Pop-up landscapes: a new trigger to push up land value?

Through a qualitative analysis of pop-up landscapes on Philadelphia’s Delaware Waterfront, this paper examines how entrepreneurial urban actors, such as municipal officials, urban planning agencies, and landscape designers, strategically harness to catalyze investment. While pop-up landscapes have disrupted negative associations with the waterfront, providing a space for people to reimagine the city and playing an active role as an integrative public space, the paper argues that there are reasons to be skeptical about the long-term goals the pop-up landscapes serve, given the widespread focus on real estate-led development.     

Low densities of sea urchins influence the structure of algal assemblages in the western Mediterranean

Numerous studies of interactions between urchins and algae in temperate areas have shown an important structuring effect of sea urchin populations. These studies focused almost wholly on the effect of high urchin densities on laminarian forests. In contrast, algal communities below 5–6 m depth in the northwestern Mediterranean are characterised by low sea urchin densities (<5 ind m⁻²) and the absence of laminarian forests. No previous research has addressed sea urchin/algal interactions in this type of community. To determine the effect of the most abundant echinoid species, Paracentrotus lividus, on well-established algal communities in this area, we performed a removal–reintroduction experiment in rocky patches located between 13 and 16 m depth in the northwestern Mediterranean, where sea urchin densities ranged between 0.9 and 3.4 ind m⁻². After 6 months, the cover of non-crustose algae was significantly higher in the plots from which sea urchins had been removed than in control plots (84 vs 67% cover). These removal plots reverted to their original state upon reintroduction of sea urchins. The non-crustose algae consisted of turfing and frondose forms, with the former representing some 70% of the non-crustose algal cover. Change in the cover of turfing algae was responsible for the significant increase in algal development in the sea urchin removal plots. The response of frondose algae to the treatment varied between algal species. It is concluded that grazing by P. lividus exerts a significant effect on habitat structure, even in communities with low sea urchin densities, such as those found in vast areas of the Mediterranean sublittoral.     

Climate change mitigation strategies for agriculture: an analysis of nationally determined contributions,biennial reports and biennial update reports

The role of agriculture in the context of climate change is a complex issue. On the one hand, concerns about food security highlight the need to prioritize adaptation; on the other hand, the target of the Paris Agreement (keeping global temperature rise well below 2°C) cannot be achieved without a significant decrease in agricultural emissions. Various analyses of nationally determined contributions (NDCs) submitted under the Paris Agreement show how countries intend to prioritize the needs for adaptation and mitigation in the agricultural sector. This paper focuses on 46 countries that contribute 90% of global agricultural emissions and asks how they are addressing the agricultural sector in their climate mitigation policies. It takes into account that conditions and circumstances in countries vary significantly but might also indicate similar patterns. The analysis is based on information provided by countries in their NDCs, as well as their Biennial Reports (BRs) or Biennial Update Reports (BURs) under the UN Framework Convention on Climate Change (UNFCCC). It further includes data on national agricultural emissions. By applying a mixed methods approach, which combines qualitative content analysis and comparative cluster analysis, we find that countries vary in their progress on agriculture and climate mitigation for many different reasons. These reasons include the national perception of the problem, divergent starting points for climate policy, particularities of the agricultural sector and, correspondingly, the availability of cost-effective mitigation technologies.

Key policy insights

• While for many countries the NDCs signify the beginning of their climate policy, UNFCCC biennial reports can be used to learn more about the policies that countries have already implemented.

• Mitigation action in the agricultural sector is emphasized most prominently in cases where co-benefits are possible and production is not impacted negatively.

• Policies and measures in the agricultural sector often do not align with the UNFCCC system of monitoring, reporting and verification (MRV). In addition to improving MRV-systems, it seems equally important to exchange national experiences with implemented measures and policies.

• The Koronivia Joint Work on Agriculture could take into account the problem of different definitions of sector boundaries and thus the importance of different mitigation measures.

