Showing papers by "Stephen R. Carpenter published in 2010"

Resilience thinking: integrating resilience, adaptability and transformability

Abstract: Resilience thinking addresses the dynamics and development of complex social-ecological systems (SES). Three aspects are central: resilience, adaptability and transformability. These aspects interrelate across multiple scales. Resilience in this context is the capacity of a SES to continually change and adapt yet remain within critical thresholds. Adaptability is part of resilience. It represents the capacity to adjust responses to changing external drivers and internal processes and thereby allow for development along the current trajectory (stability domain). Transformability is the capacity to cross thresholds into new development trajectories. Transformational change at smaller scales enables resilience at larger scales. The capacity to transform at smaller scales draws on resilience from multiple scales, making use of crises as windows of opportunity for novelty and innovation, and recombining sources of experience and knowledge to navigate social-ecological transitions. Society must seriously consider ways to foster resilience of smaller more manageable SESs that contribute to Earth System resilience and to explore options for deliberate transformation of SESs that threaten Earth System resilience.

Ecosystem stewardship: sustainability strategies for a rapidly changing planet

Abstract: Ecosystem stewardship is an action-oriented framework intended to foster the social-ecological sustainability of a rapidly changing planet. Recent developments identify three strategies that make optimal use of current understanding in an environment of inevitable uncertainty and abrupt change: reducing the magnitude of, and exposure and sensitivity to, known stresses; focusing on proactive policies that shape change; and avoiding or escaping unsustainable social-ecological traps. As we discuss here, all social-ecological systems are vulnerable to recent and projected changes but have sources of adaptive capacity and resilience that can sustain ecosystem services and human well-being through active ecosystem stewardship.

Navigating the Back Loop: Fostering Social Innovation and Transformation in Ecosystem Management

Abstract: Addressing the environmental challenges of the 21st century requires substantial changes to the way modern society views and manages ecosystems In particular, many authors contend that fundamental transformation of the largely sectoral, expert-centered ecosystem-management institutions of modern, Western societies is needed There is increasing agreement that more adaptive, integrated, collaborative ecosystem-management approaches, interlinked at multiple scales, would improve society's ability to sustainably manage complex social-ecological systems Therefore, understanding processes of transformation, and factors that may enable transformation in ecosystem management, has become an active research area We explore ecosystem-management transformations using a social-innovation framework Based on three local-level case studies of transformation in freshwater management, we provide a pilot assessment of factors that may promote the emergence and adoption of integrated, collaborative ecosystem-management approaches Our analysis suggests that ongoing environmental degradation, increasing environmental awareness, and shifting societal values are creating fertile ground for the emergence and adoption of new approaches to ecosystem management Based on the case studies we examined, we suggest that initiatives that foster environmental awareness and attachment to local ecosystems, develop capacity for social entrepreneurship in the environmental arena, promote dialogue between key stakeholders, and provide institutional support to new institutions may facilitate the emergence of integrated, collaborative ecosystem-management approaches

Trading carbon for food: global comparison of carbon stocks vs. crop yields on agricultural land.

Abstract: fore, newly cleared land in the tropics releases nearly 3 tons of carbon for every 1 ton of annual crop yield compared with a similar area cleared in the temperate zone. By factoring crop yield into the analysis, we specify the tradeoff between carbon stocks and crops for all areas where crops are currently grown and thereby, substan- tially enhance the spatial resolution relative to previous regional estimates. Particularly in the tropics, emphasis should be placed on increasing yields on existing croplands rather than clearing new lands. Our high-resolution approach can be used to determine the net effect of local land use decisions.

Climate Change and the Integrity of Science

Abstract: We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.

Interacting regime shifts in ecosystems: implication for early warnings

Abstract: Big ecological changes often involve regime shifts in which a critical threshold is crossed. Thresholds are often difficult to measure, and transgressions of thresholds come as surprises. If a critical threshold is approached gradually, however, there are early warnings of the impending regime shift. For example, in a one-dimensional ecosystem dynamics, autocorrelation approaches 1 from below, variance and skewness increase, and variance spectra shift to lower frequencies. Here we focus on variance, an indicator easily computed from monitoring data. There are two distinct sources of increased variance near a critical threshold. One is the amplification of small shocks that occurs as the square of the modulus of the leading eigenvalue (or leading pair of eigenvalues in the complex case) approaches 1 from below. This source, called “squealing,” is well-studied. The second source of variance, called “flickering,” involves brief excursions between attractors. Interacting regime shifts may muffle or magnify variance near critical thresholds. Whether muffling or magnification occurs, and the size of the effect, depend on the product of the feedback between the state variables times the correlation of these variables' responses to environmental shocks. If this product is positive, magnification of the variance will occur. If the product is negative, muffling or magnification can occur depending on the relative magnitudes of these and other effects. Therefore, monitoring programs should measure variates that have opposite responses to the critical transition. If the correlations to environmental shocks have the same sign, the variance of at least one variate will be magnified as the critical transition is approached. Simulation studies suggest that muffling may sometimes interfere with detection of early warning signals of regime shifts. However, more important effects of muffling and magnification may come from their effect on flickering, when random shocks trigger a state change in a system with low resilience. Muffling decreases the likelihood that a random shock will trigger a regime shift. Magnification has the opposite effect. Magnification is most likely when feedbacks are positive and state variables have positively correlated responses to environmental shocks. These results help delimit the conditions when regime shifts are more likely to cascade through complex systems.

