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- ItemMid- and long-term climate projections for fragmented and delayed-action scenarios(Amsterdam [u.a.] : Elsevier Science, 2013) Schaeffer, Michiel; Gohar, Laila; Kriegler, Elmar; Lowe, Jason; Riahi, Keywan; van Vuuren, DetlefThis paper explores the climate consequences of “delayed near-term action” and “staged accession” scenarios for limiting warming below 2 °C. The stabilization of greenhouse gas concentrations at low levels requires a large-scale transformation of the energy system. Depending on policy choices, there are alternative pathways to reach this objective. An “optimal” path, as emerging from energy-economic modeling, implies immediate action with stringent emission reductions, while the currently proposed international policies translate into reduction delays and higher near-term emissions. In our delayed action scenarios, low stabilization levels need thus to be reached from comparatively high 2030 emission levels. Negative consequences are higher economic cost as explored in accompanying papers and significantly higher mid-term warming, as indicated by a rate of warming 50% higher by the 2040s. By contrast, both mid- and long-term warming are significantly higher in another class of scenarios of staged accession that lets some regions embark on emission reductions, while others follow later, with conservation of carbon-price pathways comparable to the optimal scenarios. Not only is mid-term warming higher in staged accession cases, but the probability to exceed 2 °C in the 21st century increases by a factor of 1.5.
- ItemMaking or breaking climate targets: The AMPERE study on staged accession scenarios for climate policy(Amsterdam [u.a.] : Elsevier Science, 2014) Kriegler, Elmar; Riahi, Keywan; Bauer, Nico; Schwanitz, Valeria Jana; Petermann, Nils; Bosetti, Valentina; Marcucci, Adriana; Otto, Sander; Paroussos, Leonidas; Rao, Shilpa; Currás, Tabaré Arroyo; Ashina, Shuichi; Bollen, Johannes; Eom, Jiyong; Hamdi-Cherif, Meriem; Longden, Thomas; Kitous, Alban; Méjean, Aurélie; Sano, Fuminori; Schaeffer, Michiel; Wada, Kenichi; Capros, Pantelis; van Vuuren, Detlef P.; Edenhofer, OttmarThis study explores a situation of staged accession to a global climate policy regime from the current situation of regionally fragmented and moderate climate action. The analysis is based on scenarios in which a front runner coalition – the EU or the EU and China – embarks on immediate ambitious climate action while the rest of the world makes a transition to a global climate regime between 2030 and 2050. We assume that the ensuing regime involves strong mitigation efforts but does not require late joiners to compensate for their initially higher emissions. Thus, climate targets are relaxed, and although staged accession can achieve significant reductions of global warming, the resulting climate outcome is unlikely to be consistent with the goal of limiting global warming to 2 degrees. The addition of China to the front runner coalition can reduce pre-2050 excess emissions by 20–30%, increasing the likelihood of staying below 2 degrees. Not accounting for potential co-benefits, the cost of front runner action is found to be lower for the EU than for China. Regions that delay their accession to the climate regime face a trade-off between reduced short term costs and higher transitional requirements due to larger carbon lock-ins and more rapidly increasing carbon prices during the accession period.
- ItemThe impact of the covid-19 pandemic on theworking conditions, employment, career development and well-being of refugee researchers(Basel : MDPI, 2021) Tzoraki, Ourania; Dimitrova, Svetlana; Barzakov, Marin; Yaseen, Saad; Gavalas, Vasilis; Harb, Hani; Haidari, Abas; Cahill, Brian P.; Ćulibrk, Alexandra; Nikolarea, Ekaterini; Andrianopulu, Eleni; Trajanovic, MiroslavThe ongoing ‘refugee crisis’ of the past years has led to the migration of refugee researchers (RRs) to European countries. Due to the COVID-19 pandemic, RRs often had to work from home and/or to continue their social, cultural and economic integration process under new conditions. An online survey carried out to explore the impact of the pandemic on the refugee researchers showed that RRs found it difficult to adapt their everyday working life to the ‘home’ setting. The majority have had neither a suitable work environment at home nor the appropriate technology. Although they stated that they are rather pleased with the measures taken by the public authorities, they expressed concern about their vulnerability due to their precarious contracts and the bureaucratic asylum procedures, as the pandemic has had a negative impact on these major issues. The majority of RRs working in academia seem not to have been affected at all as far as their income is concerned, while the majority of those employed in other sectors became unemployed during the pandemic (58%). Recommendations are provided to the public authorities and policy makers to assist RRs to mitigate the consequences of the pandemic on their life.
