Integrated Assessment of Long-term Climate Policies: Part 2 – Model Results and Uncertainty Analysis

An integrated assessment model (IAM) is applied to explore optionsfor long-term climate policy by identifying permitted emissioncorridors. The options are determined under various assumptionsabout constraints related to acceptable impacts of climate changein terms of alterations induced in natural ecosystems in protectedareas and about acceptable mitigation costs, burden sharingprinciples, and implementation flexibility. The results show thatabout 25% of the protected areas worldwide will witness ecosystemtransformation in the next century even if the costs of emissionreduction are allowed to reach 2% of per-capita consumption. Anuncertainty analysis surveys the implications of modifyingselected key model variables on the existence and shape of theemission corridors. Within plausible ranges of parametervariations, the emission corridor turns out to be rather sensitiveto impact constraints, climatic constraints like the magnitude andrate of the global mean temperature increase, and to aerosolemission scenarios.     

Crustal contamination of mafic magmas: evidence from a petrological, geochemical and Sr–Nd–Os–O isotopic study of the Proterozoic Isortoq dike swarm, South Greenland

The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe–Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs in some samples as a late magmatic phase. Liquidus temperatures of olivine-bearing samples range between 1120 and 1145 °C and solidus temperatures are 850–930 °C. Calculated silica activities are highly variable between 0.53 and unity. Oxygen fugacities vary from −3 to +1 log units relative to the fayalite–magnetite–quartz buffer.

The rocks have MgO contents <6 wt.% with Mg# between 53 and 17. Primitive mantle-normalized trace element patterns show a relative enrichment of LIL elements with Ba peaks and Nb troughs. Clinopyroxenes show a general enrichment in REE relative to chondritic values with variable slightly positive to prominent negative Eu anomalies. Two of the dikes were dated with Sm–Nd three-point isochrons at 1190±44 and 1187±87 Ma, respectively. Initial ⁸⁷Sr/⁸⁶Sr ratios of mafic mineral separates range from 0.70289 to 0.70432 and initial _Nd values vary from +0.3 to −10.7. Whole-rock initial ¹⁸⁷Os/¹⁸⁸Os ratios are highly variable including very radiogenic values of up to 7.967. δ¹⁸O_v-smow values of separated clinopyroxene and amphibole range from +5.2‰ to +6.2‰ and fall within the range of typical mantle-derived rocks, although mixing with a lower crustal component is permitted by the data. Using energy-constrained assimilation-fractional crystallization (EC-AFC) modeling equations, the Sr–Nd isotope data of the more radiogenic samples can successfully be modeled by addition of up to 10% lower crustal granulite-facies Archean gneisses as contaminants. The Os isotopic data also suggest the involvement of old radiogenic crust. In accordance with seismic data, we conclude that a wedge of Archean crust extends from West Greenland further to the south below the present erosion level.     

Mars as never seen before

Images from the High Resolution Stereo Camera on Mars Express reveal the surface of the Red Planet in unprecedented detail – and should have the whole planet mapped at high resolution in just two years. Over the next six pages, Ernst Hauber and Gerhard Neukum set the scene and reveal some of the spectacular images already captured.
(All images are courtesy of ESA/DLR/FU Berlin/G Neukum unless otherwise credited.)     

Earth's free core nutation determined using C032 superconducting gravimeter at station Wuhan/China

The long series tidal gravity observations from 1997 to 2002 recorded with C032 superconducting gravimeter (SG) at station Wuhan/China are used in order to study the Earth's geodynamics. The tidal gravity parameters are determined precisely using Eterna software package after careful data pre-processing. The Earth's free core nutation (FCN) resonant parameters (eigenperiods, quality factors and resonant strengths) are determined accurately. The results show the determined eigenperiod to be 431.0 sidereal days with an accuracy of ±1.81%, the quality factor is a negative one as of −7002, and the resonance strength can be explained by the elastic property of the Earth's mantle. The discrepancy of the eigenperiods when using various ocean models can amount to ±1.8%. The 30 sidereal days difference between the determined eigenperiod in this paper and the one in theoretical computation given by Wahr and Bergen can be explained by the real dynamic ellipticity of the Earth's liquid core, i.e., it is about 5% larger than the one under the hydrostatic equilibrium assumption.     

Tests of phase center variations of various GPS antennas, and some results

Phase variations of GPS receiving antennas are a significant error component in precise GPS applications. A calibration procedure has been developed by Geo++ and the Institut für Erdmessung, which directly determines absolute phase center variations (PCVs) without any multipath influence by field measurements. The precision and resolution of the procedure allows the determination of reliable azimuthal variations. PCV may affect long-term static GPS differently than real-time GPS, depending on the applications. At the same time, different antenna types are involved. Less investigations have been done on absolute PCV of rover antennas than on geodetic antennas which, however, becomes more important due to the mixed antenna situation in GPS reference networks and RTK networks. The concepts of the absolute PCV field calibration are summarized and emphasis is placed on a variety of absolute PCV patterns of geodetic and rover antennas. Electronic Publication     

Sweden

Four invertebrate and one fish species (Cerastoderma edule, Mya arenaria, Arenicola marina, Crangon crangon, Solea solea) from a single area of the German Wadden sea were investigated for concentrations of ten organochlorine pollutants in 1976. PCB concentrations (wet tissue basis) were predominating with 10–200 ng g^?1, while p,p′-DDD, dieldrin, α-HCH, γ-HCH and p,p′-DDE generally ranged between 1 and 10 ng g^?1. Values of α-endosulfan were even lower; p,p′-DDT, endrin and heptachlor epoxide could not be detected. Residue levels in shrimps were close to the lower range of values which have been found in this species from other areas of the North Sea since 1974. The patterns of residue concentrations in the five aquatic species were remarkably different indicating species- and compound-specific bioaccumulation. Trophic level and lipid content were shown to be responsible for PCB concentrations increasing from bivalves to fish.