Climate Change & Social Strife: Tales of Tree-rings

Today in Nature's new Climate Change journal a paper has come out linking climate change  to dramatic social upheavals in the early centuries of the last millennium. A team of Swiss researchers, led by paleoclimatologist Ulf Büntgen, analyzed tree-ring data to create a year-by-year profile  of Europe's climate from 500BC until today.  They then looked at how those climatic trends related to periods of social change.  Here's what they found:

From the middle of the third to the sixth centuries, Europe experienced barbarian invasions, political turmoil and economic dislocation. In general, rapidly fluctuating climate, combined with population declines brought about by frequent epidemics, dramatically trimmed crop yields produced by the region's largely agrarian societies during that period.

This is not the first time that the link has been made between changes in climate, declines in key resources, and conflict. But the mixture of social history and tree-ring analysis is interesting and unusual. What it means going forward into another period of climate instability is of course the key question.

The authors point out that while we may be more able to adapt to or reduce the severity of changes in our climate, we are also cut off from one of the most common responses to a changing climate: migration.

The other main difference of course is that we are now an urban species. What impact will  that have on our ability to weather the storm? On the one hand, well designed cities can protect inhabitants from the worst impacts of a changing climate. On the other -- as another article in today's Nature Climate Change makes clear -- urban populations may also feel the heat far more than they do today with drastic increases in heatwave frequency and mortality (among other types of environmental stress).

Building cities to cope with these types of variations in climate is often framed as a technical challenge:  more shade trees to cool the streets, better water recycling processes to make the most of a scarce resource, local agriculture and the restoration of watersheds to preserve ecosystem services.  Those are all parts of the puzzle, but we can't forget the social component of our cities.  The culture of our cities -- how we govern ourselves, make collective decisions, and reduce inequalities -- will have a huge influence over how prepared our cities are, and how resilient human society is to change.


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This is a blog for news and views on the future of sustainable cites. A major revamp is in the works. Until then I am keeping this version up as an archive of my past writing.

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