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At the Oct. 27 session, Jon Foley at the University of Minnesota presented work from his group and from his collaborators around the globe on "Abrupt Global Environmental Change: Understanding Catastrophic Regime Shifts," followed by commentary from Bill Clark at Harvard University. Discussion focused on the recent Rockstrom et al paper "A safe operating space for humanity" (Nature, 461: 472-475). Faculty and students in the natural and social sciences from the University of Minnesota, Harvard, Arizona State University, Princeton, Florida International University and the Universidad Nacional Autónoma de México participated in the discussion. Jonathan Foley is the Director of the Institute on Environment and McKnight Presidential Chair in the Department of Ecology, Evolution and Behavior at the University of Minnesota. William Clark is Harvey Brooks Professor of International Science, Public Policy and Human Development at Harvard University's Kennedy School of Government. The seminar was hosted by the Minnesota Institute on Environment (IonE) and the National Center for Ecological Analysis and Synthesis (NCEAS).

Jon Foley's Presentation

Foley spoke on the dynamical nature of regime shifts and explained the basis for proposed "safe boundaries" for humanity from Rockstrom et al. Foley's presentation highlighted the fact that we are in a time of massive environmental changes where we may be quickly approaching (or have already surpassed) crucial tipping points that can lead to cataclysmic changes.  He used examples of regime shifts in the Sahel region of Africa to demonstrate the interconnections of climate and vegetation systems where positive feedback mechanisms between the two can set off rapid and nonlinear responses to gradually changing causes once thresholds are crossed.  Despite uncertainties in where the boundaries of safe operating zones for Earth's systems should be set, the concepts of boundaries, complex nonlinearities in system behaviors, thresholds and tipping points should be part of forecasting models and need to enter into policy decisions.  If we wait until we have complete and incontrovertible information before we take action, it may be too late.

Commentary from Bill Clark

Clark responded to the presentation focusing on how the ideas raised in the boundaries paper could interact with the policy domain and influence public debate. He emphasized the important contribution the paper made in defining boundaries as a means to develop clearly defined goals for society. He then raised three problematic issues that need to be considered. First, for boundary-based goals to be effective in stimulating policy they need to be achievable.  Critically, the levers identified to reach them must actually be controllable. Concentrations of substances in the atmosphere or water, for example, cannot be directly controlled. What we really need are boundaries set in terms of the actual variables that we can control, e.g., emissions of CO2 and other green house gases. Second, rather than focusing first on the biophysical analysis, it would be better to integrate a sustainability perspective from the beginning by balancing the risks and benefits of how we use nature to promote sustainable development. Third, there is a scale issue inherent in setting global boundaries. While all the planetary systems were examined from a global perspective, Clark argued that several of the systems need to be regulated at local and regional scales. It is probably not feasible to develop a global treaty on land-use, for example.

Group Discussion

Discussion started with Arnim Wiek at the School of Sustainability at Arizona State, who pointed out the need to consider thresholds and possible tipping points in social systems (poverty, segregation, etc.) as well as in ecological systems. Patty Balvanera from the Center for Ecosystem Studies at the Universidad Nacional Autonoma de Mexico brought up the idea of interrelatedness of the thresholds and suggested that there could be interconnections in the policy arena as well.

Bill Clark's point on the appropriate scales at which to address these problems gave rise to discussion between Clark, Foley and Steve Polasky (an ecological economist from Minnesota) about which planetary systems are global in nature and which are better understood and approached from regional, national or local scales.  While international institutions and agreements were assailed as having a track record of poor efficacy, they were also acknowledged as being essential if we are to have any chance at making headway on issues that are truly global in their nature.   We need to work to establish better international institutions to more effectively deal with global problems and work needs to be done at multiple scales concurrently (global, national and local) to adequately address these problems. Polasky argued that it is not a question of either/or.
The Princeton group asked whether there is research showing positive feedback between the nine variables from the planetary boundaries paper, in ways that amplify changes like we saw in the Sahel case.  In response to Clark's scale argument, they further asked "If we leave the development of regulations regarding these nine variables to local and regional governments, won't that potentially allows for conflicts and/or wars to arise over use of resources rather than if we operate under a global, multi-scale governance system?"

Subsequent email dialogue ensued. Ford Denison, an ecologist at the University of Minnesota agreed with the scale issue raised by Clark. "Two of the three variables that are identified as 'out of bounds' are more local rather than global.  This is true not just in the political sense Clark emphasized, but also ecologically.  Some regions (US Midwest) should use less nitrogen fertilizer, but others should probably use more (parts of Africa), both to increase food production and because increased plant growth sequesters carbon, prevents erosion, etc.  Reducing CO2 emissions anywhere has the same global effect, so global carbon exchanges may make more sense than regional ones, but that's not true for nitrogen.  Similarly, preventing a butterfly from going extinct in Costa Rica will affect local ecotourism, pollination, herbivory by caterpillars, etc., but it won't have any effect on ecosystem function in Tasmania."

Steve Wofsy, an atmospheric chemist and ecosystem scientist at Harvard argued in response to the issue of bringing a sustainability perspective into the analysis from the outset: "My concern is that we cannot predict where sudden changes may happen in the system;  the unpredictability of non-linear coupled systems is just about the only thing we know for certain. A simple example comes to mind--the current functional extinction of white bark pine in large areas of BC and the mountain west. The causes are stand age, climate warming, beetle dynamics in Ponderosa, and the exotic blister rust.  The best model in the world would not predict large scale decline without the invasive rust, which came to N. America around 1900. This example is for a very simple case of abrupt change. Consider chestnut decline for an even simpler example.  More complicated ones will be even more grossly unpredictable."