Tag: regime change

All of this has happened before

Although summers are quite busy, usually I try to find the time to read several books that have been occupying the corner of my desk during the academic year. I have finally read a book on my “meaning to get to” list for years: “Prehistoric Native Americans and Ecological Change,” (Cambridge University Press), by the professors who taught me landscape ecology, Paul and Hazel Delcourt.

Originally published in 2004, the book combines archaeology and paleoecology to describe how landscapes in North America were changed by human societies long before Europeans arrived. Ecologists especially have always believed that pre-European societies had little lasting impact on ecosystems in North America. This belief underpins many conservation biology targets for habitat and species restoration. However, the Delcourts describe thriving human societies in Ontario, southern Illinois and Eastern Tennessee that used fire and forest harvesting to support their agriculture-based societies, dramatically increasing nut-bearing trees and pioneer species (such as ragweed) at the expense of species adapted to mature forests. These changes, made at increasingly large scales, may have also increased herbivore species such as white-tailed deer that thrive in early-successional and edge woodland habitats.

The book is framed by Panarchy theory, and explains how these changes, when they reached a critical proportion of the surrounding landscape, created greater disturbances (such as floods) that likely led to the area being abandoned by these societies, long before Europeans arrived on the scene. These events are a reminder that humans, like all species, alter their environments. Sometimes these alterations are beneficial in the short term, but often they are detrimental in the long term. Even with small-scale disturbances (such as slash-and-burn agriculture), if the period allowed for ecosystem regeneration is too short, soil fertility can decline and ultimately the practice becomes unsustainable.

Of course, the lessons we gain from the distant past (14,000 to 500 years before present) are limited in their applicability. North America is now home to over 400 million people, almost two orders of magnitude larger than it has ever supported before. It may be that the agricultural and settlement practices of even the most sustainable of these early societies would be completely unsustainable today. But what we can learn is that our impacts will certainly be available for study for a long, long time.


Losing a global carbon sponge

A paper published last week in Nature reviewed a growing body of evidence that suggests that a profound loss of forest cover in the Amazaon would have worrying consequences for the rest of the planet.

In “The Amazon basin in transition“, Davidson et al. describe how the impacts of agricultural expansion and climate events such as El Niño can conspire to destroy even more forest through drought- and fire-induced deforestation. When trees die or burn, they release carbon into the atmosphere. If more trees are destroyed than grow to replace them, more carbon is released than is absorbed; the Amazon sink becomes a source. According to the article, the Amazon rainforst currently sequesters roughly 100 billion tons of carbon, an amount equivalent to the carbon release from a decade’s worth of fossil fuel use.

Currently forest cover has been reduced to about 80% of its original area; the article suggests that if forest cover approaches 40%, a critical transition from forest to savanna may occur, given feedbacks between tree cover and precipition (see our summary in Science). If this occurs, we might witness what happens with the lost of “the lungs of the planet“.


Managed collapse

Contributed by: Audrey Mayer

Ernest Callenbach has an interesting new article in the Solutions journal, entitled “Sustainable Shrinkage: Envisioning a smaller, stronger economy“. He discusses the ways in which we can modify our existing systems to fit within natual resource limits and avoid collapse. These solutions rely heavily on new policies (to encourage different behaviors) and technologies, with considerable assumptions about population growth and reorganization at the local scale. It’s a good (if a bit superficial) read, with many good ideas that will not work at the scale he is envisioning, in my humble opinion.

A substantial part of my research program uses statistical theory to develop indicators for when complex systems (especially human-environment or “socioecological” systems) are about to collapse. In particular, my colleagues and I have tried to apply a statistic called Fisher Information, which is a measure of the predictability of a system over time; the more predictable the system, the higher Fisher Information is. Complex systems tend to have many negative (stabilizing) feedbacks that keep the system’s behavior relatively stable and predictable. As these stabilizing feedbacks deteriorate, the system’s behavior becomes more erratic and hence more difficult to predict. At the peak (or valley?) of collapse, that system could go in one of many typically unpredictable directions. As that system begins to reorganize, new stabilizing feedbacks develop and settle the system into a new operating state, becoming more predictable again. In our work, we have seen a drop in Fisher Information just prior to system collapse, and then Fisher Information increases as these systems reorganize.

The question Callenbach poses is this: can we somehow guide our systems through this collapse and reorganization process with a minimal loss of order? He is not the only one to ask this question. There is a growing literature* which provides ample evidence that large human-environment systems (such as nations or empires) can and do undergo collapse and reorganization regularly…. the current events in the Middle East illustrate this quite well. Typically the reorganization is slow, disorderly, and unpredictable.

My short, pessimistic answer to Callenbach’s question is no: we cannot manage our large, socioecological systems through a collapse and reorganization without substantial disorder. We cannot predict how any new, large system will function, nor when it will function with any predictability. I argue that the self-organizing dynamics at the scale of, say, the United States federal government, are far too large and powerful, and we understand them too poorly, to trust that federal policies and large technological solutions will help us glide to a smarter, more sustainable future. Instead, I think these changes must occur at smaller, more manageable scales: the individual, the family, the local community. At these scales, we can understand and influence the dynamics and feedbacks, and reorganize into functional units. This is not to say that all of Callenbach’s solutions are wishful thinking: creating more durable goods and stronger social ties (and reducing the consumption of cheap products made far away with cheap labor) are solutions that have been advanced from many corners. These are solutions that are more tenable at the small scale…. they will have to propogate up to the larger systems.

*These include books such as Joseph Tainter’s Collapse of Complex Societies“, Jared Diamond’s Collapse: How societies choose to fail or succeed“, Dmitry Orlov’s humorous “Reinventing collapse: The Soviet example and American prospects“, Chris Martenson’s The Crash Course: The unsustainable future of our economy, energy and environment,” among many others.