Ecological sensitivity: a biospheric view of climate change

Climate change is often characterized in terms of climate sensitivity, the globally averaged temperature rise associated with a doubling of the atmospheric CO2 (equivalent) concentration. In this study, we develop and apply two new ecological sensitivity metrics, analogs of climate sensitivity, to investigate the potential degree of plant community changes over the next three centuries. We use ten climate simulations from the Intergovernmental Panel on Climate Change Fourth Assessment Report, with climate sensitivities from 2–4°C. The concept of climate sensitivity depends upon the continuous nature of the temperature field across the Earth’s surface. For this research, the bridge between climate change and biospheric change predictions is provided by the Equilibrium Vegetation Ecology model (EVE), which simulates a continuous description of the Earth’s terrestrial plant communities as a function of climate. The ecosensitivity metrics applied to the results of EVE simulations at the end of the twenty-first century result in 49% of the Earth’s land surface area undergoing plant community changes and 37% of the world’s terrestrial ecosystems undergoing biome-scale changes. EVE is an equilibrium model, and, although rates of ecological change are not addressed, the resultant ecological sensitivity projections provide an estimate of the degree of species turnover that must occur for ecosystems to be in equilibrium with local climates. Regardless of equilibrium timescales, the new metrics highlight the Earth’s degree of ecological sensitivity while identifying ecological “hotspots” in the terrestrial biosphere’s response to projected climate changes over the next three centuries

Late Cretaceous Climate, Vegetation, and Ocean Interactions

The Campanian age of the Late Cretaceous was warm, with no evidence for permanent or seasonal sea ice at high latitudes. Sea level was high, creating extensive epicontinental and shallow shelf seas. Very low meridional thermal gradients existed in the oceans and on land. Campanian (80 Ma) climate and vegetation have been simulated using GENESIS (Global ENvironmental and Ecological Simulation of Interactive Systems) Version 2.0 and EVE (Equilibrium Vegetation Ecology model), developed by the Climate Change Research section of the Climate and Global Dynamics division at NCAR (National Center for Atmospheric Research). GENESIS is a comprehensive Earth system model, requiring high resolution (2^circ by 2^circ) solid earth boundary condition data as input for paleoclimate simulations. Boundary condition data define certain prescribed global fields such as the distribution of land-sea-ice, topography, orographic roughness, and soil texture, as well as atmospheric chemistry, the solar constant, and orbital parameters that define the latitudinal distribution of solar insolation. A comprehensive, high resolution paleogeography has been reconstructed for the Campanian. The paleogeography, based on a new global plate tectonic model, provides the framework for the solid earth boundary conditions used in the paleoclimate simulation. Because terrestrial ecosystems influence global climate by affecting the exchange of energy, water and momentum between the land surface and the atmosphere, the distribution of global vegetation should be included in pre-Quaternary paleoclimate simulations. However, reconstructing global vegetation distributions from the fossil record is difficult. EVE predicts the equilibrium state of plant community structure as a function of climate and fundamental ecological principles. The model has been modified to reproduce a vegetation distribution based on life forms that existed in the Late Cretaceous. EVE has been applied as a fully interactive component of the Campanian simulation. 1500 ppm CO_2 and a QFACTOR of 4 were sufficient to maintain forest over Antarctica and high northern latitudes. The QFACTOR is the multiplicative of the oceanic heat diffusion coefficient in the slab-mixed layer ocean component of GENESIS. The simulated Campanian oceanic heat transport has maximum values of about 1.7 times 10^{15} W at 25 ^circ north and 2.6 times 10^{15} W at 25^ circ south, similar to present day observed values. Late Cretaceous forests played an important role in the maintenance of low meridional thermal gradients, polar warmth, and equable continental interiors. The Campanian high to polar latitude forests decreased surface albedo (especially in late winter-early spring, prior to snow melt), and increased net radiation and fluxes of sensible and latent heat. This warmed the high latitude troposphere and increased atmospheric moisture. The warmer atmospheric temperatures reduced winter cooling of the high latitude sea surface and aided the advection of warm, moist air from the oceans into the continental interiors

Ultrasonic Characterization of Fatigue Behavior in Metal-Matrix Composites

In the past decades, the incorporation of ceramic reinforcement in metal-matrix composites (MMC’s) brought about considerable improvements in elastic modulus, strength, wear resistance, structural efficiency, reliability and control of physical properties (e.g. density and coefficient of thermal expansion) thereby providing for improved mechanical performance in comparison to the unreinforced matrix [1–4]. S-N curves for materials such as steels are available elsewhere [5–6] whereas are limited for MMC’s. Studies on the elastic constants behavior for MMC’s as a function of temperature, volume fractions of reinforcement and applied stresses had already been conducted [7–8]. However, the fatigue behavior of elastic constants in MMC’s is not well understood. Further, the trend now is aimed at nondestructive evaluation (NDE) of materials which in the past years gained significant attention over the conventional destructive tests since the former is capable of determining the usefulness, serviceability or quality of a part or material without limiting its usefulness, which is not possible in the latter’s case [9–10]. In view of the above discussion, a result of the study on the fatigue behavior and ultrasonic characterization of monolithic aluminum and aluminum MMC’s will be discussed here

Ecological sensitivity: a biospheric view of climate change

Climate change is often characterized in terms of climate sensitivity, the globally averaged temperature rise associated with a doubling of the atmospheric CO2 (equivalent) concentration. In this study, we develop and apply two new ecological sensitivity metrics, analogs of climate sensitivity, to investigate the potential degree of plant community changes over the next three centuries. We use ten climate simulations from the Intergovernmental Panel on Climate Change Fourth Assessment Report, with climate sensitivities from 2–4°C. The concept of climate sensitivity depends upon the continuous nature of the temperature field across the Earth’s surface. For this research, the bridge between climate change and biospheric change predictions is provided by the Equilibrium Vegetation Ecology model (EVE), which simulates a continuous description of the Earth’s terrestrial plant communities as a function of climate. The ecosensitivity metrics applied to the results of EVE simulations at the end of the twenty-first century result in 49% of the Earth’s land surface area undergoing plant community changes and 37% of the world’s terrestrial ecosystems undergoing biome-scale changes. EVE is an equilibrium model, and, although rates of ecological change are not addressed, the resultant ecological sensitivity projections provide an estimate of the degree of species turnover that must occur for ecosystems to be in equilibrium with local climates. Regardless of equilibrium timescales, the new metrics highlight the Earth’s degree of ecological sensitivity while identifying ecological “hotspots” in the terrestrial biosphere’s response to projected climate changes over the next three centuries

Conservation status of freshwater mussels in Europe: state of the art and future challenges

Freshwater mussels of the Order Unionida provide important ecosystem functions and services, yet many of their populations are in decline. We comprehensively review the status of the 16 currently recognized species in Europe, collating for the first time their life-history traits, distribution, conservation status, habitat preferences, and main threats in order to suggest future management actions. In northern, central, and eastern Europe, a relatively homogeneous species composition is found in most basins. In southern Europe, despite the lower species richness, spatially restricted species make these basins a high conservation priority. Information on freshwater mussels in Europe is unevenly distributed with considerable differences in data quality and quantity among countries and species. To make conservation more effective in the future, we suggest greater international cooperation using standardized protocols and methods to monitor and manage European freshwater mussel diversity. Such an approach will not only help conserve this vulnerable group but also, through the protection of these important organisms, will offer wider benefits to freshwater ecosystems. © 2016 Cambridge Philosophical Societ