Numerical analysis of non-constant pure rate of time preference: A model of climate policy

When current decisions affect welfare in the far-distant future, as with climate change, the use of a declining pure rate of time preference (PRTP) provides potentially important modeling flexibility. The difficulty of analyzing models with non-constant PRTP limits their application. We describe and provide software (available online) to implement an algorithm to numerically obtain a Markov perfect equilibrium for an optimal control problem with non-constant PRTP. We apply this software to a simplified version of the numerical climate change model used in the Stern Review. For our calibration, the policy recommendations are less sensitive to the PRTP than widely believed.     

Time perspective and climate change policy

The tendency to foreshorten time units as we peer further into the future provides an explanation for hyperbolic discounting at an inter-generational time scale. We study implications of hyperbolic discounting for climate change policy, when the probability of a climate-induced catastrophe depends on the stock of greenhouse gasses. We characterize the set of Markov perfect equilibria (MPE) of the inter-generational game amongst a succession of policymakers. Each policymaker reflects her generation's preferences, including its hyperbolic discounting. For a binary action game, we compare the MPE set to a “restricted commitment” benchmark. We compare the associated “constant-equivalent discount rates” and the willingness to pay to control climate change with assumptions and recommendations in the Stern Review on Climate Change.“…My picture of the world is drawn in perspective…. I apply my perspective not merely to space but also to time”—Ramsey.     

Where are the SVHCs?

Background

The European chemicals regulation REACH includes the legal duty for suppliers to inform consumers on request about the presence of substances of very high concern (SVHCs) in articles. Since this requirement has been in force now for 10 years, the intention of this study was to find out whether information on SVHCs is adequately communicated to the consumer today. Data on the presence of SVHCs in articles were collected as a prerequisite for the subsequent requests for a targeted choice of articles to examine the operability of the ‘right to know.’

Results

Literature data show that SVHCs have been measured and described in a large variety of commodities. 32% of 334 information requests for articles which were suspected to contain SVHCs were answered by suppliers and a minor number of these answers were of good quality. Only two respondents indicated the presence of SVHCs in their articles. Suppliers are not legally obliged to respond to requests if their articles are free of SVHCs. Therefore, the absence of a response might be interpreted as an indication that SVHCs are present below 0.1% in the articles in question. However, there are certain doubts that only two out of 334 articles suspected contain SVHCs.

Conclusions

The data question whether the ambitious aims of the SVHC regime can be achieved under the present conditions. Measures are proposed on how to improve implementation of the information requirement and to amend the legal criteria in the upcoming REACH revision.

     

Cover Caption

Cover : Our Lord's candle (Yucca whipplei) occurs in southern California (U.S.A.) and the southwestern Mojave Desert. Several subspecies are restricted to particular geographic locations or floristic provinces. On pages 672‐679, Ferreira and Boldrini review the history of the concept of endemism as it applies to plants. They emphasize that lack of standardization of the geographic extent of endemism complicates classification of species as endemic. On pages 708‐715, Geyer et al. present a method of classifying stresses from climate change that affect different levels of biological organization. Probabilities of persistence of endemic taxa are expected to be highly affected by climate change. Cover image © 2011 Tim Laman. Photographer : Tim Laman ( http://www.TimLaman.com ) is a field biologist and wildlife photojournalist with a Ph.D. from Harvard University. Since 1987, the focus of his scientific research and photography has been the rainforests of Borneo and the Asia‐Pacific region. He is a regular contributor to National Geographic and has published 18 articles in that magazine on topics ranging from endangered species to regions of high species richness under intense pressure from human activities. Tim has also published more than a dozen scientific articles related to rainforest ecology and ornithology. He has a reputation for successfully capturing elusive and critically endangered species in his photographs.     

Combined effect of temperature and food concentration on the grazing rate of the rotifer Brachionus plicatilis

We developed a predictive relationship to determine the grazing rate of Brachionus plicatilis at given temperatures and food concentrations; this function could be applied to experimental culturing and aquaculture practices. Grazing experiments were conducted at temperatures between 5°C and 40°C and at food concentrations, of the flagellate Isochrysis galbana, ranging between ~0 and 10⁶ ml^-1. In total, 136 grazing rates were determined, using the prey depletion method, for rotifers acclimated to treatments for 0.5 or 4 h. The response of grazing rate to temperature and food concentration was described using a model that combined a rectangular hyperbolic function for food concentration and a sigmoidal function for temperature. Using non-linear curve-fitting methods an equation was obtained: G=(452F)/(159000+F)Ǵ.94/(1+2190002T^-4.35) , where G is the grazing rate (flagellates rotifer^-1 min^-1), F is the food concentration (flagellates ml^-1), and T is temperature (°C). The equation indicates a maximum grazing rate of ~35 prey rotifer^-1 min^-1, above ~4᎒⁵ prey ml^-1 and 25°C.     

