Detection of a sulfur dioxide signal in a tree-ring record: a case study from Trail,British Columbia,Canada

Dendroecological analysis of tree-ring chronologies was used to determine radial growth responses of a western larch (Larix occidentalis Nutt.) stand to climate and ambient SO₂ exposure. A unique, 32-year long record of ambient SO₂ concentrations was exploited to estimate annual SO₂ dose with a 0.25 ppm threshold. Tree-ring data were a subset from a previous study including three control sites and one polluted site that was near the location of the SO₂ monitor. An autoregression model was employed in a stagewise procedure that first removed climate effects by autoregression on the average of the controls and then estimated a dose-response relationship by autoregression of the residuals from the first stage on SO₂ exposure. Significant growth losses from air pollution were demonstrated that were approximately equal in magnitude to the variation explained by annual fluctuations of climate.     

Shonkin Sag laccolith,Montana

A variety of rock types is developed in the Shonkin Sag laccolith, with extreme compositions represented by the porphyritic pseudoleucite-bearing chilled margin, shonkinitic in composition, and by the final differentiate, chemically a nepheline syenite. During differentiation the pyroxenes changed in composition from Ca-rich varieties through aegirine-augite to acmite; there is no evidence of an immiscibility gap between Ca-rich and Na-rich pyroxenes. Olivine compositions changed from approximately Fa₂₀ to Fa₄₀, but in marked contrast the coexisting biotites exhibit a more extensive compositional range, from annite₂₄ to annite₁₀₀; the crystal margins of annites in the most evolved rocks are manganophyllite-rich. Titanomagnetites are TiO₂-poor varieties. Arfvedsonite and melanite occur in the most evolved syenites.From mineralogical and thermodynamic data initial and final temperatures of crystallization of the various rock types have been calculated. At an estimated total vapor pressure of 310 bars, the temperature of intrusion was 985° C. Final crystallization of the laccolith took place below 700° C, and crystallization intervals for most rock types are of the order of 170° C. Over the total magmatic temperature range the activity of silica in the melt decreased from 0.13 to 0.09. Oxygen fugacity falls with temperature approximately parallel to the synthetic fayalite-magnetite-quartz oxygen buffer until olivine disappears. The crystallization of Na-rich pyroxenes does not demand an increase in the fugacity of oxygen, but rather requires that the oxygen fugacity fall less rapidly with temperature than would be the case if olivine and magnetite were present.     

The reflection spectrum of liquid sulfur: Implications for Io

The spectral reflectance from 0.38 to 0.75 μm of a column of liquid sulfur has been measured at several temperatures between the melting point (～118°C) and 173°C. Below 160°C the spectral reflectance was observed to vary reversibly as a function of temperature, independent of the previous thermal history of the column. Once the temperature exceeded 160°C, the spectrum would not change given a subsequent decrease in temperature. The spectral reflectance of the liquid-sulfur column at all temperatures was very low (10–19%). Combining this information with Voyager spectrophotometry of Jupiter's satellite Io, it is concluded that liquid sulfur at any temperature on Io's surface would be classified as a “black area” according to the standards used by the Voyager imaging team in their spectrophotometric analysis (L. Soderblom, T. V. Johnson, D. Morrison, E. Danielson, B. L. Smith, J. Veverka, A. Cook, C. Sagan, P. Kupferman, D. Pieri, J. Mosher, C. Avis, J. Gradie, and T. Clancy (1980). Geophys. Res. Lett.7, 963–966).     

Narratives of nineteenth century drought in southern Africa in different historical source types

Climatic Change - Single- to multiple-year drought episodes posed significant challenges for agrarian communities across southern Africa during the nineteenth century and hence are widely recorded...     

Taking stock of Climate Change Acts in Europe: living policy processes or symbolic gestures?

Since the UK introduced a Climate Change Act (CCA) in 2008, similar legislation has followed in a number of states, with each having a slightly different take. What unites these examples is that they all represent framework legislation that aims to facilitate climate change mitigation by creating continuous policy processes whereby mechanisms for the reduction of greenhouse gas (GHG) emissions are developed and implemented. This article is concerned with the extent to which they are living policy processes or rather symbolic gestures. We analyse seven European CCAs with regard to GHG emission reduction targets, planning/implementation mechanisms, and feedback/evaluations prescribed by the laws. These three features correspond with three aspects of climate policy integration (CPI): interpretations of CPI as a norm; CPI as a process of governing; CPI as a policy outcome. We show that CCAs address all three aspects of CPI and constitute living policy processes, although to varying extents. However, CCAs are also policy processes in that they are part of a political system, affected by political forces external to the legislation, positively and negatively.

Key policy insights

• CCAs can provide a normative basis for policymaking on climate change at the national level, especially through quantitative emission reduction targets.

• Whilst CCAs can bring some stability and predictability to policymaking on climate change (mainly because legislation is more difficult to amend or remove than policy strategies), they are still vulnerable to political developments.

• Most CCAs lack either short/medium-term (Denmark, Finland, Ireland, Sweden) or long-term (Austria) targets. Given EU Member States’ aim to decarbonise in the next three decades and the Paris Agreement's global goal of pursuing efforts to limit warming to 1.5°C, states need to find ways to guide this process. One approach could be the inclusion of short-term, medium-term and long-term targets in their CCAs.

• Since sanctioning mechanisms are lacking across all the CCAs analysed here, it is not clear what will happen if legally binding targets are not met. Just as it is difficult to imagine speed limits and speed cameras without accompanying penalties, it is hard to imagine how CCAs without sanctions can deliver decarbonization.

     

A Godunov-type Finite Volume Scheme for Meso- and Micro-scale Flows in Three Dimensions

This short note reports the extension of the f-waves approximate Riemann solver (Ahmad and Lindeman, 2007; LeVeque, 2002; Bale et al., 2002) for three-dimensional meso- and micro-scale atmospheric flows. The Riemann solver employs flux-based wave decomposition for the calculation of Godunov fluxes and does not require the explicit definition of the Roe matrix to enforce conservation. The other important feature of the Riemann solver is its ability to incorporate source term due to gravity without introducing discretization errors. The resulting finite volume scheme is second-order accurate in space and time. The finite-difference schemes currently used in atmospheric flow models are neither conservative nor able to resolve regions of sharp gradients. The finite volume scheme described in this paper is fully conservative and has the ability to resolve regions of sharp gradients without introducing spurious oscillations in the solution. The scheme shows promise in accurately resolving flows on the meso- and micro-scales and should be considered for implementation in the dynamical cores of next generation meso- and micro-scale atmospheric flow models.     

Nested circulation modelling of inter-tidal zones: details of a nesting approach incorporating moving boundaries

Nested circulation models developed to date either exclude the flooding and drying process or prohibit flooding and drying of nested boundaries; they are therefore ill-suited to the accurate modelling of inter-tidal areas. The authors have developed a nested model with moving boundaries which permits flooding and drying of both the interior domain and the nested boundaries. The model uses a novel approach to boundary formulation; ghost cells are incorporated adjacent to the nested boundary cells so that the nested boundaries operate as internal boundaries. When combined with a tailored adaptive interpolation technique, the approach facilitates a dynamic internal boundary. Details of model development are presented with particular emphasis on the treatment of the nested boundary. Results are presented for Cork Harbour, a natural coastal system with an extensive inter-tidal zone and a complex flow regime which provided a rigorous test of model performance. The nested model was found to achieve the accuracy of a high resolution single grid model for a much lower computational cost.