Scenarios for a 2 °C world: a trade-linked input–output model with high sector detail

In this study a scenario model is used to examine if foreseen technological developments are capable of reducing CO₂ emissions in 2050 to a level consistent with United Nations Framework Convention on Climate Change (UNFCCC) agreements, which aim at maximizing the temperature rise to 2 °C compared to pre-industrial levels. The model is based on a detailed global environmentally extended supply–use table (EE SUT) for the year 2000, called EXIOBASE. This global EE SUT allows calculating how the final demand in each region drives activities in production sectors, and hence related CO₂ emissions, in each region. Using this SUT framework, three scenarios have been constructed for the year 2050. The first is a business-as-usual scenario (BAU), which takes into account population, economic growth, and efficiency improvements. The second is a techno-scenario (TS), adding feasible and probable climate mitigation technologies to the BAU scenario. The third is the towards-2-degrees scenario (2DS), with a demand shift or growth reduction scenario added to the TS to create a 2 °C scenario. The emission results of the three scenarios are roughly in line with outcomes of typical scenarios from integrated assessment models. Our approach indicates that the 2 °C target seems difficult to reach with advanced CO₂ emission reduction technologies alone.

Policy relevance

The overall outlook in this scenario study is not optimistic. We show that CO₂ emissions from steel and cement production and air and sea transport will become dominant in 2050. They are difficult to reduce further. Using biofuels in air and sea transport will probably be problematic due to the fact that agricultural production largely will be needed to feed a rising global population and biofuel use for electricity production grows substantially in 2050. It seems that a more pervasive pressure towards emission reduction is required, also influencing the basic fabric of society in terms of types and volumes of energy use, materials use, and transport. Reducing envisaged growth levels, hence reducing global gross domestic product (GDP) per capita, might be one final contribution needed for moving to the 2 °C target, but is not on political agendas now.     

Climate,fire and vegetation history from subtropical North Stradbroke Island (Minjerribah), eastern Australia,during the last three interglacials

Records of Australian palaeoclimate beyond the last glacial cycle are rare, limiting detailed analysis of long-term climate trends and associated ecosystem responses. This study analyses a discontinuous pollen and charcoal record from Fern Gully Lagoon, North Stradbroke Island (Minjerribah), subtropical Queensland, Australia, which covers much of the last ~210 ,000 years. Climate variation is inferred from changes in vegetation, while analysis of micro- and macrocharcoal is used to infer fire activity. Pollen assemblages consist of ~40% rainforest taxa during marine isotope stage (MIS) 7a–c and early MIS 5. These are inferred to result from high rainfall in the Australian subtropics, which was also evident in north-east and central Australia. Human impact from 21 ,000 years ago likely supressed post-MIS 2 rainforest expansion to some extent. However, the increased Holocene abundance of herbs and grasses and reduced representation of aquatic taxa suggest that the Holocene was relatively dry when compared with early MIS 5 and MIS 7a–c. Similar MIS 5 and early MIS 7a–c climates, in contrast to a notably drier Holocene, suggest that the progressive interglacial drying trend most strongly recorded in central Australia was not a major feature of subtropical eastern Australian climates.     

Radiative transfer in the atmosphere of Venus and application to surface emissivity retrieval from VIRTIS/VEX measurements

The radiation measurements of VIRTIS-M-IR (1-5 μm) on Venus Express provide a valuable database for systematic studies of the atmosphere and surface of the Earth’s sister planet. The present paper focuses on the investigation of physical parameters that determine the retrieval accuracy of deep atmosphere and surface features of Venus including compositional conditions, continuum absorption effects, and spectroscopic input data required for radiative transfer simulations. The parameter discussion shall serve as a reference for ongoing and future work on methodical and simulation input data improvements.The high variability of the nightside atmospheric and surface emission window radiances with respect to cloud opacity and surface elevation is modeled and discussed in direct comparison with measurements performed over the northern hemisphere. Venus surface elevation is retrieved using the 1.18 and 1.02 μm emission windows where radiance ratios are well suited to de-cloud the measurement data. In general, the ratio-based VIRTIS topography is in good agreement with the Magellan topography, but differences occur in localized areas. The paper discusses possible origins of such differences including surface emissivity “anomalies”. Surface emissivity variations that may be due to changes in the chemical composition (mineralogy) and surface texture are important indicators of the nature of the surface material.Preliminary radiance retrievals along a number of complete northern orbits reveal a trend towards lower values of highland surface emissivity compared to the surrounding lowlands. Already the Magellan radar experiment suggested compositional variations at moderately high altitudes over the tesserae. They probably indicate a more felsic component giving a hint to older surface forming processes.     

Towards a Validation of Scintillometer Measurements: The LITFASS-2009 Experiment

Scintillometry has been increasingly used over the last decade for the experimental determination of area-averaged turbulent fluxes at a horizontal scale of a few kilometres. Nevertheless, a number of assumptions in the scintillometer data processing and interpretation still call for a thorough evaluation, in particular over heterogeneous terrain. Moreover, a validation of the path-averaged structure parameters derived from scintillometer data (and forming the basis for the flux calculations) by independent measurements is still missing. To achieve this, the LITFASS-2009 field campaign has been performed around the Meteorological Observatory Lindenberg ?C Richard-A?mann-Observatory of the German Meteorological Service (DWD) in July 2009. The experiment combined tower-based in-situ turbulence measurements, field-scale laser scintillometers, long-range optical (large-aperture) and microwave scintillometers, and airborne turbulence measurements using an automatically operating unmanned aircraft. The paper describes the project design and strategy, and discusses first results. Daytime near-surface values of the temperature structure parameter, ${C_{T}^{2}}$ , over different types of farmland differ by more than one order of magnitude in their dependence on the type and status of the vegetation. Considerable spatial variability in ${C_{T}^{2}}$ was also found along the flight legs at heights between 50 and 100?m. However, it appeared difficult to separate the effects of heterogeneity from the temporal variability of the turbulence fields. Aircraft measurements and scintillometer data agreed in magnitude with respect to the temporal variation of the path-averaged ${C_{T}^{2}}$ values during the diurnal cycle. The decrease of ${C_{T}^{2}}$ with height found from the scintillometer measurements close to the surface and at 43?m under daytime convective conditions corresponds to free-convection scaling, whereas the aircraft measurements at 54 and 83?m suggest a different behaviour.     