Minimax regret discounting

The paper considers an environmental policy decision in which the appropriate approach for discounting future costs and benefits is unknown. Uncertainty about the discount rate is formulated as a decision under Knightian uncertainty. To solve this, we employ minimax regret, a decision criterion that is much less conservative then the related criterion maximin—in particular, it can be shown to implement a “proportional response” in that it equally balances concern about the mistake of doing too little with that of doing too much. Despite the criterion's balanced nature, the minimax regret solution mimics a policy that maximizes the present discounted value of future net benefits with an effective (certainty-equivalent) discount rate that declines over time to the lowest possible rate. In addition to reinforcing Weitzman's (1998) original limiting result, the approach generates concrete policy advice when decision makers are unable to specify a prior over possible discount rates. We apply it to the Stern–Nordhaus discounting debate and find that the effective discount rate converges to the Stern rate in just under 200 years.     

Biodiversität von agrarisch genutzten Ökosystemen in den Verhandlungen der COP 9 – Streitpunkt Agrartreibstoffe

The Convention on Biological Diversity (CBD) originating from 1992 today has 190 Parties. In 2000 the convention decided on a programme of work on agricultural biodiversity which explicitly included the diversity of races and types of species used in agriculture. This programme was scheduled for an In-Depth Review at the Ninth Conference of the Parties (COP 9). The preparatory meetings of the Subsidiary Body on Scientific, Technical and Technological Advice (SBSTTA) already indicated that the production and use of biofuels would be a controversial issue during COP. Parties producing biofuels emphasised the CO₂ neutrality while importing countries called for standards for sustainable production. Developing countries mentioned the risk of losing agricultural area suitable for food production and indigenous representatives asked for social standards in agricultural production and respecting of their land ownership. A compromise could only be found at ministerial level during the last conference day, agreeing that all production of biofuels should be sustainable in relation to biodiversity and under this condition urging Parties to promote the production and use of biofuels. Research on the positive and negative impacts of biofuels should be conducted.     

Model selection criteria for overdispersed data and their application to the characterization of a host-parasite relationship

In the statistical modeling of a biological or ecological phenomenon, selecting an optimal model among a collection of candidates is a critical issue. To identify an optimal candidate model, a number of model selection criteria have been developed and investigated based on estimating Kullback’s (Information theory and statistics. Dover, Mineola, 1968) directed or symmetric divergence. Criteria that target the directed divergence include the Akaike (2nd international symposium on information theory. Akadémia Kiadó, Budapest, Hungary, pp 267–281, 1973, IEEE Trans Autom Control AC 19:716–723, 1974) information criterion, AIC, and the “corrected” Akaike information criterion (Hurvich and Tsai in Biometrika 76:297–307, 1989), AICc; criteria that target the symmetric divergence include the Kullback information criterion, KIC, and the “corrected” Kullback information criterion, KICc (Cavanaugh in Stat Probab Lett 42:333–343, 1999; Aust N Z J Stat 46:257–274, 2004). For overdispersed count data, simple modifications of AIC and AICc have been increasingly utilized: specifically, the quasi Akaike information criterion, QAIC, and its corrected version, QAICc (Lebreton et al. in Ecol Monogr 62(1):67–118 1992). In this paper, we propose analogues of QAIC and QAICc based on estimating the symmetric as opposed to the directed divergence: QKIC and QKICc. We evaluate the selection performance of AIC, AICc, QAIC, QAICc, KIC, KICc, QKIC, and QKICc in a simulation study, and illustrate their practical utility in an ecological application. In our application, we use the criteria to formulate statistical models of the tick (Dermacentor variabilis) load on a white-footed mouse (Peromyscus leucopus) in northern Missouri.     

Schadstoffbelastete Erzeugnisse im Verbraucherbereich: Wird REACH zu Verbesserungen führen?