- ItemDiagnostic indicators for integrated assessment models of climate policy(Amsterdam [u.a.] : Elsevier Science, 2014) Kriegler, Elmar; Petermann, Nils; Krey, Volker; Schwanitz, Valeria Jana; Luderer, Gunnar; Ashina, Shuichi; Bosetti, Valentina; Eom, Jiyong; Kitous, Alban; Méjean, Aurélie; Paroussos, Leonidas; Sano, Fuminori; Turton, Hal; Wilson, Charlie; Van Vuuren, Detlef P.Integrated assessments of how climate policy interacts with energy-economy systems can be performed by a variety of models with different functional structures. In order to provide insights into why results differ between models, this article proposes a diagnostic scheme that can be applied to a wide range of models. Diagnostics can uncover patterns of model behavior and indicate how results differ between model types. Such insights are informative since model behavior can have a significant impact on projections of climate change mitigation costs and other policy-relevant information. The authors propose diagnostic indicators to characterize model responses to carbon price signals and test these in a diagnostic study of 11 global models. Indicators describe the magnitude of emission abatement and the associated costs relative to a harmonized baseline, the relative changes in carbon intensity and energy intensity, and the extent of transformation in the energy system. This study shows a correlation among indicators suggesting that models can be classified into groups based on common patterns of behavior in response to carbon pricing. Such a classification can help to explain variations among policy-relevant model results.
- ItemThe impact of near-term climate policy choices on technology and emission transition pathways(Amsterdam [u.a.] : Elsevier Science, 2013) Eom, Jiyong; Edmonds, Jae; Krey, Volker; Johnson, Nils; Longden, Thomas; Luderer, Gunnar; Riahi, Keywan; Van Vuuren, Detlef P.This paper explores the implications of delays (to 2030) in implementing optimal policies for long-term transition pathways to limit climate forcing to 450 ppm CO2e on the basis of the AMPERE Work Package 2 model comparison study. The paper highlights the critical importance of the period 2030–2050 for ambitious mitigation strategies. In this period, the most rapid shift to low greenhouse gas emitting technology occurs. In the delayed response emission mitigation scenarios, an even faster transition rate in this period is required to compensate for the additional emissions before 2030. Our physical deployment measures indicate that the availability of CCS technology could play a critical role in facilitating the attainment of ambitious mitigation goals. Without CCS, deployment of other mitigation technologies would become extremely high in the 2030–2050 period. Yet the presence of CCS greatly alleviates the challenges to the transition particularly after the delayed climate policies, lowering the risk that the long-term goal becomes unattainable. The results also highlight the important role of bioenergy with CO2 capture and storage (BECCS), which facilitates energy production with negative carbon emissions. If BECCS is available, transition pathways exceed the emission budget in the mid-term, removing the excess with BECCS in the long term. Excluding either BE or CCS from the technology portfolio implies that emission reductions need to take place much earlier.
- ItemIntroduction to the AMPERE model intercomparison studies on the economics of climate stabilization(Amsterdam [u.a.] : Elsevier Science, 2014) Kriegler, Elmar; Riahi, Keywan; Bosetti, Valentina; Capros, Pantelis; Petermann, Nils; van Vuuren, Detlef P.; Weyant, John P.; Edenhofer, Ottmar[No abstract available]
- ItemClimate change, agriculture, and economic development in Ethiopia(Basel : MDPI AG, 2018) Yalew, A.W.; Hirte, G.; Lotze-Campen, H.; Tscharaktschiew, S.Quantifying the economic effects of climate change is a crucial step for planning adaptation in developing countries. This study assesses the economy-wide and regional effects of climate change-induced productivity and labor supply shocks in Ethiopian agriculture. We pursue a structural approach that blends biophysical and economic models. We consider different crop yield projections and add a regionalization to the country-wide CGE results. The study shows, in the worst case scenario, the effects on country-wide GDP may add up to -8%. The effects on regional value-added GDP are uneven and range from -10% to +2.5%. However, plausible cost-free exogenous structural change scenarios in labor skills and marketing margins may offset about 20-30% of these general equilibrium effects. As such, the ongoing structural transformation in the country may underpin the resilience of the economy to climate change. This can be regarded as a co-benefit of structural change in the country. Nevertheless, given the role of the sector in the current economic structure and the potency of the projected biophysical impacts, adaptation in agriculture is imperative. Otherwise, climate change may make rural livelihoods unpredictable and strain the country's economic progress.
