Geometric and projection effects in Kramers-Moyal analysis

Kramers-Moyal coefficients provide a simple and easily visualized method with which to analyze stochastic time series, particularly nonlinear ones. One mechanism that can affect the estimation of the coefficients is geometric projection effects. For some biologically-inspired examples, these effects are predicted and explored with a non-stochastic projection operator method, and compared with direct numerical simulation of the systems' Langevin equations. General features and characteristics are identified, and the utility of the Kramers-Moyal method discussed. Projections of a system are in general non-Markovian, but here the Kramers-Moyal method remains useful, and in any case the primary examples considered are found to be close to Markovian.Comment: Submitted to Phys. Rev.

Finite sampling interval effects in Kramers-Moyal analysis

Large sampling intervals can affect reconstruction of Kramers-Moyal coefficients from data. A new method, which is direct, non-stochastic and exact up to numerical accuracy, can estimate these finite-time effects. For the first time, exact finite-time effects are described analytically for special cases; biologically inspired numerical examples are also worked through numerically. The approach developed here will permit better evaluation of Langevin or Fokker-Planck based models from data with large sampling intervals. It can also be used to predict the sampling intervals for which finite-time effects become significant.Comment: Preprin

Fourteen propositions for resilience, fourteen years later

In 2006, Walker et al. published an article titled, “A Handful of Heuristics and Some Propositions for Understanding Resilience in Social-ecological Systems.” The article was incorporated into the Ecology and Society special feature, Exploring Resilience in Social-Ecological Systems. Walker et al. identified five heuristics and posed 14 propositions for understanding resilience in social-ecological systems. At the time, the authors hoped the paper would promote experimentation, critique, and application of these ideas in resilience and social-ecological systems research. To determine the extent to which these propositions have achieved the authors’ hopes, we reviewed the scientific literature on socialecological systems since the article was published. Using Scopus, we identified 627 articles that cited the Walker et al. article. We then identified and assessed the articles relative to each proposition. In addition, we conducted a more general Scopus review for articles that did not cite the Walker et al. article specifically but incorporated a proposition’s concepts. Overall, articles often cite Walker et al. as a reference for a definition of a heuristic or ecological resilience generally and not to reference a specific proposition. Nonetheless, every proposition was at least mentioned in the literature and used to advance resilience scholarship on social-ecological systems. Eleven propositions were tested by multiple articles through application of case studies or other research, and 7 of the 11 propositions were substantially discussed and advanced. Finally, three propositions were heavily critiqued either as concepts in resilience literature or in their application

Potential feedbacks between loss of biosphere integrity and climate change

Non-technical abstract Individual organisms on land and in the ocean sequester massive amounts of the carbon emitted into the atmosphere by humans. Yet the role of ecosystems as a whole in modulating this uptake of carbon is less clear. Here, we study several different mechanisms by which climate change and ecosystems could interact. We show that climate change could cause changes in ecosystems that reduce their capacity to take up carbon, further accelerating climate change. More research on – and better governance of – interactions between climate change and ecosystems is urgently required. Technical abstract Individual responses of terrestrial and marine species to future climate change will affect the capacity of the land and ocean to store carbon. How system-level changes in the integrity of the biosphere interact with climate change is more uncertain. Here, we explore the consequences of different hypotheses on the interactions between the climate–carbon system and the integrity of the terrestrial and marine biospheres. We investigate mechanisms including impairment of terrestrial ecosystem functioning due to lagged ecosystem responses, permafrost thaw, terrestrial biodiversity loss and impacts of changes in marine biodiversity on the marine biological pump. To investigate climate–biosphere interactions involving complex concepts such as biosphere integrity, we designed and implemented conceptual representations of these climate–biosphere interactions in a stylized climate–carbon model. We find that all four classes of interactions amplify climate change, potentially contributing up to an additional 0.4°C warming across all representative concentration pathway scenarios by the year 2100 and potentially turning the terrestrial biosphere into a net carbon source, although uncertainties are large. The results of this preliminary quantitative study call for more research on – and better integrated governance of – the interactions between climate change and biosphere integrity, the two core ‘planetary boundaries’.The research leading to these results has received funding from the Stordalen Foundation via the Planetary Boundary Research Network (PB.net), the Earth League’s EarthDoc programme, the Leibniz Association (project DOMINOES), European Research Council Synergy project Imbalance-P (grant ERC-2013-SyG-610028), European Research Council Advanced Investigator project ERA (grant ERC-2016-ADG-743080), Deutsche Forschungsgemeinschaft (DFG BE 6485/1-1), Project Grant 2014-589 from the Swedish Research Council Formas and a core grant to the Stockholm Resilience Centre by Mistra

Social-ecological connections across land, water, and sea demand a reprioritization of environmental management

Despite many sectors of society striving for sustainability in environmental management, humans often fail to identify and act on the connections and processes responsible for social-ecological tipping points. Part of the problem is the fracturing of environmental management and social-ecological research into ecosystem domains (land, freshwater, and sea), each with different scales and resolution of data acquisition and distinct management approaches. We present a perspective on the social-ecological connections across ecosystem domains that emphasize the need for management reprioritization to effectively connect these domains. We identify critical nexus points related to the drivers of tipping points, scales of governance, and the spatial and temporal dimensions of social-ecological processes. We combine real-world examples and a simple dynamic model to illustrate the implications of slow management responses to environmental impacts that traverse ecosystem domains. We end with guidance on management and research opportunities that arise from this cross-domain lens to foster greater opportunity to achieve environmental and sustainability goals.Peer reviewe