     

Evaluation of forecast strategies for seasonal and decadal forecasts in presence of systematic model errors

This study discusses and compares three different strategies used to deal with model error in seasonal and decadal forecasts. The strategies discussed are the so-called full initialisation, anomaly initialisation and flux correction. In the full initialisation the coupled model is initialised to a state close to the real-world attractor and after initialisation the model drifts towards its own attractor, giving rise to model bias. The anomaly initialisation aims to initialise the model close to its own attractor, by initialising only the anomalies. The flux correction strategy aims to keep the model trajectory close to the real-world attractor by adding empirical corrections. These three strategies have been implemented in the ECMWF coupled model, and are evaluated at seasonal and decadal time-scales. The practical implications of the different strategies are also discussed. Results show that full initialisation results in a clear model drift towards a colder climate. The anomaly initialisation is able to reduce the drift, by initialising around the model mean state. However, the erroneous model mean state results in degraded seasonal forecast skill. The best results on the seasonal time-scale are obtained using momentum-flux correction, mainly because it avoids the positive feedback responsible for a strong cold bias in the tropical Pacific. It is likely that these results are model dependent: the coupled model used here shows a strong cold bias in the Central Pacific, resulting from a positive coupled feedback between winds and SST. At decadal time-scales it is difficult to determine whether any of the strategies is superior to the others.     

Multi-stage volcanic events: A statistical investigation

Volcanic events comprising multiple eruptive stages are common in the historical and geological record and display activity of variable intensity ranging, in some cases, through to several centuries. To better understand the characteristics of such events globally, this study explores a database of historical events having Volcanic Explosivity Indices 4 or greater. The database was compiled for the most part from published and unpublished material provided by the Smithsonian Institution. The database was examined to find common statistical relationships, within and between the variables characterising multi-stage explosive events.     

Geochemical pattern classification of recent volcanic products from Mt. Etna, Italy, based on Kohonen maps and fuzzy clustering

We present the application of a classification method based on Kohonen maps and fuzzy clustering to geochemical analyses of volcanic products erupted on Mt. Etna from 1995 to 2005. Based on 13 major and trace elements, the classification allows a new way to visualize distinct compositional features of magma both considering long period as well as single eruptive events, such as in 2001 and 2002–03 flank eruptions. Products of the various vents do not necessarily form homogeneous groups, but show clear trends of chemical evolution with time. Using a convenient color code, the graphical visualization of the results in just a single picture allows the rapid identification of the compositional features of each sample and their comparison with all the products analyzed in the 10-year-long time span. This single picture accounts for the mutual interactions of the 13 components avoiding shortcomings of classical low-dimensional plots where components relevant for the discrimination have to be found in a priori study of many diagrams. On the basis of the synoptic information provided by pattern classification, we identify links between the products of different eruptive vents which deliver a reliable picture of a multifaceted plumbing system, in agreement with geochemical and geophysical evidence reported in literature. The analysis of the 13-dimensional data set using the Kohonen maps and fuzzy clustering simultaneously turned out to be straightforward and easy. Accordingly, the results of this application will be useful also as a contextual data set for new data in future ongoing eruptive episodes.     

Relational Hubs for Collaborative Landscape Stewardship

Abstract

Landscape stewardship is considered an important place-based approach to addressing sustainability challenges. Working at landscape-level requires collaboration between diverse landscape stakeholders. In this study, we partnered with local stewardship practitioners across six cases in South Africa to investigate how they facilitate collaboration towards social-ecological sustainability outcomes. We found that practitioners facilitate collaboration among stakeholders by operating as relational hubs in the landscape. Through these hubs, they build new inter-personal relationships among stakeholders, creating social networks which enable stewardship practice. The hubs deepen human-nature relationships by creating enabling conditions for stewards to put stewardship ethics into action. Drawing on insights from these cases, we call for a relational approach to landscape stewardship which focuses on human-to-human and human-to-nature relationships. Moreover, we argue that landscape stewardship initiatives need to re-focus stewardship on stewards, recognizing them as key agents of change in addressing the conflict between agriculture and conservation inherent in many landscapes.     