Systematic study of universal‐stage measurements of planar deformation features in shocked quartz: Implications for statistical significance and representation of results

Abstract— The presence of shocked quartz is one of the key lines of evidence for the impact origin of rocks. Crystallographic orientations of planar deformation feature (PDF) sets in shocked quartz have been used to constrain the peak shock pressure that these grains have experienced. So far no systematic and comparative studies of the various orientation measurement methods and their biases are available. Therefore, three shocked‐quartz‐bearing thin sections from a meta‐greywacke clast in breccia, a biotite‐gneiss, and a sandstone, respectively, were independently analyzed by three operators (two experienced and one inexperienced) using a four‐axis universal‐stage (U‐stage), in order to evaluate the quality, precision, repeatability, and representativeness of U‐stage measurements. Based on the indexing of PDF sets using a new version of the commonly used stereographic projection template, the study of 1751 PDF set orientations in 666 quartz grains in three different shocked rocks shows that differences in abundance and orientation of various PDF sets, as measured by the three separate operators, are rather limited. The precision of U‐stage measurements depends mainly on the number of PDF sets investigated, as the ability level of the operator (experienced versus inexperienced) is only responsible for minor deviations in the number of unindexed planes. The frequency percent of dominant PDF planes may vary by up to 20 percentage points (pp) or 81% for a given crystallographic orientation when only 25 sets are measured. When 100 PDF sets are measured, however, this deviation in dominant orientations is reduced to about 7 pp or 28%. We recommend the use of a new stereographic projection template, which plots the pole positions of five additional, commonly occurring PDF orientations, as it can allow indexing of up to 12 pp more PDF planes; these are planes that would previously be considered unindexed and potentially regarded as errors of measurement. Our results suggest that by following a strict measurement procedure, the reproducibility of U‐stage measurements is good and the results of different studies can be readily compared. However, it is critical that published PDF orientation histograms clearly define what type of frequency measurement is used, whether or not unindexed PDF sets are included in the frequency calculations, the numbers of grains and sets analyzed, and the relative proportions of each PDF set population that are combined in the histograms. This information appears to be essential for effectively comparing datasets from different studies.     

High Spectral Resolution Observation of Decimetric Radio Spikes Emitted by Solar Flares – First Results of the Phoenix-3 Spectrometer

A new multichannel spectrometer, Phoenix-3, is in operation having capabilities to observe solar flare radio emissions in the 0.1?–?5 GHz range at an unprecedented spectral resolution of 61.0 kHz with high sensitivity. The present setup for routine observations allows measuring circular polarization, but requires a data compression to 4096 frequency channels in the 1?–?5 GHz range and to a temporal resolution of 200 ms. First results are presented by means of a well observed event that included narrowband spikes at 350?–?850 MHz. Spike bandwidths are found to have a power?–?law distribution, dropping off below a value of 2 MHz for full width at half maximum (FWHM). The narrowest spikes have a FWHM bandwidth less than 0.3 MHz or 0.04% of the central frequency. The smallest half-power increase occurs within 0.104 MHz at 443.5 MHz, which is close to the predicted natural width of maser emission. The spectrum of spikes is found to be asymmetric, having an enhanced low-frequency tail. The distribution of the total spike flux is approximately an exponential.     

Late-Glacial radiocarbon- and palynostratigraphy on the Swiss Plateau

A detailed late-glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator ¹⁴C dates on terrestrial plant macrofossils. Two plateaux of constant.,¹⁴C age were observed, occurring at 12,700 B.P. and at 10,000 B.P. The consequences of these plateaux for palaeo-ecological investigations are threefold: (1) a more refined ¹⁴C dating within the plateaux is not possible, (2) in teleconnections between different sites (if based on ¹⁴C dating and concerning the periods around 12,700 B.P. and 10,000 B.P.) events are considered synchronous which are only synchronous within a plateau of constant age, and (3) exact time-depth relationship and therefore influx calculations are made impossible during these plateau periods. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones (at 13, 12, 11 and 10ka B.P.) and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Belling and at the beginning of the Younger Dryas becomes obvious.     

Geometry,bed topography and drainage system structure of the haut glacier d'Arolla,Switzerland

As part of an integrated study of the hydrology, meltwater quality and dynamics of the Haut Glacier d'Arolla, Switzerland, the glacier's drainage network structure was determined from patterns of dye recovery in 342 injection experiments conducted from 47 moulins distributed widely across the glacier. This structure was compared with theoretical predictions based upon reconstructed patterns of water flow governed by (a) the subglacial hydraulic potential surface, and (b) the subglacial bedrock surface. These reconstructions were based on measurements of ice surface and bedrock topography obtained by a combination of ground survey and radio-echo sounding techniques. The two reconstructions simulate the drainage system structures expected for (a) closed channels, in which water is pressurized by the overlying ice, and (b) gravity-driven, open-channel flow. The closed-channel model provides the best fit to the observed structure, even though theoretical calculations suggest that, under summer discharge conditions, open-channel flow may be widespread beneath the glacier. Possible reasons for this apparent discrepancy are discussed.