Entropy production and coarse graining of the climate fields in a general circulation model

We extend the analysis of the thermodynamics of the climate system by investigating the role played by processes taking place at various spatial and temporal scales through a procedure of coarse graining. We show that the coarser is the graining of the climatic fields, the lower is the resulting estimate of the material entropy production. In other terms, all the spatial and temporal scales of variability of the thermodynamic fields provide a positive contribution to the material entropy production. This may be interpreted also as that, at all scales, the temperature fields and the heating fields resulting from the convergence of turbulent fluxes have a negative correlation, while the opposite holds between the temperature fields and the radiative heating fields. Moreover, we obtain that the latter correlations are stronger, which confirms that radiation acts as primary driver for the climatic processes, while the material fluxes dampen the resulting fluctuations through dissipative processes. We also show, using specific coarse-graining procedures, how one can separate the various contributions to the material entropy production coming from the dissipation of kinetic energy, the vertical sensible and latent heat fluxes, and the large scale horizontal fluxes, without resorting to the full three-dimensional time dependent fields. We find that most of the entropy production is associated to irreversible exchanges occurring along the vertical direction, and that neglecting the horizontal and time variability of the fields has a relatively small impact on the estimate of the material entropy production. The approach presented here seems promising for testing climate models, for assessing the impact of changing their parametrizations and their resolution, as well as for investigating the atmosphere of exoplanets, because it allows for evaluating the error in the estimate of their thermodynamical properties due to the lack of high-resolution data. The findings on the impact of coarse graining on the thermodynamic fields on the estimate of the material entropy production deserve to be explored in a more general context, because they provide a way for understanding the relationship between forced fluctuations and dissipative processes in continuum systems

Thermodynamic efficiencies of an idealized global climate model

We employ the heat engine framework to derive a simple method for assessing the strength of irreversible processes in global climate models (GCMs). Using the explicit energy budget of an idealized GCM, we show that the thermodynamic efficiencies based on the net heating rate and frictional work rate provides a measure of physical and numerical irreversibilities present in either open (e.g., the Hadley circulation) or closed (e.g., the general circulation) circulations. In addition, we show that the Carnot efficiency is useful for assessing the maximum possible efficiency attained by closed circulations. Comparison of the work-based efficiency with that based on the net heating rate and the Carnot efficiency provides a gauge of how close to reversible and ideal the circulations are. A series of experiments with the idealized GCM demonstrate the usefulness of our method and show the sensitivity of an essentially reversible model to changes in physical and numerical parameters such as rotation period and resolution.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47143/1/382_2005_Article_71.pd

Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies

The study of the collapse of past societies raises many questions for the theory and practice of archaeology. Interest in collapse extends as well into the natural sciences and environmental and sustainability policy. Despite a range of approaches to collapse, the predominant paradigm is environmental collapse, which I argue obscures recognition of the dynamic role of social processes that lie at the heart of human communities. These environmental discourses, together with confusion over terminology and the concepts of collapse, have created widespread aporia about collapse and resulted in the creation of mixed messages about complex historical and social processes

‘I’m here as a social worker’: immigration status issues and safeguarding children in Private Fostering arrangements in the UK

Private fostering of non-citizen children in the UK has become a focus of child protection social work since the Laming report into the death of Victoria Climbié. This paper reports on a qualitative study that aimed to understand children’s experiences of private fostering and social work practice. The study involved interviews with social workers and privately fostered children, reviews of advice line calls to Children and Families Across Borders and a review of safeguarding reports in London Boroughs. We found that many children who present as ‘privately fostered’ have been in effect abandoned by their parents and are living with strangers. While the homes they live in may be safe, their insecure immigration status renders them vulnerable and in addition, if not regularised, will lead to complicated and stalled transitions to adulthood. The key findings of thisstudy are that children whose parents are not resident in the UK are treated as privately fostered but the underlying premise of private fostering legislation, which is that the parent retains meaningful responsibility for the child, is often not in place

Parents at their best: The ethopolitics of family bonding in France

International audienceIn France, the concept of 'parentality' has become a key notion in the field of social work since the mid-1990s. This idea serves mostly as a basis for professional evaluations of parents' ability. However, it does not only prescribe behaviors and implement norms; it has also transformed the way people consider their own family attachments, and adjust individually to new ethical definitions of selves. Based on two complementary ethnographic field studies – one looking at the administrative management of adoption and the other at medical care provision for maternal mental health – this article shows how discourses and practices about parentality serve a policy of self-reform. This article therefore questions how politics of control and regulation that are deployed in the privacy of the family sphere act on an ethical level by inviting subjects to reform themselves for their own good and for the good of others