2020, Roelfsema, Mark, van Soest, Heleen L., Harmsen, Mathijs, van Vuuren, Detlef P., Bertram, Christoph, den Elzen, Michel, Höhne, Niklas, Iacobuta, Gabriela, Krey, Volker, Kriegler, Elmar, Luderer, Gunnar, Riahi, Keywan, Ueckerdt, Falko, Després, Jacques, Drouet, Laurent, Emmerling, Johannes, Frank, Stefan, Fricko, Oliver, Gidden, Matthew, Humpenöder, Florian, Huppmann, Daniel, Fujimori, Shinichiro, Fragkiadakis, Kostas, Gi, Keii, Keramidas, Kimon, Köberle, Alexandre C., Aleluia Reis, Lara, Rochedo, Pedro, Schaeffer, Roberto, Oshiro, Ken, Vrontisi, Zoi, Chen, Wenying, Iyer, Gokul C., Edmonds, Jae, Kannavou, Maria, Jiang, Kejun, Mathur, Ritu, Safonov, George, Vishwanathan, Saritha Sudharmma

Many countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario analysis, we show that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO2eq by 2030 with the optimal pathways to implement the well below 2 °C and 1.5 °C Paris goals. If Nationally Determined Contributions would be fully implemented, this gap would be reduced by a third. Interestingly, the countries evaluated were found to not achieve their pledged contributions with implemented policies (implementation gap), or to have an ambition gap with optimal pathways towards well below 2 °C. This shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossil-fuel-dependent countries.

2019, Oshiro, Ken, Gi, Keii, Fujimori, Shinichiro, van Soest, Heleen L., Bertram, Christoph, Després, Jacques, Masui, Toshihiko, Rochedo, Pedro, Roelfsema, Mark, Vrontisi, Zoi

This study assesses Japan’s mid-century low-emission pathways using both national and global integrated assessment models in the common mitigation scenario framework, based on the carbon budgets corresponding to the global 2 °C goal. We examine high and low budgets, equal to global cumulative 1600 and 1000 Gt-CO2 (2011–2100) for global models, and 36 and 31 Gt-CO2 (2011–2050) in Japan for national models, based on the cost-effectiveness allocation performed by the global models. The impacts of near-term policy assumption, including the implementation and enhancement of the 2030 target of the nationally determined contribution (NDC), are also considered. Our estimates show that the low budget scenarios require a 75% reduction of CO2 emissions by 2050 below the 2010 level, which is nearly the same as Japan’s governmental 2050 goal of reducing greenhouse gas emissions by 80%. With regard to near-term actions, Japan’s 2030 target included in the NDC is on track to meet the high budget scenario, whereas it is falling short for the low budget scenario, which would require emission reductions immediately after 2020. Whereas models differ in the type of energy source on which they foresee Japan basing its decarbonization process (e.g., nuclear- or variable renewable energy-dependent), the large-scale deployment of low-carbon energy (nuclear, renewable, and carbon capture and storage) is shared across most models in both the high and low budget scenarios. By 2050, low-carbon energy represents 44–54% of primary energy and 86–97% of electricity supply in the high and low budget scenarios, respectively. © 2019, The Author(s).

2020, Malik, Aman, Bertram, Christoph, Despres, Jacques, Emmerling, Johannes, Fujimori, Shinichiro, Garg, Amit, Kriegler, Elmar, Luderer, Gunnar, Mathur, Ritu, Roelfsema, Mark, Shekhar, Swapnil, Vishwanathan, Saritha, Vrontisi, Zoi

Cost-effective achievement of the Paris Agreement's long-term goals requires the unanimous phase-out of coal power generation by mid-century. However, continued investments in coal power plants will make this transition difficult. India is one of the major countries with significant under construction and planned increase in coal power capacity. To ascertain the likelihood and consequences of the continued expansion of coal power for India's future mitigation options, we use harmonised scenario results from national and global models along with projections from various government reports. Both these approaches estimate that coal capacity is expected to increase until 2030, along with rapid developments in wind and solar power. However, coal capacity stranding of the order of 133–237 GW needs to occur after 2030 if India were to pursue an ambitious climate policy in line with a well-below 2 °C target. Earlier policy strengthening starting after 2020 can reduce stranded assets (14–159 GW) but brings with it political economy and renewable expansion challenges. We conclude that a policy limiting coal plants to those under construction combined with higher solar targets could be politically feasible, prevent significant stranded capacity, and allow higher mitigation ambition in the future.