Regional ash fall hazard I: a probabilistic assessment methodology

Volcanic ash is one of the farthest-reaching volcanic hazards and ash produced by large magnitude explosive eruptions has the potential to affect communities over thousands of kilometres. Quantifying the hazard from ash fall is problematic, in part because of data limitations that make eruption characteristics uncertain but also because, given an eruption, the distribution of ash is then controlled by time and altitude-varying wind conditions. Any one location may potentially be affected by ash falls from one, or a number of, volcanoes so that volcano-specific studies may not fully capture the ash fall hazard for communities in volcanically active areas. In an attempt to deal with these uncertainties, this paper outlines a probabilistic framework for assessing ash fall hazard on a regional scale. The methodology employs stochastic simulation techniques and is based upon generic principles that could be applied to any area, but is here applied to the Asia-Pacific region. Average recurrence intervals for eruptions greater than or equal to Volcanic Explosivity Index 4 were established for 190 volcanoes in the region, based upon the eruption history of each volcano and, where data were lacking, the averaged eruptive behaviour of global analogous volcanoes. Eruption histories are drawn from the Smithsonian Institution’s Global Volcanism Program catalogue of Holocene events and unpublished data, with global analogues taken from volcanoes of the same type category: Caldera, Large Cone, Shield, Lava dome or Small Cone. Simulated are 190,000 plausible eruption scenarios, with ash dispersal for each determined using an advection–diffusion model and local wind conditions. Key uncertainties are described by probability distributions. Modelled results include the annual probability of exceeding given ash thicknesses, summed over all eruption scenarios and volcanoes. A companion paper describes the results obtained for the Asia-Pacific region     

Crystal structure and cation distribution in some natural magnetites

Summary The crystal structures of two natural magnetites were refined. Both turned out to have equipoints 8a and 16d (Fd3m) fully occupied and hence different from type I and type II defect structures investigated by Fleet (1981, 1982). It was possible to improve the cation radii for Fe²⁺ ad Fe³⁺ in octahedral and tetrahedral coordinations for pure and almost pure magnetites obtaining very good agreement between observed and calculated values of the two independent geometric structure parameters, i.e. cell edge and oxygen coordinate. The present results lead to an estimate of inversion parameter i in (Fe _1–i ²⁺ Fe _i ³⁺ )(Fe _i ²⁺ Fe _2t-i ³⁺ )O₄, of about 0.90, equal for all the four pure magnetites, independently of type of structure and also of cooling history.

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Kristallstruktur und kationverteilung von einigen natürlichen magnetiten

Zusammenfassung Die Kristallstrukturen von zwei natürlichen Magnetiten wurden verfeinert. Es stellte sich heraus, daß ihre Gitterplätze 8 a und 16d (Fd 3 m) voll besetzt sind, und sich somit von den von Fleet (1981, 1982) bestimmten Defektstrukturen unterscheiden. Die Kationradien für Fe²⁺ und Fe³⁺ in Oktaeder- und Tetraeder-Koordinationen wurden für reine und fast reine Magnetite verbessert. Dabei wurde eine gute Korrelation zwischen beobachteten und berechneten Werten der beiden unabhängigen Parameter in der Struktur, d.h. Gitterkonstante und Sauerstoff-Ortsparameter gefunden. Die vorliegenden Ergebnisse bringen einen Umkehrparameter i in (Fe _1–i ²⁺ Fe _i ³⁺ )(Fe _i ²⁺ Fe _2–i ³⁺ )O₄ von ungefähr 0.90, der in allen reinen Magnetiten gleich und unabhängig von dem Strukturtyp sowie dem Abkühlverhalten ist.

     

Normal modes of synchronous rotation

The dynamics of synchronous rotation and physical librations are revisited in order to establish a conceptually simple and general theoretical framework applicable to a variety of problems. Our motivation comes from disagreements between the results of numerical simulations and those of previous theoretical studies, and also because different theoretical studies disagree on basic features of the dynamics. We approach the problem by decomposing the orientation matrix of the body into perfectly synchronous rotation and deviation from the equilibrium state. The normal modes of the linearized equations are computed in the case of a circular satellite orbit, yielding both the periods and the eigenspaces of three librations. Libration in longitude decouples from the other two, vertical modes. There is a fast vertical mode with a period very close to the average rotational period. It corresponds to tilting the body around a horizontal axis while retaining nearly principal-axis rotation. In the inertial frame, this mode appears as nutation and free precession. The other vertical mode, a slow one, is the free wobble. The effects of the nodal precession of the orbit are investigated from the point of view of Cassini states. We test our theory using numerical simulations of the full equations of the dynamics and discuss the disagreements among our study and previous ones. The numerical simulations also reveal that in the case of eccentric orbits large departures from principal-axis rotation are possible due to a resonance between free precession and wobble. We also revisit the history of the Moon's rotational state and show that it switched from one Cassini state to another when it was at 46.2 Earth radii. This number disagrees with the value 34.2 derived in a previous study.