Climate Change, Mortality, and Adaptation: Evidence from Annual Fluctuations in Weather in the US

This paper produces the first large-scale estimates of the US health related welfare costs due to climate change. Using the presumably random year-to-year variation in temperature and two state of the art climate models, the analysis suggests that under a "business as usual" scenario climate change will lead to an increase in the overall US annual mortality rate ranging from 0.5% to 1.7% by the end of the 21st century. These overall estimates are statistically indistinguishable from zero, although there is evidence of statistically significant increases in mortality rates for some subpopulations, particularly infants. As the canonical Becker-Grossman health production function model highlights, the full welfare impact will be reflected in health outcomes and increased consumption of goods that preserve individuals' health. Individuals' likely first compensatory response is increased use of air conditioning; the analysis indicates that climate change would increase US annual residential energy consumption by a statistically significant 15% to 30% ($15 to$35 billion in 2006 dollars) at the end of the century. It seems reasonable to assume that the mortality impacts would be larger without the increased energy consumption. Further, the estimated mortality and energy impacts likely overstate the long-run impacts on these outcomes, since individuals can engage in a wider set of adaptations in the longer run to mitigate costs. Overall, the analysis suggests that the health related welfare costs of higher temperatures due to climate change are likely to be quite modest in the US.

Physical properties of a very diffuse HI structure at high Galactic latitude

The main goal of this analysis is to present a new method to estimate the physical properties of diffuse cloud of atomic hydrogen observed at high Galactic latitude. This method, based on a comparison of the observations with fractional Brownian motion simulations, uses the statistical properties of the integrated emission, centroid velocity and line width to constrain the physical properties of the 3D density and velocity fields, as well as the average temperature of HI. We applied this method to interpret 21 cm observations obtained with the Green Bank Telescope of a very diffuse HI cloud at high Galactic latitude located in Firback North 1. We first show that the observations cannot be reproduced solely by highly-turbulent CNM type gas and that there is a significant contribution of thermal broadening to the line width observed. To reproduce the profiles one needs to invoke two components with different average temperature and filling factor. We established that, in this very diffuse part of the ISM, 2/3 of the column density is made of WNM and 1/3 of thermally unstable gas (T ~2600 K). The WNM gas is mildly supersonic (~1) and the unstable phase is definitely sub-sonic (~0.3). The density contrast (i.e., the standard deviation relative to the mean of density distribution) of both components is close to 0.8. The filling factor of the WNM is 10 times higher that of the unstable gas, which has a density structure closer to what would be expected for CNM gas. This field contains a signature of CNM type gas at a very low level (N_H ~ 3 x 10^19) which could have been formed by a convergent flow of WNM gas.Comment: 13 pages, 12 figures, accepted for publication in A&

Questionnement prospectif à partir de quelques tendances sociales et de leurs impacts sur le loisir

Dans la poursuite d'un questionnement prospectif sur les enjeux du loisir, nous voudrions dégager un horizon de possibilités qui répondent à la question posée par les philosophes anciens: Qu'est-ce que cela vaut-il de pratiquer le loisir ? Ou pour être mieux de son époque: Des loisirs ! Oui, je veux bien, mais pour quoi faire ? Pour élaborer notre vision du loisir, l'identification de quelques tendances sociales significatives est primordiale parce qu'elle révèle un risque pouvant contenir une perte ou un gain à contenir si nous n'agissons pas pour le meilleur. Pour identifier les tendances sociales, nous partirons de la pensée d'auteurs de champ disciplinaires divers en procédant par vagues successives dans une perspective de construction sociale de la réalité, où il est possible après coup d'identifier et de discourir amplement sur certains enjeux du loisir au bénéfice des citoyen(ne)s du monde. In continuing prospective discusssions on ethical and spiritual aspects of leisure, we would like to identify in this paper a broader horizon of possibilities which anwser the questions asked by the ancient philosophers: What is the worth of practicing leisure ? Or, to be more up to date: Leisure expériences ! Yes, of course, but for what for ? In developing the vision of leisure, the identification of social trends is crucial because it indicates a risk that may have a loss or a gain if we do not act now for the better. To identify social trends, we start from the thinking of authors in various disciplines, proceeding by successive waves from the perspective of the social construction of reality, where it is possible afterwards to identify and talk about certain ethical and spiritual aspects of leisure which benefit the world's citizens