Topic 1: How does the discussion of convergent and divergent development models fit into the general framework of sustainability science?

The green revolution has fostered divergent development models in which industry, agriculture, and conservation are partitioned spatially. This has led to the global urbanization trend, abandoned agricultural land, and conservation in specific parcels of land set aside for this purpose. Convergent models pose an alternative in which human activities, agriculture, biodiversity and natural capital are spatially interconnected and evenly distributed across the landscape. In one sense, these alternative scenarios are different ways of managing natural capital to maximize the environmental services that flow from them. Where does this discussion fit into the framework of sustainability science as presented in the seminar, generally?

This is a great question, and a good fit for a very insightful article. The Perfecto and Vandermeer article describes the traditional land-sparing argument that favors rural to urban migration and a consolidation of industrial farms in the assumption that they are more efficient.

The article offers a counter-argument that illustrates examples using modified environmental equations where the number of people working rural land may increase biodiversity, and where strength of the ecosystem matrix plays an important role in maintaining biodiversity, as it allows species to overcome local extinction.

The article also provides a useful example of work within the field of sustainability science. It's interdisciplinary - both in the authors' approach, and in their works cited list. It's also a close look at the intersection of anthropogenic activities (agriculture) and biodiversity. This seems a research subject well situated in sustainability science.

In this paper, the authors explore solutions to two crises - the biodiversity crisis with rates on extinction higher than any time period with humans, and the food availability and access crisis. As before in this seminar, I wonder about how the importance of biodiversity is quantified or put into economic terms. This was discussed some in the last chapter, (section 2.3.3) but mostly to confirm that it's difficult! Still, from a scientific and global sustainability (non-anthropocentric) perspective it seems clear to me that biodiversity is valuable and a sharp extinction rate is indeed a crisis.

I am aware that in many forms of agriculture, biodiversity is NOT a goal. In the US, large scale improvements in overall energy efficiency on corn and soybean farms have been made possible in part by genetically modified crops that are resistant to glyphosate, a broad spectrum systemic herbicide. The energy efficiency is realized when farmers have the run their tractors only once over the fields to spread glyphosate over the crops rather than several times per season as would be required for more traditional physical cultivation.

This method of farming is far different than the small scale farming referred to in the article as practiced by so many farmers in non-industrialized countries. Still, farmers in general are seeking to produce crops for human and animal food (and fiber, fuel etc.), and in many cases crops that will have an economic value. From my own experience farming I know that most of the actual time spent working in IPM or organic fields is practicing some form of killing (reducing biodiversity) - whether it's killing insects, small mammals, or plants out of place (i.e. weeds).

I believe that the net result on agro-ecological or organic farms is still an great increase in biodiversity, especially when soil dwelling micro-organisms are considered, but I still think it's worth considering that most farmers do not seek biodiversity beyond their crop selections as a goal, unless they are enrolled in some sort of conservation land protection, or hedgerow preservation program. The reason I highlight this is that I worry that without an explicit emphasis on the importance of maintaining habitat, and habitat linkages, even farmers who currently operating with low-chemical input, high diversity cultivation techniques may, if given the opportunity, switch to more mechanized, more chemically dependent agriculture that would ultimately reduce biodiversity.

I do see within the Perfecto and Vandermeer paper plenty of room to apply their conclusions in alternative planning and development approaches, but as a sort of "response" paper it seems that outlining the implementation of their ideas was not the main goal. I believe that the basic theories the authors outline are compelling and relevant to further work in agricultural development and planning. This provides good backing and fodder for other sustainability science teams to tackle the land-use, incentive program, development goals questions that this paper helps inform.

Previously Jeannine Cavender-Bares wrote:

The green revolution has fostered divergent development models in which industry, agriculture, and conservation are partitioned spatially. This has led to the global urbanization trend, abandoned agricultural land, and conservation in specific parcels of land set aside for this purpose. Convergent models pose an alternative in which human activities, agriculture, biodiversity and natural capital are spatially interconnected and evenly distributed across the landscape. In one sense, these alternative scenarios are different ways of managing natural capital to maximize the environmental services that flow from them. Where does this discussion fit into the framework of sustainability science as presented in the seminar, generally?

In this week’s seminar, the discussion was often framed as divergent versus convergent models generally; we argue that the answer does not need to be exclusive or universally applied. The tradeoffs between divergent and convergent models are context dependent; for example, living in Arizona is unsustainable as a convergent system if the current population is to be supported.  A convergent model always and everywhere is unrealistic.  So we instead formulate the question as, “When do convergent and divergent models apply?”

To begin to answer this, we identified a few structural constraints on the applicability of one of the models to a particular place: demographic factors, climate, soil type, and governance structure.  (Of course, this list is not exhaustive but rather gives a flavor as to the types of variables we believe to be relevant).  In addition to structural constraints, we suggest dynamic drivers of what model is realized: productivity versus economic profitability, rural-urban economic relations, and national and multi-national economic forces.

With these variables, we are defining the status as a divergent or convergent model to be an emergent property of a complex social-ecological system; worrying whether individuals or institutions should choose one model or the other is therefore irrelevant.  Instead, the important questions for sustainability science are: under what scenarios will the different models emerge, and what are the models’ implications for sustainability?  In addition to considering sustainability outcomes of the two models, we need to assess implications for human well-being across time and space. 

I found the Princeton response thought-provoking: are we willing to let the human-earth interaction models and systems of our future Earth emerge through our actions?  To what extent do we plan?

