In the journal PNAS, an opinion article by a group of scientists calls for the study of the possible collapse of civilization due to climate change.

The authors define the collapse of civilization as the loss of a society's ability to maintain basic governance functions related to security, law and order, and the provision of basic necessities, such as food and water. Civilizational collapse has extremely negative consequences for humanity by causing violence, conflict, and extreme scarcity.　　

The authors consider three collapse scenarios of progressively increasing severity.

• Collapse in specific vulnerable regions
• Cases in which some cities or countries collapse and the rest of the world suffers negative climate-related impacts such as food and water shortages
• Global collapse, where all large urban areas around the world are abandoned, functioning nations no longer exist, and the world's population declines

According to the authors, the possibility that the collapse of civilization due to climate change raises ethical and scientific complexities and may proceed in different processes in time and space. As an ethical example, the Maldives might view mean global temperature increase of 1.5°C as an intolerable collapse risk, whereas Canada does not. Also, from a scientific perspective, local cases of civilizational collapse have been studied by historians and archaeologists, but the mechanisms by which these local cases may evolve into a broken world or global collapse are only speculative.

The mechanisms have not been adequately studied for the direct effects of climate change, such as rising sea level, drought, flooding, extreme heat etc., which pose a risk of collapse. The authors point out that climate change also has indirect effects on trade and international cooperation that may lead to political conflict and dysfunction. These effects undermine the adaptive capacity of civilized societies and increase their vulnerability to other types of shocks such as wars or pandemics.

The authors argued for the importance of a scientific and systematic analysis of the mechanisms of the civilizational collapse crisis brought about by climate change.

Reference
Daniel Steel et al, Climate change and the threat to civilization, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2210525119

Contributor: IIYAMA Miyuki (Information Program)