Thresholds of sustainability - Umbrales de sostenibilidad

Este post también andaba entre los pendientes. Cuando asistí a República Dominicana a entrevista me encontré con el tema de los "Umbrales de Sostenibilidad" o "Thresholds of sustainability" . Es un concepto interesante que tiene que ver con una especie de "momento de quiebre". Más o menos así es como lo comprendí: hay momentos en que nos sorprendemos de un cambio abrupto (el concepto es originalmente utilizado en los ecosistemas, pero se ha aplicado a situaciones sociales también. Por facilidad, lo aplico a lo ecológico) en las condiciones de un sitio: supongamos el derrumbe de una gran montaña. (Más en "seguir leyendo"

Para muchos, el cambio podría ser "una sorpresa", algo inesperado, sin embargo, el concepto de los "umbrales..." nos explica que para que eso sucediera, pasaron una serie de pequeñas acciones casi imperceptibles -por la diferencia de análisis entre los tiempos humanos y los de la naturaleza, por ejemplo- que se fueron sumando hasta que provocaron este cambio que es brusco a los ojos, pero que en uno u otro momento tendría que suceder. 

Luego entonces, el estudio de los "umbrales..." nos permitiría ir identificando los factores que intervienen en un cambio mayor y en la medida en que los analicemos, lleguemos a pronosticar el momento de rompimiento. 

 El concepto me parece super interesante, pero bastante complejo en su estudio, pues parece necesitar de un análisis muy largo en el tiempo (una gran cantidad de data), sin embargo, me llamó mucho la atención, porque aplicado a ciencias sociales, podría tener que ver con el momento en que se desatará la revolución, la crisis financiera, etc. Seguramente en el campo humano será aún más complejo, pero sería útil conocer los diferentes factores y a través de su suma y análisis saber, por ejemplo, si Calderón se cae antes del 2012 o si lo tenemos que aguantar los 6 años completos... 

 Yo me imaginé una cuchara que está balanceada perfectamente sobre un vértice: para que suceda un cambio irreversible y totalmente perceptible se tiene que poner peso sobre uno de los costados y la resistencia es "X", pero llega un momento en que la suma de factores (viento, peso del material, prsión ejercida...) llegan a un punto en que la cuchara perderá el balance y terminará por caer. El estudio de los "umbrales..." habría consistido en adivinar el momento en que se rompería el equilibrio y se ocasionaría el cambio. ¿Cachai? 

 En el título del post, un link interesante a un estudio de umbrales sobre el momento en que se enciende el petróleo en distintas superficies. Acá abajo algunas de las notas que tomé, por si te sirven las direcciones electrónicas o los comentarios. 

(ref: http://ejournal.nbii.org/archives/vol3iss2/communityessay.lyytimaki.html) Thresholds of sustainability: policy challenges of regime shifts in coastal areas Jari Lyytimäki1 & Mikael Hildén2 1 Research Programme for Environmental Policy, Finnish Environment Institute, PO Box 140, FI-00251 Helsinki, Finland (email: jari.lyytimaki@ymparisto.fi) 2 Research Department, Finnish Environment Institute, PO Box 140, FI-00251 Helsinki, Finland (email: mikael.hilden@ymparisto.fi 

  Este asunto trata de los "umbrales" representados como el punto en que se presenta un cambio en un ecosistema 

 Despite their intuitive appeal, it is difficult to define a threshold exactly. The common definition refers to the level of a stressor that triggers an abrupt change in ecosystem quality, property, or phenomenon. It implies that relatively small changes in environmental drivers can produce large responses in ecosystems (Groffman et al. 2006). 

  Estos cambios pueden ser de diferentes tipos, y ubicarse en distintos tiempos: unos dentro del "tiempo humano" y otros fuera de él (por demasiado lentos o por excesivamente rápidos, al grado que no piensas que son un cambio de umbral) 

 The following sections use thresholds in a broad sense to describe nonlinear changes that can be attributed to increasing (or decreasing) pressures. As is shown, the systems can respond in many ways: 

Ecological thresholds do not just refer to sudden jumps in a time series. They imply nonlinear dynamics, with possibilities for alternative stable states, regime shifts, hysteresis, and points of no return. In practice, it is difficult to assess whether a certain dramatic change is caused by essentially nonlinear dynamics or by stochastic events. The consequences of passing an ecological threshold can, furthermore, be of different types. A change in the mean value of a variable is only one consequence. In other cases, the variances of individual system components may increase, or mass flows and functional relationships between system components may change. The ecosystem-health approach seeks to identify several variables that, taken together, would indicate a systemic shift from a healthy to a compromised system (Rapport, 2006). 

 The concept of ecosystem health argues in a related way that sudden degradation of the state of a system occurs not as a consequence of a gradual change in a single pressure, but of the cumulative effect of a number of stressors leading to an ecosystem-distress syndrome (Rapport et al. 1985; Hildén & Rapport, 1993). 

 Even when trespassing a threshold suddenly changes system feedbacks, the resulting changes can be slow. Hysteresis refers to instances where there may be significant time lags between a pressure change and a corresponding change in an ecosystem. Hysteresis was originally used to describe physical systems that do not instantly follow the forces applied to them, but instead react slowly, or do not, with the passage of time, return completely to their original state. In some cases, the original environmental state can be reached after the change, but the return path is drastically different from the development that caused the altered state. 

