Fuzzy factorial analysis of snow avalanches

The mutual influence of 21 factors pertaining to terrain, weather, forest and snowpack have been discussed by 10 experts. The semantic (nil, weak, medium, high) evaluations are translated as membership degrees of fuzzy sets, and averaged between the experts by taking their fuzzy expectation value, yielding a 21 × 21 fuzzy matrix for direct interactions. Fuzzy successive multiplications and additions of the matrix give the indirect interactions. The activity and the passivity of the factors with respect to avalanches is represented by directed weighted graphs, and the average semantic values by a 4 × 4 matrix: the activity (passivity) is weak (strong) for tree damage; medium (nil) for altitude; medium (weak) for ground shape; medium (medium) for vegetation, soil, wind, microclimate, tree type, vertical distribution and mechanics of trees, snowpack distribution and snow gliding; strong (nil) for ground inclination and exposition, weather; strong (medium) for heat, precipitation, horizontal distribution of trees, snowpack constitution and stability.     

Global carbon budgets and the viability of new fossil fuel projects

Policy-makers of some fossil fuel-endowed countries wish to know if a given fossil fuel supply project is consistent with the global carbon budget that would prevent a 2 °C temperature rise. But while some studies have identified fossil fuel reserves that are inconsistent with the 2 °C carbon budget, they have not shown the effect on fossil fuel production costs and market prices. Focusing on oil, we develop an oil pricing and climate test model to which we apply future carbon prices and oil consumption from several global energy-economy-emissions models that simulate the energy supply and demand effects of the 2 °C carbon budget. Our oil price model includes key oil market attributes, notably upper and lower market share boundaries for different oil producer categories, such as OPEC. Using the distribution of the global model results as an indicator of uncertainty about future carbon prices and oil demand, we estimate the probability that a new investment of a given oil source category would be economically viable under the 2 °C carbon budget. In our case study of Canada’s oil sands, we find a less than 5% probability that oil sands investments, and therefore new oil pipelines, would be economically viable over the next three decades under the 2 °C carbon budget. Our sensitivity analysis finds that if OPEC agreed to reduce its market share to 30% by 2045, a significant reduction from its steady 40–45% of the past 25 years, then the probability of viable oil sands expansion rises to 30%.     

Assessing past changes in bioavailable zinc from a terrestrial (Zn/Si)opal record

Historical changes in bioavailable Zn concentrations of the surface waters of Lake Geneva were assessed by analyzing the zinc content of fossil diatoms. The measured ratios of Zn to Si in the opal ((Zn/Si)_opal) were consistent with both data obtained for cultured freshwater diatoms that were representative of lake Geneva and with field data. Reconstructed variations suggested that increased Zn uptake by phytoplankton occurred in the period from 1960–1980 resulting from an increased loading of Zn to the lake. Nonetheless, observed concentrations were sufficiently low that no adverse effects were expected on the pelagic community. The data presented here suggest that (Zn/Si)_opal records may become a valuable tool to assess past changes in bioavailable Zn concentrations in freshwater systems.     

Show some enthusiasm, but not too much: carbon capture and storage development prospects in China

China is the world's largest carbon dioxide (CO₂) emitter and its energy system is dominated by coal. For China to dramatically reduce its greenhouse gas (GHG) emissions over the next few decades, it must either replace most of its uses of coal with energy supplies from renewables and nuclear power or install demonstration-size and then scaled-up carbon capture and storage (CCS) technologies. Currently, China is pushing ahead with increased investment in renewables and nuclear power and with demonstration CCS projects. This strategy is consistent with a country that seeks to be ready in case global pressures prompt it to launch an aggressive GHG reduction effort while also not going so fast that it reduces the likelihood of receiving substantial financial support from wealthier countries, as it feels it is entitled to as a developing country. At such a time, given the magnitude of the coal resource in China, and the country's lack of other energy resources, it is likely the Chinese will make a substantial effort to develop CCS before taking the much more difficult step of trying to phase-out almost all use of coal in the span of just a few decades in a country that is so dependent on this domestically abundant and economically affordable resource.     

An evaluation of the performance of rock fall protection measures and their role in hazard zoning

Natural Hazards - Rock falls threaten human lives and assets in mountainous regions all over the world. Protection measures are one of the most effective solutions for mitigating rock fall-related...     

Subarctic Pacific evidence for a glacial deepening of the oceanic respired carbon pool

Measurements of benthic foraminiferal cadmium:calcium (Cd/Ca) have indicated that the glacial–interglacial change in deep North Pacific phosphate (PO₄) concentration was minimal, which has been taken by some workers as a sign that the biological pump did not store more carbon in the deep glacial ocean. Here we present sedimentary redox-sensitive trace metal records from Ocean Drilling Program (ODP) Site 882 (NW subarctic Pacific, water depth 3244 m) to make inferences about changes in deep North Pacific oxygenation – and thus respired carbon storage – over the past 150,000 yr. These observations are complemented with biogenic barium and opal measurements as indicators for past organic carbon export to separate the influences of deep-water oxygen concentration and sedimentary organic carbon respiration on the redox state of the sediment. Our results suggest that the deep subarctic Pacific water mass was depleted in oxygen during glacial maxima, though it was not anoxic. We reconcile our results with the existing benthic foraminiferal Cd/Ca by invoking a decrease in the fraction of the deep ocean nutrient inventory that was preformed, rather than remineralized. This change would have corresponded to an increase in the deep Pacific storage of respired carbon, which would have lowered atmospheric carbon dioxide (CO₂) by sequestering CO₂ away from the atmosphere and by increasing ocean alkalinity through a transient dissolution event in the deep sea. The magnitude of change in preformed nutrients suggested by the North Pacific data would have accounted for a majority of the observed decrease in glacial atmospheric pCO₂.