Climate Change: Scottish Implications Scoping Study

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A comparison of two modelling studies of environmental effects on forest carbon stocks across Europe

Two modelling approaches to describing the variation in the carbon balance of forests in different parts of Europe are presented. A forest growth model (Eurobiota) was parameterised for 3 eco-climatic zones. The parameter values were derived from process-based forest growth models developed to describe the situation at forest locations within each zone. The model was separately run for conifers and broadleaves on a 30’ grid across Europe. Daily climate data covering the period from 1830 to the present and then projected to 2100 were used. European forests were shown to be a net sink of carbon of 0.06 Pg y–1 at present. The Boreal and Temperate zones are likely to continue at their present rate or more for the next century but the net sink in the Mediterranean zone may become smaller due to projected drier conditions. The effect of temperature using the surrogate of latitude on net ecosystem productivity is also discussed. A complex forest growth model (EFM) was parameterised for Norway spruce and Scots pine, and tested against measurements from 22 forest locations across Europe. This second model showed that the main driver of increased forest growth in the 20th century has been increased nitrogen deposition, rather than increased [CO2] or climate change, as indicated by EuroBiota. Increased growth has led to increased carbon storage in the system, but most of it in tree biomass rather than stably sequestered in recalcitrant soil organic matter. Carbon stocks were increased more in Central Europe than in Scandinavia, except for some high-fertility sites where N-deposition had little impact. The EFM model was also used to predict the effects of future environmental change, and suggested that climate change and [CO2] may become the dominant environmental drivers for forest carbon exchange. The two models thus give similar results when considering only climate change and [CO2] but EFM can in addition describe the effects of N-deposition when appropriate.Comparer les impacts de facteurs environnementaux sur les stocks de carbone des forêts européennes : deux exercices de modélisation. Cette étude présente deux approches de modélisation permettant de décrire la variabilité du bilan de carbone des forêts européennes. En premier lieu, le modèle de croissance d’arbres, Eurobiota, fut paramétré pour trois zones éco-climatiques différentes. Les valeurs des paramètres furent dérivées de modèles basés sur les processus simulant la croissance d’arbres dans chacune ces zones. Le modèle fut exécuté séparément pour les conifères et les feuillus, sur une grille de modélisation de 30’ à travers l’Europe. Une base de données climatique à échelle quotidienne fut utilisée, couvrant une période de 1830 jusqu’à maintenant, et projetée jusqu’en 2100. Cet exercice de modélisation démontre que les forêts européennes actuelles représentent un puits de carbone de 0.06 Pg an–1. Dans les zones boréales et tempérées, il est probable que ce taux d’accumulation demeure ainsi mais pourrait aussi s’accroître au siècle prochain. Cependant, dû aux conditions climatiques prévues plus arides, le puits net méditerranéen pourrait décroître. Une discussion sur les effets occasionnés par la substitution de la température par la latitude pour simuler la productivité nette est aussi présentée. En second lieu, un modèle complexe basé sur les processus (EFM) fut paramétré pour l’épicéa (Norway spruce) et le pin sylvestre (Scots pine) et testé à partir de données en provenance de 22 forêts européennes. Ce dernier modèle démontre qu’au xxe siècle, le dépôt d’azote plutôt que les changements climatiques ou l’accroissement de CO2, tel que suggéré par Eurobiota, détermine principalement l’augmentation du taux de croissance des forêts. De plus, cette augmentation conduit à une accumulation de carbone dans le système se retrouvant principalement dans la biomasse des arbres plutôt que de manière stable dans la matière organique récalcitrante du sol. Les stocks de carbone de l’Europe centrale s’accroissent plus que ceux de Scandinavie, à l’exception des sites scandinaves hautement fertiles, où le dépôt d’azote influence peu la croissance. EFM fut aussi exécuté afin de prédire les impacts des changements climatiques futurs sur les échanges de carbone. Celui-ci indique que dans le futur, ce sont les changements climatiques ainsi que le CO2 qui risquent de devenir les principaux facteurs déterminant de ces échanges. Les deux modèles démontrent des résultats similaires en ce qui a trait aux changements climatiques et au CO2. Cependant, EFM permet également de décrire l’influence du dépôt d’azote

Efficient 3D Frequency-domain Full-waveform Inversion of Ocean-bottom Cable Data - Application to Valhall in the Visco-ac

International audienceWe present an application of 3D VTI visco-acoustic frequency-domain full waveform inversion (FWI) based on sparse direct solver on wide-azimuth OBC data from the Valhall oil field. Mono-parameter inversion for the vertical wavespeed is applied to the hydrophone component in the 3.5-10Hz passband. Compared to reflection traveltime tomography, we show the significant resolution improvement provided by FWI in the velocity reconstruction down to the base cretaceous reflector located below the reservoir level. This improvement was achieved although the presence of gas in the overburden. The FWI models are assessed by frequency-domain and time-domain modeling. We show an excellent match between recorded and modeled monochromatic gathers up to 10Hz. Time-domain modeling highlights the fit of the main diving and reflection arrivals interpreted in the data. We discuss the pros and cons of the frequency-domain formulation of FWI in terms of computational efficiency compared to time-domain FWI. In particular, we show the efficiency of the frequency-domain approach to process a large number of shots collected by fixed-spread acquisitions with a limited number of nodes of parallel computers. Perspectives are the use of block low-rank version of the direct solver to push inversion at higher frequencies and multi-parameter reconstruction including density, attenuation and epsilon

Climate change cannot be entirely responsible for soil carbon loss observed in England and Wales, 1978-2003

We present results from modelling studies, which suggest that, at most, only about 10–20% of recently observed soil carbon losses in England and Wales could possibly be attributable to climate warming. Further, we present reasons why the actual losses of SOC from organic soils in England and Wales might be lower than those reported

Estimating changes in Scottish soil carbon stocks using ECOSSE. I. Model description and uncertainties

To predict the response of C-rich soils to external change, models are needed that accurately reflect the conditions of these soils. Estimation of Carbon in Organic Soils—Sequestration and Emissions (ECOSSE) is a model that allows simulations of soil C and N turnover in both mineral and organic soils using only the limited meteorological, land-use and soil data that is available at the national scale. Because it is able to function at field as well as national scales if appropriate input data are used, field-scale evaluations can be used to determine uncertainty in national simulations. Here we present an evaluation of the uncertainty expected in national-scale simulations of Scotland, using data from the National Soil Inventory of Scotland. This data set provides measurements of C change for the range of soils, climates and land-use types found across Scotland. The simulated values show a high degree of association with the measurements in both total C and change in C content of the soil. Over all sites where land-use change occurred, the average deviation between the simulated and measured values of percentage change in soil C was less than the experimental error (11% simulation error, 53% measurement error). This suggests that the uncertainty in the national-scale simulations will be ~11%. Only a small bias in the simulations was observed compared to the measured values, suggesting that a small underestimate of the change in soil C should be expected at the national scale (–4%

When it pays to be friendly: employment relationships and emotional labour in hairstyling

This article examines worker-client relationships in hairstyling. Data are drawn from interviews with 15 hourly-paid and 32 self-employed hairstylists and a self-administered survey. Relations of employment are found to be central to the deployment of emotional labour. Self-employed owner-operators are highly dependent on clients, rely on deep-acting, enact favours, and are prone to emotional breaking points when they fail to realise their 'congealed service'. In contrast, hourly-paid stylists perform surface acting, resist unpaid favours and experience fewer breaking points. Methodologically this article demonstrates the importance of comparative employment relations analysis (CERA) for exposing the relationship between employment structures and labour process experiences