ask (even for the most apathetic) is, What are the odds of a local collapse in my region? Another intelligent question to ask is, At what critical threshold do local collapses start turning into a broken world, and that into a global collapse? In these words, it reminds us of the humbling reality that we don't really know whether we can afford to ignore local collapses and their domino effects.

 

Steel et al. reinforce this with another example, "..what's regarded as catastrophic climate change may differ according to one's location. For instance, the Maldives might view mean global temperature increase of 1.5 ℃ as an intolerable collapse risk, whereas Canada does not". As an Indian living in Canada, this point hits home hard. Every time an Indian political "leader" or a biased journalist parrots the same idiotic point about climate change not being India's fault, I feel like screaming ー yes, but who's responsibility is it to protect India and ourselves? How can you keep fixating on fault to deflect the conversation from responsibility?? In an already hot and humid country owing purely to its geographical location in the tropics, how can we not be alarmed by values such as 1.5 ℃ and 2 ℃? Do we have the leeway to absorb even the 1+ ℃ rise which has already happened? There is simply no point in keeping the same North Star here as countries in the temperate climate zones.

Collapse mechanisms

The next question Steel et al. tackle is of mechanisms. What could lead to these collapse scenarios? They group proposed mechanisms from the literature into three categories:

1. Direct impacts - this relates to the severe and compounding effects of climate change (like extreme heat and droughts), including tipping points, their impacts on important prerequisites for society (like agriculture)
   
2. Socio-climate feedbacks - this relates to the possibilities that climate impacts (such as on food production) could cause societal dysfunction (such as conflicts)
   
3. Exogenous shock vulnerability - this relates to the possibility that already weakened societies may be unable to face external shocks like a war or pandemics

 

This brings to fore another important point -- that it is not simply the direct impacts that we have to be prepared for. In the situation that we somehow successfully adapt to some direct impacts (prepare a sea wall for sea level rise, perhaps), the associated costs may trigger socio-climate feedbacks which could push a society from a weakened-but-adapting stage to a collapse stage. In other words, even if climate adaptation (an imposing challenge in itself) were to be achieved, it may not be the whole solution.

 

Finally, Steel et al. conclude by explaining why building a structured vocabulary around climate collapse is important. "Warnings about climate collapse issued by scientists and scientifically informed public figures are already present in the public discourse, whereas survey data suggest that climate change is a source of widespread public concern and anxiety. Against this backdrop, careful scientific study of climate collapse might act as a counterweight to discussions of climate collapse that are sensationalistic or biased towards portending doom."

 

An excellent read, all in all.

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