Aim and Background Currently, the protection from hazardous substances occurring in consumer articles is often insufficient. In this paper, we discuss whether this situation will improve relevantly in the course of the implementation of the new European regulation on chemical substances (REACH). Changes under REACH may be heterogeneous. Therefore, differential effects depending on the tonnage as placed on the market, on the amount of substances contained in an article, and depending on timelines and exemptions for meeting the legal requirements, are discussed in this paper, together with a presentation of some uses of substances serving as examples. Discussion and Conclusions If substances are adequately registered, all identified and supported uses including their use in articles should be assessed. Therefore, where the full implementation of the registration conditions applies a substantial improvement may be expected due to REACH. Usually, producers or importers of articles are not required to register substances contained in these articles. Instead, the manufacturer or importer of the respective substance is usually responsible for registration, if exposure to the substance cannot be excluded and emission of the substance from an article is not the intended purpose. This may differ for substances intentionally released from articles. Additional obligations for substances not intentionally released mainly apply to substances of very high concern (SVHC). For the latter, the producer or importer of articles has to notify the European Chemicals Agency (ECHA) on the occurrence of the respective SVHC in articles. This information is important, especially because substances in imported articles may not be registered in advance. Authorisation within REACH is a very far reaching and effective tool of the legislation. However, authorisation is not required for SVHC imported as components of articles. Therefore, one main effect intended by REACH, i.?e. the substitution of SVHC, may possibly be undermined by importers of SVHC in articles. Restrictions, as specified in Annex XVII of REACH, offer a powerful opportunity to improve health and environmental safety with respect to hazardous substances. We support an extended understanding of what is defined as a “substance of concern” in the context of restrictions. This definition should be broader than just what is currently covered by the term SVHC. Consequences of restrictions may equally apply to European producers and importers of articles from outside of Europe, which contain such substances of concern. Another instrument currently closely linked to SVHC (in its more restricted definition), is the obligation of the producer or importer of articles to provide information according to article 33 (REACH). The downstream recipient of an article has to be informed on the content of SVHC in this article and how its safe use is ensured. Warehouses, wholesalers and other traders may therefore be aware of the SVHC contained in articles and may look for substitutes without such ingredients. Also, consumers may request this information on SVHC (just provided on demand) and are thus enabled to decide to buy other articles with less hazardous properties.     

Australian and U.S. News Media Portrayal of Sharks and Their Conservation

Investigation of the social framing of human–shark interactions may provide useful strategies for integrating social, biological, and ecological knowledge into national and international policy discussions about shark conservation. One way to investigate social opinion and forces related to sharks and their conservation is through the media's coverage of sharks. We conducted a content analysis of 300 shark‐related articles published in 20 major Australian and U.S. newspapers from 2000 to 2010. Shark attacks were the emphasis of over half the articles analyzed, and shark conservation was the primary topic of 11% of articles. Significantly more Australian articles than U.S. articles treated shark attacks (χ² = 3.862; Australian 58% vs. U.S. 47%) and shark conservation issues (χ² = 6.856; Australian 15% vs. U.S. 11%) as the primary article topic and used politicians as the primary risk messenger (i.e., primary person or authority sourced in the article) (χ² = 7.493; Australian 8% vs. U.S. 1%). However, significantly more U.S. articles than Australian articles discussed sharks as entertainment (e.g., subjects in movies, books, and television; χ² = 15.130; U.S. 6% vs. Australian 1%) and used scientists as the primary risk messenger (χ² = 5.333; U.S. 25% vs. Australian 15%). Despite evidence that many shark species are at risk of extinction, we found that most media coverage emphasized the risks sharks pose to people. To the extent that media reflects social opinion, our results highlight problems for shark conservation. We suggest that conservation professionals purposefully and frequently engage with the media to highlight the rarity of shark attacks, discuss preventative measures water users can take to reduce their vulnerability to shark encounters, and discuss conservation issues related to local and threatened species of sharks. When integrated with biological and ecological data, social‐science data may help generate a more comprehensive perspective and inform conservation practice. Descripción de Tiburones y su Conservación por Medios Informativos Australianos y Norteamericanos     

Assimilation of dietary free amino acids,peptides and protein in post-larval Atlantic halibut (<Emphasis Type="Italic">Hippoglossus</Emphasis><Emphasis Type="Italic">hippoglossus</Emphasis>)

