Changes in climate extremes and their impacts on the natural physical environment: An overview of the IPCC SREX report

In this volume John Murray investigates the ecological processes that control the distribution, abundance, and species diversity of benthic foraminifera in environments ranging from marsh to the deepest ocean. To interpret the fossil record it is necessary to have an understanding of the ecology of modern foraminifera and the processes operating after death leading to burial and fossilisation. This book presents the ecological background required to explain how fossil forms are used in dating rocks and reconstructing past environmental features including changes of sea level. It demonstrates how living foraminifera can be used to monitor modern-day environmental change. Ecology and Applications of Benthic Foraminifera presents a comprehensive and global coverage of the subject using all the available literature. It is supported by a website hosting a large database of additional ecological information (www.cambridge.org/0521828392) and will form an important reference for academic researchers and graduate students in Earth and Environmental Sciences.

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Ecology and Applications of Benthic Foraminifera

Porphyroclasts of feldspar and other relatively rigid minerals in mylonites commonly have mantles of dynamically recrystallized material that extend as tails into the matrix. The internal shape symmetry of such porphyroclasts is usually orthorhombic or monoclinic; the orientation of the porphyroclast with respect to the foliation (external symmetry) can also be described by these symmetry classes. An identical monoclinic external symmetry of most porphyroclasts in a given sample indicates non-coaxial flow in the matrix during at least the last stages of deformation. Two classes of porphyroclast systems with monoclinic symmetry have been identified on geometrical grounds. sigma-type porphyroclasts are characterized by wedge-shaped tails of recrystallized material. Median lines of the tails lie on opposite sides of, and do not cross, a marker line drawn parallel to the mean foliation. sigma-type porphyroclasts may lie isolated in a homogeneous matrix (sigma/sub a./-type) or may be in clusters associated with shear bands or S-C mylonites (sigma/sub b/-type). delta-type porphyroclasts commonly occur in ultramylonites and have highly attenuated recrystallized tails. Median lines of the tails cross the marker line adjacent to the porphyroclast which results in an embayment of matrix material adjacent to the host grain. More complex porphyroclast systems include ellipsoidal overturned delta-types,more » complex sigma - delta types and folded porphyroclast aggregates. In all cases, the symmetry of porphyroclast aggregates with respect to the foliation can be used to accurately determine the sense of vorticity in the mylonites.« less

Porphyroclast systems as kinematic indicators

https://doc.rero.ch/record/29510/files/spe_fit.pdf

The FOBIMO (FOraminiferal BIo-MOnitoring) initiative—Towards a standardised protocol for soft-bottom benthic foraminiferal monitoring studies

The report summarizes the science of climate change and the impacts of climate change in the United States, now and in the future.

Climate Change Impacts in the United States

Confidence limits of species proportions in microfossil assemblages

Wave climate variability in the North-East Atlantic Ocean over the last six decades

Coastal hazards affect the majority of sandy shores worldwide, and are responsible for damage to, and destruction of, property and infrastructure. The research reported here presents an integrated method for defining set-back lines associated with coastal hazards on sandy shores for a 50-year period of interest. The method is based on a worst-case scenario approach, the shoreline evolutionary trend being the basis for the initial set-back line determination. Set-back lines are afterwards adjusted by incorporating changes associated with the acceleration of sea-level rise and the evaluation of the consequences (instantaneous shoreline retreat and overwash) of an extreme storm. The method considers different approaches depending on the shoreline behaviour (erosion, dynamic stability or accretion). The set-back lines as determined are plotted over rectified aerial photographs, allowing for a straight-forward interpretation of results. The method was applied to a test case within a barrier island system (Ancao Peninsula, Ria Formosa, Algarve, Portugal). This study area was chosen because it exhibits the three different types of shoreline evolution. The method easily shows the differences in erosion-related coastal hazards along the study area, being an important tool for coastal management. However, the method should be able to be refined at every 5–10 years, for a new 50-year period, by integrating new formulations based on advances in coastal science, and by including updated information and data about the areas to which the method is applied.

An integrated method for the determination of set-back lines for coastal erosion hazards on sandy shores

Microtextural characteristics of quartz grains transported and deposited by tsunamis and storms

A field experiment was carried at Culatra Beach in Algarve (Southern Portugal) to determine longshore transport rates and sand mixing depth on a steep (slope 0.11) meso-tidal beach. The experiment was undertaken over one and a half tidal cycles using sand tracers in conjunction with wave and current monitoring. Variation of mean significant wave height during the experiment was limited (0.34-0.37 m) with mean zero-up crossing periods of 5.1-5.8 sec. Mean longshore current velocities in the breaker zone reached a peak in the second tide (0.28 m sec -1 ), while they were one order of magnitude smaller during the first (0.02 m sec -1 ) and third tide (0.04 m sec -1 ). The increase in current speed was due to a moderate wind that was blowing along shore during the second tide. Average advection velocity of the tracer cloud and longshore currents showed a good correlation, leading to calculation of much larger transport rates for the second tide (1.38 X 10 -2 m 3 sec -1 ) than for the other two (0.23 X 10 -2 m 3 sec -1 ). Average depth of sand mixing of 10.6 cm in the beach face was 29% of breaking wave height and showed a marked uni-modal distribution, with maximum of 15 cm in the breaker zone. Previously published empirical formulae do not predict satisfactorily this behavior in depth of sand mixing that seems to be peculiar of steep beaches under plunging waves. Empirical formulae were used to compute theoretical longshore transport and compare it with field observations. They all underestimated measured transport rates of about one order of magnitude, thus confirming that the morphodynamics of steep beaches are characterized by relatively high sediment transport even in relatively low energy regimes.

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Rui Taborda

Papers

Confidence limits of species proportions in microfossil assemblages

Wave climate variability in the North-East Atlantic Ocean over the last six decades

An integrated method for the determination of set-back lines for coastal erosion hazards on sandy shores

Microtextural characteristics of quartz grains transported and deposited by tsunamis and storms

Field measurements of longshore sand transport and control processes on a steep meso-tidal beach in Portugal