Early warnings of regime shifts in spatial dynamics using the discrete Fourier transform

Abstract: In ecosystems with spatial dispersion of nutrients, organic matter, or organisms, dispersal may dampen variability that could provide an early warning of regime shifts. The discrete Fourier transform (DFT) of spatial pattern rescales system dynamics into spatial frequencies where early warnings may be sharpened. We analyzed four spatial ecological models with the DFT. Different models represented single species in discrete and continuous time, and two different prey-harvester systems. In all four systems, the DFT of transient data exhibited substantial increases prior to the critical transitions. The DFT adds to the arsenal of early warning indicators for spatially structured ecosystems. In addition it provides information about the spatial frequencies where destabilization first begins.

Filling holes in regional carbon budgets: Predicting peat depth in a north temperate lake district

Abstract: [1] Peat deposits contain on the order of 1/6 of the Earth's terrestrial fixed carbon (C), but uncertainty in peat depth precludes precise estimates of peat C storage. To assess peat C in the Northern Highlands Lake District (NHLD), a ∼7000 km2 region in northern Wisconsin, United States, with 20% peatland by area, we sampled 21 peatlands. In each peatland, peat depth (including basal organic lake sediment, where present) was measured on a grid and interpolated to calculate mean depth. Our study addressed three questions: (1) How spatially variable is peat depth? (2) To what degree can mean peat depth be predicted from other field measurements (water chemistry, water table depth, vegetation cover, slope) and/or remotely sensed spatial data? (3) How much C is stored in NHLD peatlands? Site mean peat depth ranged from 0.1 to 5.1 m. Most of the peatlands had been formed by the in-filling of small lake basins (terrestrialization), and depths up to 15 m were observed. Mean peat depth for small peat basins could be best predicted from basin edge slope at the peatland/upland interface, either measured in the field or calculated from digital elevation (DEM) data (Adj. R2 = 0.70). Upscaling using the DEM-based regression gave a regional mean peat depth of 2.1 ± 0.2 m (including ∼0.1–0.4 m of organic lake sediment) and 144 ± 21 Tg-C in total. As DEM data are widely available, this technique has the potential to improve C storage estimates in regions with peatlands formed primarily by terrestrialization.

Preparing for the future: teaching scenario planning at the graduate level

Abstract: Are environmental science students developing the mindsets and obtaining the tools needed to help address the considerable challenges posed by the 21st century? Today's major environmental issues are characterized by high-stakes decisions and high levels of uncertainty. Although traditional scientific approaches are valuable, contemporary environmental issues also require new tools and new ways of thinking. We provide an example of how such new, or “post-normal”, approaches have been taught at the graduate level, through practical application of scenario planning. Surveyed students reported that they found the scenario planning course highly stimulating, thought-provoking, and inspiring. Key learning points included recognizing the need for multiple points of view when considering complex environmental issues, and better appreciating the pervasiveness of uncertainty. Collaborating with non-academic stakeholders was also particularly helpful. Most students left the course feeling more positive about the potential contribution they can make in addressing the environmental challenges that society faces.

Control of dissolved oxygen in northern temperate lakes over scales ranging from minutes to days

Abstract: Dissolved oxygen (DO) observations from in situ sensors show complex temporal pat- terns, suggesting that the balance of control by underlying processes changes across scales. At scales ranging from minutes to days, a number of physical and biological processes, such as internal waves, mixing, and ecosystem metabolism, may impart pattern on observed DO. In discriminating the con- trol over DO variability by scale, this helps us to reduce uncertainty in estimates of important eco- system rates, such as gross primary production and respiration. In this study, we examined DO vari- ability over scales ranging from minutes to days and assessed the relative contributions from several physical and biotic drivers. High frequency measurements of DO, wind, temperature, and photosyn- thetically available radiation (PAR) were obtained over periods of approximately 4 d from 25 lakes in northern Wisconsin. Patterns in data were isolated by time scale through wavelet transforms. A suite of predictors were related to DO across time scales using artificial neural networks. At the diel scale, PAR explained most of the variability in DO signals. At sub-diel scales, temperature and wind largely explained variability in DO. However, the nature, strength, and time scale of the relationships between drivers and DO may be a function of lake size.

Changing views of ecological change

Abstract: Ecosystems are always in flux. Paleoecology and long-term ecological research reveal no balance of nature. Instead, ecosystems exhibit periods of rather regular behavior, punctuated by intervals of transition to new modes of behavior [1]. Shifts between intervals of regular behavior can be rapid, or they can last for such a long time that transience itself becomes an object of research. Thus ecological notions of stability are themselves in a phase of turbulent change, with emerging concepts that raise profound questions.