With the aim of improving the formulation of diets for early stages of marine fish, post-larval Hippoglossus hippoglossus (56 days after first feeding; 23 mg dry weight) were tube-fed liquid diets of radiolabelled L-(¹⁴C) free amino acids (FAA diet), peptides (PEPT diet) and protein (PROT diet), in order to compare the kinetics of transfer from gut into the liver and carcass. The test diets were prepared using equal concentrations of amino acids (AA) and fed as a single pulse (0.3 µl, 2.2 µg AA). The PROT diet consisted of methylated-¹⁴C-labelled (mainly lysine) bovine serum albumin (BSA), the PEPT diet was the PROT diet digested with trypsin and the FAA diet consisted of an amino acid mixture based on BSA composition with added ¹⁴C-lysine. The common labelling with ¹⁴C-lysine permitted a comparison of the three diets. Based on dissection and distribution of the tracer in each compartment, the FAA diet was almost completely absorbed 1 h after the tube-feeding; PEPT and PROT diets required more time before they were processed by the digestive tract. The FAA diet was absorbed about eight times as fast as protein and about six times as fast as peptides from the gut. A low retention of label in the liver for all diets at all sampling times suggests that the liver does not store the AA at these absorption rates. The FAA diet had a higher assimilation efficiency (about 90%) than the PEPT diet (about 12%) and PROT diet (about 32%). FAAs, thus, appear to be superior to protein and peptides as a dietary source of amino acids in post-larval Atlantic halibut.     

The state of Darwinian theory

The year 2009 marked both the bicentenary of Charles Darwin’s birth, and the passage of 150 years since the publication of his revolutionary book, commonly referred to as The Origin of Species (Darwin 1859). As part of the national celebrations that took place in the UK, a meeting on ‘Mathematical Models in Ecology and Evolution’ was held in Bristol on September 10 and 11, with a special focus on the mathematical modelling and application of Darwin’s key theories. This special issue collects together selected papers presented at the meeting, including contributions by the four invited keynote speakers, Rob Boyd, A. W. F. Edwards, Hanna Kokko and Franjo Weissing, as well as papers received after the event. The topics of these papers span the modelling of a very wide range of Darwin’s ideas, particularly evolution through natural selection, the origin of species, sexual selection, altruism and cooperation, and pangenesis, as well as applications of Darwinian thinking to the behaviour of animals, humans, and even human societies. It is hoped that this collection of papers will provide a useful snapshot of the state-of-the-art in Darwinian theory after the last one and a half centuries, and help to identify potential directions for research over the next.     

Sentiment analysis as a measure of conservation culture in scientific literature

Culturomics is emerging as an important field within science, as a way to measure attitudes and beliefs and their dynamics across time and space via quantitative analysis of digitized data from literature, news, film, social media, and more. Sentiment analysis is a culturomics tool that, within the last decade, has provided a means to quantify the polarity of attitudes expressed within various media. Conservation science is a crisis discipline; therefore, accurate and effective communication are paramount. We investigated how conservation scientists communicate their findings through scientific journal articles. We analyzed 15,001 abstracts from articles published from 1998 to 2017 in 6 conservation-focused journals selected based on indexing in scientific databases. Articles were categorized by year, focal taxa, and the conservation status of the focal species. We calculated mean sentiment score for each abstract (mean adjusted z score) based on 4 lexicons (Jockers-Rinker, National Research Council, Bing, and AFINN). We found a significant positive annual trend in the sentiment scores of articles. We also observed a significant trend toward increasing negativity along the spectrum of conservation status categories (i.e., from least concern to extinct). There were some clear differences in the sentiments with which research on different taxa was reported, however. For example, abstracts mentioning lobe finned fishes tended to have high sentiment scores, which could be related to the rediscovery of the coelacanth driving a positive narrative. Contrastingly, abstracts mentioning elasmobranchs had low scores, possibly reflecting the negative sentiment score associated with the word shark. Sentiment analysis has applications in science, especially as it pertains to conservation psychology, and we suggest a new science-based lexicon be developed specifically for the field of conservation.     

Horizontal,vertical and seasonal distributions of epiphytic hydrozoa on the algaHalimeda tuna in the Northwestern Mediterranean Sea

