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- ItemCarbon leakage in a fragmented climate regime: The dynamic response of global energy markets(Amsterdam [u.a.] : Elsevier Science, 2013) Arroyo-Currás, Tabaré; Bauer, Nico; Kriegler, Elmar; Schwanitz, Valeria Jana; Luderer, Gunnar; Aboumahboub, Tino; Giannousakis, Anastasis; Hilaire, JérômeAs a global climate agreement has not yet been achieved, a variety of national climate policy agendas are being pursued in different parts of the world. Regionally fragmented climate policy regimes are prone to carbon leakage between regions, which has given rise to concerns about the environmental effectiveness of this approach. This study investigates carbon leakage through energy markets and the resulting macro-economic effects by exploring the sensitivity of leakage to the size and composition of pioneering regions that adopt ambitious climate action early on. The study uses the multi-regional energy–economy–climate model REMIND 1.5 to analyze the implications of Europe, China and the United States taking unilateral or joint early action. We find that carbon leakage is the combined effect of fossil fuel and capital market re-allocation. Leakage is limited to 15% of the emission reductions in the pioneering regions, and depends on the size and composition of the pioneering coalition and the decarbonization strategy in the energy sector. There is an incentive to delay action to avoid near-term costs, but the immediate GDP losses after acceding to a global climate regime can be higher in the case of delayed action compared to early action. We conclude that carbon leakage is not a strong counter-argument against early action by pioneers to induce other regions to adopt more stringent mitigation.
- ItemThe implications of initiating immediate climate change mitigation - A potential for co-benefits?(Amsterdam [u.a.] : Elsevier Science, 2014) Schwanitz, Valeria Jana; Longden, Thomas; Knopf, Brigitte; Capros, PantelisFragmented climate policies across parties of the United Nations Framework on Climate Change have led to the question of whether initiating significant and immediate climate change mitigation can support the achievement of other non-climate objectives. We analyze such potential co-benefits in connection with a range of mitigation efforts using results from eleven integrated assessment models. These model results suggest that an immediate mitigation of climate change coincide for Europe with an increase in energy security and a higher utilization of non-biomass renewable energy technologies. In addition, the importance of phasing out coal is highlighted with external cost estimates showing substantial health benefits consistent with the range of mitigation efforts.
- ItemSystem complexity and policy integration challenges: The Brazilian Energy- Water-Food Nexus(Amsterdam [u.a.] : Elsevier Science, 2019) Mercure, J.-F.; Paim, M.A.; Bocquillon, P.; Lindner, S.; Salas, P.; Martinelli, P.; Berchin, I.I.; de Andrade Guerra, J.B.S.O; Derani, C.; de Albuquerque Junior, C.L.; Ribeiro, J.M.P.; Knobloch, F.; Pollitt, H.; Edwards, N.R.; Holden, P.B.; Foley, A.; Schaphoff, S.; Faraco, R.A.; Vinuales, J.E.The Energy-Water-Food Nexus is one of the most complex sustainability challenges faced by the world. This is particularly true in Brazil, where insufficiently understood interactions within the Nexus are contributing to large-scale deforestation and land-use change, water and energy scarcity, and increased vulnerability to climate change. The reason is a combination of global environmental change and global economic change, putting unprecedented pressures on the Brazilian environment and ecosystems. In this paper, we identify and discuss the main Nexus challenges faced by Brazil across sectors (e.g. energy, agriculture, water) and scales (e.g. federal, state, municipal). We use four case studies to explore all nodes of the Nexus. For each, we analyse data from economic and biophysical modelling sources in combination with an overview of the legislative and policy landscape, in order to identify governance shortcomings in the context of growing challenges. We analyse the complex interdependence of developments at the global and local (Brazilian) levels, highlighting the impact of global environmental and economic change on Brazil and, conversely, that of developments in Brazil for other countries and the world. We conclude that there is a need to adjust the scientific approach to these challenges as an enabling condition for stronger science-policy bridges for sustainability policy-making. © 2019 The Author(s)