Backing up, I first would echo what feels like an important statement: that the trade-offs between convergent and divergent models are context dependent.  Further, I would argue that convergent and divergent models may have different characteristics in different places.  This is particularly true in convergent schemes, which rely on diversity; types of crops, the ratio of crop land to nature, etc. will all vary, as the readings acknowledge.

I would also argue that Perfecto (and perhaps myself) envision convergent schemes to exist in diverse contexts, rather than there being only certain contexts where a convergent scheme was better for biodiversity than a divergent scheme.  Thus, even in Arizona, or anywhere where biodiversity exists, some version of a convergent scheme is better than wiping out the land for a mono-cultured plantation.  Of course, even "better" is referring specifically, in this case, to a scenario that "better" preserves the native habitat.

Yet, deciding which "better" is preferred (i.e., in the extreme, a future with more biodiversity or a future without hungry people) is precisely a challenge we should take on.  Thus, I would disagree with the group's notion that individuals and institutions should not worry about which model emerges.  The group suggests that characteristics of the system will organically produce either a divergent or convergent outcome.  However, my understanding of the reading was that the authors' believe (as do I) that society (often driven by market forces) having pushed our development toward adhering to a divergent model.  Thus, we need to proactively plan our development to incorporate convergent schemes (i.e., the agro-ecological matrix model) which are better for our long-term sustainability.

To me, the idea that we can and should "choose" the way we want to develop is more appealing than the idea of watching it emerge through our decisions (revealed preferences).  This is because I believe that humans are limited in their ability to plan, in the short-term, for the long term.  This curse, what economists and psychologists would call quasi-hyperbolic discounting, suggests that individuals discount between period 0 (now) and period 1 (next period) very sharply, but then discount very little between, say, period 10 and 11.  As a result, I think we would too often choose the short term benefits that come from extensive food production now, and plan to adapt a more diverse food growing system, or protect biodiversity, at some later point in the future.    Because the divergent model boosts short-term benefits (greater yields) and long-term costs (reduction in biodiversity), we fall into the trap of making bad decisions which may harm us in the future.  This argument may equally go laterally - we too might suggest we will grow more food here, and save biodiversity somewhere else.

This is where I think planning and policy come in.  Sometimes we need a paternal force (through governments and institutions) to help individuals commit to a future outcome that they would all desire.  If we believe that convergent outcomes are the way to protect biodiversity, and if we as a society determine this is an important long term goal, than planning can help move us in a direction where we are most likely to achieve the outcomes we prefer.  This will be a ethical decision, requiring compromise (arguably the trade-off between short term land profitability and long term environmental sustainability) and acceptance of the implicit risk in planning for any future in our complex and unpredictable Earth system.

Previously Molly O'Connor wrote:

Group response from Princeton:

 

In this week’s seminar, the discussion was often framed as divergent versus convergent models generally; we argue that the answer does not need to be exclusive or universally applied. The tradeoffs between divergent and convergent models are context dependent; for example, living in Arizona is unsustainable as a convergent system if the current population is to be supported.  A convergent model always and everywhere is unrealistic.  So we instead formulate the question as, “When do convergent and divergent models apply?”

 

To begin to answer this, we identified a few structural constraints on the applicability of one of the models to a particular place: demographic factors, climate, soil type, and governance structure.  (Of course, this list is not exhaustive but rather gives a flavor as to the types of variables we believe to be relevant).  In addition to structural constraints, we suggest dynamic drivers of what model is realized: productivity versus economic profitability, rural-urban economic relations, and national and multi-national economic forces.

 

With these variables, we are defining the status as a divergent or convergent model to be an emergent property of a complex social-ecological system; worrying whether individuals or institutions should choose one model or the other is therefore irrelevant.  Instead, the important questions for sustainability science are: under what scenarios will the different models emerge, and what are the models’ implications for sustainability?  In addition to considering sustainability outcomes of the two models, we need to assess implications for human well-being across time and space. 

 

 

Princeton's response:

Elizabeth, thank you for your comments.  You raised good points.  Perhaps our disagreements are mostly differences in emphasis or jargon rather than opposing viewpoints. We would like to further discuss the following two items: 

1. Trade-offs 

2. “Choosing” a convergent model: Guidance versus Legislation

We agree that from a sustainability perspective, the convergent model is attractive. Still, sticking with our example of Arizona or Israel, there are some existing developed areas that just do not have adequate CLIMATE and SOIL to grow enough food to support some version "of the convergent scheme.  We see a few options in applying the convergent model in a location like Arizona (there are tradeoffs):

2. Have the government or an institution "help individuals commit to a future outcome that they would all desire" through the convergent model. If people have a high sense of well-being now, how could institutions convince the population to change? If this actually happens (which seems extremely politically unfeasible), we will see that food does not grow naturally or sufficiently in desert climates to support millions of urban dwellers. 

This second point relates to our comments about emergence.  We believe that a convergent model cannot be created by a central controller, but this CAS view does not imply a fatalistic concept of development.  We can guide a system toward a convergent model, and an important research area in sustainability science is understanding how to do this.

You also raised a good point about the issue of imposing conditions elsewhere.  Considering site-specific well-being implications in addition global sustainability goals is one way to address fairness in encouraging a convergent path.  To take your example, ("a future with more biodiversity or a future without hungry people"), the "we" with the choosing power in that scenario is not going to be the future hungry, we imagine.  There’s a lot that we could say about ecosystem services and well-being—this could be a promising way to continue the discussion on Monday.