 When a threshold has been passed, it may be impossible to recover the system’s original state. For example, certain species can survive in a degraded environment for some time, especially if temporary conditions, such as the weather, are favorable. Eventually these species will, however, go extinct. This inevitability of extinction is what ecologists call extinction debt (e.g., Hanski & Ovaskainen, 2002). Extinction is perhaps the most fundamental ecological threshold and is usually seen as irreversible, a point of no return, even though it is in theory possible to reintroduce a locally extirpated species with the help of gene banks, zoos, or the introduction of individuals from elsewhere (see Caro, 2007). However, the loss of a species may drastically alter the ecosystem itself. Even if the species is reintroduced, it may not be able to establish viable populations because the ecosystem dynamics have changed. 

 Systems often shift gradually from one state to another rather than changing suddenly at a specific point (Huggett, 2005). An analogy can be found in the first and second order transition of physical systems. In a first order transition the actual threshold level, such as the boiling point of water, is exactly defined. In second order transitions only the definitive loss of characteristics, such as the loss of magnetism in iron as a consequence of heating, is well defined, whereas the process is distinguished by an accelerating change towards the loss. 

 Perception of the threshold depends on the timescale. Timescales relevant for everyday life or policy making may be much too short for certain regime shifts, such as some impacts of climate change that may transpire over hundreds or thousands of years. However, on geological or evolutionary timescales these changes are quite rapid. Other modifications, such as lakes that shift from clear to turbid, standing water that becomes overgrown by floating plants, or coral reefs that lose color, can occur within timescales that are easily grasped by citizens, policy makers, and journalists because they correspond to human scales (Adam, 1998; Lyytimäki, 2007). At the other end of the spectrum are changes that occur so fast that humans do not typically think of them as thresholds. For example, the succession of bacterial species in decaying organic material is likely to pass unnoticed. Due to this variability, studies describing ecological thresholds must be done at different temporal, spatial, and structural scales (Groffman et al. 2006). 

  Hay una relación entre estos "saltos" de umbrales y la acción del hombre: las situaciones políticas (presiones, discusiones y críticas sociales, por ejemplo) pueden hacer que se tomen decisiones sobre determinadas condiciones de un área y al aplicarse cambios, éstos aceleren un cambio de umbral 

 Sociotechical transitions are no less complicated than nonlinear ecosystem changes. They arise as a set of connected changes that reinforce one another but take place in several different areas and at various scales, such as macrolevel cultural changes, meso-level institutional changes, and microlevel changes in beliefs and attitudes. For example, extensive media coverage in Finland of intensive algal occurrences during the summer of 1997 increased pressure to improve the monitoring and communication about algal blooms, both in the country’s inland waters and in the Baltic Sea. As a result, in 1998 a nationwide monitoring program was launched that has provided the media with easy-to-use information (Lyytimäki, 2007). In this case, the intensive algal blooms were the trigger that, together with gradually increased public awareness about eutrophication, changed the social process (Peuhkuri, 2002). 

  Y la relación que puede existir entre los umbrales ecológicos y las transiciones sociales es explicada acá bajo el concepto de "Panarquía" (como opuesto al concepto de jerarquía): 

 The interplay between ecological thresholds and social system transitions can be described using the concept of panarchy, a term created as an antithesis to the word hierarchy (Gunderson & Holling, 2001). Panarchy views coupled human-natural systems as a cross-scale set of adaptive cycles that reflect the dynamic nature of human and natural structures across time and space. Sudden shifts in ecosystem states can induce changes in human understanding of the way the systems need to be managed. These modifications, in turn, may alter the institutions that carry out management and, as a result, prompt new changes in ecosystems. In these cases, the concept of thresholds is useful in policy, but only post festum–as a way to interpret an otherwise confusing situation and to understand and justify changes. 

  Este trabajo es sobre estos umbrales en áreas costeras y cómo deben monitorearse. El autor se pregunta cuál es el momento apropiado para intervenir antes de que se den los saltos en los umbrales, y para ello plantea que el monitoreo es una base elemental, así como la planificación, dadas las posibilidades e intereses de la sociedad de los posibles resultados de la llegada a ese "umbral". Agrega también que si se realiza todo el trabajo de monitoreo, el grupo que lo hace, debe estar en capacidad de poder tomar acciones al respecto cuando sean necesarias. 

 Y es un hecho que si no se cuenta con suficientes indicadores y si se mira todo como un acercamiento linear, no se estarán dando las respuestas adecuadas, pues requiere de un acercamiento múltiple. 

To summarize, evidence is accumulating that threshold behavior chacterizes many systems, but this does not mean that thresholds are found in every system or in every situation. Even when they exist, it remains difficult to identify them and to predict when the critical limits are likely to be reached. But based on our current knowledge of ecological thresholds, the poet T. S. Eliot was not completely right. While many systems may change with a whimper, others can undoubtedly change with a bang or with a grand AH-WHOOM. Humankind should learn to cope with this possibility.