- ItemAerial river management by smart cross-border reforestation(Amsterdam [u.a.] : Elsevier Science, 2019) Weng, Wei; Costa, Luís; Lüdeke, Matthias K.B.; Zemp, Delphine C.In the face of increasing socio-economic and climatic pressures in growing cities, it is rational for managers to consider multiple approaches for securing water availability. One often disregarded option is the promotion of reforestation in source regions supplying important quantities of atmospheric moisture transported over long distances through aerial rivers, affecting water resources of a city via precipitation and runoff (‘smart reforestation’). Here we present a case demonstrating smart reforestation's potential as a water management option. Using numerical moisture back-tracking models, we identify important upwind regions contributing to the aerial river of Santa Cruz de la Sierra (Bolivia). Simulating the effect of reforestation in the identified regions, annual precipitation and runoff reception in the city was found to increase by 1.25% and 2.30% respectively, while runoff gain during the dry season reached 26.93%. Given the city's population growth scenarios, the increase of the renewable water resource by smart reforestation could cover 22–59% of the additional demand by 2030. Building on the findings, we argue for a more systematic consideration of aerial river connections between regions in reforestation and land planning for future challenges. © 2019 The Authors
- ItemWater-saving agriculture can deliver deep water cuts for China(Amsterdam [u.a.] : Elsevier Science, 2019) Huang, Guorui; Hoekstra, Arjen Y.; Krol, Maarten S.; Jägermeyr, Jonas; Galindo, Alejandro; Yu, Chaoqing; Wang, RanranChina is working hard to reconcile growing demands for freshwater with already oversubscribed renewable water resources. However, the knowledge essential for setting and achieving the intended water consumption cuts remains limited. Here we show that on-farm water management interventions such as improved irrigation and soil management practices for maize cultivation can lead to substantial water consumption reductions, by a simulated total of 28–46 % (7–14 billion m3/year) nationally, with or without the impacts of climate change. The water consumption cut is equivalent to 16–31 % of the ultimate capacity of the South-North Water Transfer Project. Much of the reduction is achievable at the populous and water-stressed North China Plain and Northeast China. Meanwhile, the interventions can increase maize production by an estimated 7–15 %, meeting 22–28 % of demand increase projected for 2050. The water management and food production improvements obtained are crucial for achieving multiple Sustainable Development Goals (SDGs) related to water, land, and food in China and far beyond. © 2019 The Authors
- ItemCarbon lock-in through capital stock inertia associated with weak near-term climate policies(Amsterdam [u.a.] : Elsevier Science, 2013) Bertram, Christoph; Johnson, Nils; Luderer, Gunnar; Riahi, Keywan; Isaac, Morna; Eom, JiyongStringent long-term climate targets necessitate a limit on cumulative emissions in this century for which sufficient policy signals are lacking. Using nine energy-economy models, we explore how policies pursued during the next two decades impact long-term transformation pathways towards stringent long-term climate targets. Less stringent near-term policies (i.e., those with larger emissions) consume more of the long-term cumulative emissions budget in the 2010–2030 period, which increases the likelihood of overshooting the budget and the urgency of reducing GHG emissions after 2030. Furthermore, the larger near-term GHG emissions associated with less stringent policies are generated primarily by additional coal-based electricity generation. Therefore, to be successful in meeting the long-term target despite near-term emissions reductions that are weaker than those implied by cost-optimal mitigation pathways, models must prematurely retire significant coal capacity while rapidly ramping up low-carbon technologies between 2030 and 2050 and remove large quantities of CO2 from the atmosphere in the latter half of the century. While increased energy efficiency lowers mitigation costs considerably, even with weak near-term policies, it does not substantially reduce the short-term reliance on coal electricity. However, increased energy efficiency does allow the energy system more flexibility in mitigating emissions and, thus, facilitates the post-2030 transition.