The thalli ofHalimeda tuna (Ellis & Solander) grow horizontally from rocky surfaces and present an upper and lower surface which can be colonized by epiphytes. Thalli ofH. tuna were collected twice a month from March 1985 to March 1986 at Tossa de Mar (northeast Spain). Thirty five species of hydroid were recorded living onH. tuna thalli; of these, the 15 most abundant species were classified into three groups on the basis of their horizontal zonation on the thalli: those most abundant on the proximal, medial or distal articles. Those hydroids common on the proximal (oldest) articles were relatively large and were present throughout the year, those common on the medial articles were smaller and often occurred in dense monospecific patches, while those common on the distal (youngest) articles were present for only short periods and were the most opportunistic hydroids found onH. tuna. We hypothesize that this zonation reflects interspecific niche-selection, enabling successful competition for space with other hydroids, algae and bryozonas. Three hydroid species were more abundant on the upper surfaces of the algae than on the lower, probably because of gravitationally enhanced settlement of planula larvae coupled with (unusually) limited hydrorhizal growth on the underside. Three opportunistic species were more common on the lower surfaces of the thalli, possibly reflecting the greater availability of substratum in the shade, where epiphytic algae were less abundant. Many hydroids declined in abundance in summer because of the death of old thalli, the growth of new thalli and of apical articles on existing thalli, and possibly because of interspecific competition with epiphytic algae. The death of old thalli and the growth of new thalli reduced the abundance of epiphytic algae; this may have facilitated the increase in abundance of hydroids recorded in the autumn.     

Community sustainability: a holistic approach to measuring the sustainability of rural communities in Scotland

ABSTRACT

Although sustainable development was defined in the Brundtland Report almost 30 years ago, the current usage of the concepts of sustainability and sustainable development remain highly equivocal. In the context of rural communities, multiple interpretations and weak definitions lead to confusion in understanding what comprises a sustainable rural community. Building on existing definitions (e.g. Baker’s, 2006, ‘Ladder of Sustainable Development’), models (principally, The Egan Review’s, 2004, ‘Components of Sustainable Communities’) and findings of this study, a sustainable community is defined and a holistic model of a sustainable place-based rural community is presented. This model, the sustainable community design (SCD) is used as the basis for analysing community sustainability, which is measured using mixed methods and scorecard assessment. Sensitivity of the method is demonstrated with inter- and intra-community variations in sustainability across three diverse Scottish rural communities. Intra-community variations illustrate heterogeneity in community sustainability, explain ambiguity in characterisations of an individual community’s sustainability, and highlight the importance of an interdisciplinary and holistic approach to community development. The SCD framework is presented as a useful tool for meso-level sustainability assessment and to facilitate the sustainable development of rural communities.     

Introduction to the Issue

We welcome you to this third issue of the Review of EnvironmentalEconomics and Policy. Once again, this issue includes articles,a symposium focused on a single topic, and a set of regularfeatures. In the first of two articles in this issue, Susmita Dasgupta,Kirk Hamilton, Stefano Pagiola, and David Wheeler describe andassess the history of "Environmental Economics at the WorldBank." This is the first in a series of articles that will describethe role of environmental economics at various government andmultilateral organizations. In this issue, a team of currentand former World Bank economists examines how environmentaleconomics entered the intellectual mainstream at the Bank in1992, and how since then it has exerted a     

Introduction to the Issue

We are pleased to introduce this second issue of the Reviewof Environmental Economics and Policy. Like every issue, thisone includes several articles, a focused symposium, and a setof regular features. In the first of three articles, John Graham describes "The EvolvingRegulatory Role of the U.S. Office of Management and Budget,"where he was the "regulatory czar" as administrator of the Officeof Information and Regulatory Affairs (OIRA) from 2001 to 2006.In his essay, Graham responds to the perception of OMB as antiregulatoryby describing the history of OIRA's proactive     

Note--On the Timing of Greenhouse Gas Emissions Reductions: A Final Rejoinder to the Symposium on "The Economics of Climate Change: The Stern Review and its Critics"

In this final rejoinder to the symposium on "The Economics ofClimate Change: The Stern Review and Its Critics," we respondto comments published in the last issue of this journal by RobertMendelsohn, Thomas Sterner and U. Martin Persson, and John P.Weyant (Mendelsohn et al. 2008). In particular, we examine thepoint of debate with arguably the greatest practical importancefor ongoing negotiations over an international agreement tosucceed the Kyoto Protocol: namely the appropriate timing ofglobal reductions in greenhouse gas emissions. Too often in the past, this debate has been presented as onebetween the poles of "act now" and "wait-and-see". Weyant (seeWeyant's     

Welcome

The Association of Environmental and Resource Economists (AERE)is pleased to launch the Review of Environmental Economics andPolicy with this inaugural issue. The need for a new journal aimed toward a broad audience haslong been recognized by AERE members and has been actively discussedfor several years by the AERE Board. The time was finally judgedright to initiate a careful review of the need and prospectsfor such a journal,