2013, Bertram, Christoph, Johnson, Nils, Luderer, Gunnar, Riahi, Keywan, Isaac, Morna, Eom, Jiyong

Stringent 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.

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, Ottmar

This 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.

2018, Krey, Volker, Guo, Fei, Kolp, Peter, Zhou, Wenji, Schaeffer, Roberto, Awasthy, Aayushi, Bertram, Christoph, de Boer, Harmen-Sytze, Fragkos, Panagiotis, Fujimori, Shinichiro, He, Chenmin, Iyer, Gokul, Keramidas, Kimon, Köberle, Alexandre C., Oshiro, Ken, Reis, Lara Aleluia, Shoai-Tehrani, Bianka, Vishwanathan, Saritha, Capros, Pantelis, Drouet, Laurent, Edmonds, James E., Garg, Amit, Gernaat, David E.H.J., Jiang, Kejun, Kannavou, Maria, Kitous, Alban, Kriegler, Elmar, Luderer, Gunnar, Mathur, Ritu, Muratori, Matteo, Sano, Fuminori, van Vuuren, Detlef P.

Integrated assessment models are extensively used in the analysis of climate change mitigation and are informing national decision makers as well as contribute to international scientific assessments. This paper conducts a comprehensive review of techno-economic assumptions in the electricity sector among fifteen different global and national integrated assessment models. Particular focus is given to six major economies in the world: Brazil, China, the EU, India, Japan and the US. The comparison reveals that techno-economic characteristics are quite different across integrated assessment models, both for the base year and future years. It is, however, important to recognize that techno-economic assessments from the literature exhibit an equally large range of parameters as the integrated assessment models reviewed. Beyond numerical differences, the representation of technologies also differs among models, which needs to be taken into account when comparing numerical parameters. While desirable, it seems difficult to fully harmonize techno-economic parameters across a broader range of models due to structural differences in the representation of technology. Therefore, making techno-economic parameters available in the future, together with of the technology representation as well as the exact definitions of the parameters should become the standard approach as it allows an open discussion of appropriate assumptions. © 2019 The Authors