- ItemVertical processes and resolution impact ice shelf basal melting: A multi-model study(Amsterdam [u.a.] : Elsevier Science, 2020) Gwyther, David E.; Kusahara, Kazuya; Asay-Davis, Xylar S.; Dinniman, Michael S.; Galton-Fenzi, Benjamin K.Understanding ice shelf–ocean interaction is fundamental to projecting the Antarctic ice sheet response to a warming climate. Numerical ice shelf–ocean models are a powerful tool for simulating this interaction, yet are limited by inherent model weaknesses and scarce observations, leading to parameterisations that are unverified and unvalidated below ice shelves. We explore how different models simulate ice shelf–ocean interaction using the 2nd Ice Shelf–Ocean Model Intercomparison Project (ISOMIP+) framework. Vertical discretisation and resolution of the ocean model are shown to have a significant effect on ice shelf basal melt rate, through differences in the distribution of meltwater fluxes and the calculation of thermal driving. Z-coordinate models, which generally have coarser vertical resolution in ice shelf cavities, may simulate higher melt rates compared to terrain-following coordinate models. This is due to the typically higher resolution of the ice–ocean boundary layer region in terrain following models, which allows better representation of a thin meltwater layer, increased stratification, and as a result, better insulation of the ice from water below. We show that a terrain-following model, a z-level coordinate model and a hybrid approach give similar results when the effective vertical resolution adjacent to the ice shelf base is similar, despite each model employing different paradigms for distributing meltwater fluxes and sampling tracers for melting. We provide a benchmark for thermodynamic ice shelf–ocean interaction with different model vertical coordinates and vertical resolutions, and suggest a framework for any future ice shelf–ocean thermodynamic parameterisations. © 2020 The Authors
- ItemLocked into Copenhagen pledges - Implications of short-term emission targets for the cost and feasibility of long-term climate goals(Amsterdam [u.a.] : Elsevier Science, 2013) Riahi, Keywan; Kriegler, Elmar; Johnson, Nils; Bertram, Christoph; den Elzen, Michel; Eom, Jiyong; Schaeffer, Michiel; Edmonds, Jae; Isaac, Morna; Krey, Volker; Longden, Thomas; Luderer, Gunnar; Méjean, Aurélie; McCollum, David L.; Mima, Silvana; Turton, Hal; van Vuuren, Detlef P.; Wada, Kenichi; Bosetti, Valentina; Capros, Pantelis; Criqui, Patrick; Hamdi-Cherif, Meriem; Kainuma, Mikiko; Edenhofer, OttmarThis paper provides an overview of the AMPERE modeling comparison project with focus on the implications of near-term policies for the costs and attainability of long-term climate objectives. Nine modeling teams participated in the project to explore the consequences of global emissions following the proposed policy stringency of the national pledges from the Copenhagen Accord and Cancún Agreements to 2030. Specific features compared to earlier assessments are the explicit consideration of near-term 2030 emission targets as well as the systematic sensitivity analysis for the availability and potential of mitigation technologies. Our estimates show that a 2030 mitigation effort comparable to the pledges would result in a further “lock-in” of the energy system into fossil fuels and thus impede the required energy transformation to reach low greenhouse-gas stabilization levels (450 ppm CO2e). Major implications include significant increases in mitigation costs, increased risk that low stabilization targets become unattainable, and reduced chances of staying below the proposed temperature change target of 2 °C in case of overshoot. With respect to technologies, we find that following the pledge pathways to 2030 would narrow policy choices, and increases the risks that some currently optional technologies, such as carbon capture and storage (CCS) or the large-scale deployment of bioenergy, will become “a must” by 2030.
- ItemCO2 emission mitigation and fossil fuel markets: Dynamic and international aspects of climate policies(Amsterdam [u.a.] : Elsevier Science, 2013) Bauer, Nico; Bosetti, Valentina; Hamdi-Cherif, Meriem; Kitous, Alban; McCollum, David; Méjean, Aurélie; Rao, Shilpa; Turton, Hal; Paroussos, Leonidas; Ashina, Shuichi; Calvin, Katherine; Wada, Kenichi; van Vuuren, DetlefThis paper explores a multi-model scenario ensemble to assess the impacts of idealized and non-idealized climate change stabilization policies on fossil fuel markets. Under idealized conditions climate policies significantly reduce coal use in the short- and long-term. Reductions in oil and gas use are much smaller, particularly until 2030, but revenues decrease much more because oil and gas prices are higher than coal prices. A first deviation from optimal transition pathways is delayed action that relaxes global emission targets until 2030 in accordance with the Copenhagen pledges. Fossil fuel markets revert back to the no-policy case: though coal use increases strongest, revenue gains are higher for oil and gas. To balance the carbon budget over the 21st century, the long-term reallocation of fossil fuels is significantly larger—twice and more—than the short-term distortion. This amplifying effect results from coal lock-in and inter-fuel substitution effects to balance the full-century carbon budget. The second deviation from the optimal transition pathway relaxes the global participation assumption. The result here is less clear-cut across models, as we find carbon leakage effects ranging from positive to negative because trade and substitution patterns of coal, oil, and gas differ across models. In summary, distortions of fossil fuel markets resulting from relaxed short-term global emission targets are more important and less uncertain than the issue of carbon leakage from early mover action.
- 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.
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