- ItemCoal fly ash: Linking immersion freezing behavior and physicochemical particle properties(Göttingen : Copernicus GmbH, 2018) Grawe, S.; Augustin-Bauditz, S.; Clemen, H.-C.; Ebert, M.; Eriksen Hammer, S.; Lubitz, J.; Reicher, N.; Rudich, Y.; Schneider, J.; Staacke, R.; Stratmann, F.; Welti, A.; Wex, H.To date, only a few studies have investigated the potential of coal fly ash particles to trigger heterogeneous ice nucleation in cloud droplets. The presented measurements aim at expanding the sparse dataset and improving process understanding of how physicochemical particle properties can influence the freezing behavior of coal fly ash particles immersed in water. Firstly, immersion freezing measurements were performed with two single particle techniques, i.e., the Leipzig Aerosol Cloud Interaction Simulator (LACIS) and the SPectrometer for Ice Nuclei (SPIN). The effect of suspension time on the efficiency of the coal fly ash particles when immersed in a cloud droplet is analyzed based on the different residence times of the two instruments and employing both dry and wet particle generation. Secondly, two cold-stage setups, one using microliter sized droplets (Leipzig Ice Nucleation Array) and one using nanoliter sized droplets (WeIzmann Supercooled Droplets Observation on Microarray setup) were applied. We found that coal fly ash particles are comparable to mineral dust in their immersion freezing behavior when being dry generated. However, a significant decrease in immersion freezing efficiency was observed during experiments with wet-generated particles in LACIS and SPIN. The efficiency of wet-generated particles is in agreement with the cold-stage measurements. In order to understand the reason behind the deactivation, a series of chemical composition, morphology, and crystallography analyses (single particle mass spectrometry, scanning electron microscopy coupled with energy dispersive X-ray microanalysis, X-ray diffraction analysis) were performed with dry- and wet-generated particles. From these investigations, we conclude that anhydrous CaSO4 and CaO - which, if investigated in pure form, show the same qualitative immersion freezing behavior as observed for dry-generated coal fly ash particles - contribute to triggering heterogeneous ice nucleation at the particle-water interface. The observed deactivation in contact with water is related to changes in the particle surface properties which are potentially caused by hydration of CaSO4 and CaO. The contribution of coal fly ash to the ambient population of ice-nucleating particles therefore depends on whether and for how long particles are immersed in cloud droplets.
- ItemWildfires as a source of airborne mineral dust - Revisiting a conceptual model using large-eddy simulation (LES)(Göttingen : Copernicus GmbH, 2018) Wagner, R.; Jähn, M.; Schepanski, K.Airborne mineral dust is a key player in the Earth system and shows manifold impacts on atmospheric properties such as the radiation budget and cloud microphysics. Investigations of smoke plumes originating from wildfires found significant fractions of mineral dust within these plumes - most likely raised by strong, turbulent fire-related winds. This study presents and revisits a conceptual model describing the emission of mineral dust particles during wildfires. This is achieved by means of high-resolution large-eddy simulation (LES), conducted with the All Scale Atmospheric Model (ASAM). The impact of (a) different fire properties representing idealized grassland and shrubland fires, (b) different ambient wind conditions modulated by the fire's energy flux, and (c) the wind's capability to mobilize mineral dust particles was investigated. Results from this study illustrate that the energy release of the fire leads to a significant increase in near-surface wind speed, which consequently enhances the dust uplift potential. This is in particular the case within the fire area where vegetation can be assumed to be widely removed and uncovered soil is prone to wind erosion. The dust uplift potential is very sensitive to fire properties, such as fire size, shape, and intensity, but also depends on the ambient wind velocity. Although measurements already showed the importance of wildfires for dust emissions, pyro-convection is so far neglected as a dust emission process in atmosphere-aerosol models. The results presented in this study can be seen as the first step towards a systematic parameterization representing the connection between typical fire properties and related dust emissions.
- ItemShip-borne aerosol profiling with lidar over the Atlantic Ocean: From pure marine conditions to complex dust-smoke mixtures(Göttingen : Copernicus GmbH, 2018) Bohlmann, S.; Baars, H.; Radenz, M.; Engelmann, R.; Macke, A.The multi-wavelength Raman lidar PollyXT has been regularly operated aboard the research vessel Polarstern on expeditions across the Atlantic Ocean from north to south and vice versa. The lidar measurements of the RV Polarstern cruises PS95 from Bremerhaven, Germany, to Cape Town, Republic of South Africa (November 2015), and PS98 from Punta Arenas, Chile, to Bremerhaven, Germany (April/May 2016), are presented and analysed in detail. The latest set-up of PollyXT allows improved coverage of the marine boundary layer (MBL) due to an additional near-range receiver. Three case studies provide an overview of the aerosol detected over the Atlantic Ocean. In the first case, marine conditions were observed near South Africa on the autumn cruise PS95. Values of optical properties (depolarisation ratios close to zero, lidar ratios of 23 sr at 355 and 532 nm) within the MBL indicate pure marine aerosol. A layer of dried marine aerosol, indicated by an increase of the particle depolarisation ratio to about 10% at 355 nm (9% at 532 nm) and thus confirming the non-sphericity of these particles, could be detected on top of the MBL. On the same cruise, an almost pure Saharan dust plume was observed near the Canary Islands, presented in the second case. The third case deals with several layers of Saharan dust partly mixed with biomass-burning smoke measured on PS98 near the Cabo Verde islands. While the MBL was partly mixed with dust in the pure Saharan dust case, an almost marine MBL was observed in the third case. A statistical analysis showed latitudinal differences in the optical properties within the MBL, caused by the downmixing of dust in the tropics and anthropogenic influences in the northern latitudes, whereas the optical properties of the MBL in the Southern Hemisphere correlate with typical marine values. The particle depolarisation ratio of dried marine layers ranged between 4 and 9% at 532 nm. Night measurements from PS95 and PS98 were used to illustrate the potential of aerosol classification using lidar ratio, particle depolarisation ratio at 355 and 532 nm, and Angström exponent. Lidar ratio and particle depolarisation ratio have been found to be the main indicator for particle type, whereas the Ångström exponent is rather variable.