Early action on Paris Agreement allows for more time to change energy systems

The IMAGE integrated assessment model was used to develop a set of scenarios to evaluate the Nationally Determined Contributions (NDCs) submitted by Parties under the Paris Agreement. The scenarios project emissions and energy system changes under (i) current policies, (ii) implementation of the NDCs, and (iii) various trajectories to a radiative forcing level of 2.8 W/m2 in 2100, which gives a probability of about two thirds to limit warming to below 2 °C. The scenarios show that a cost-optimal pathway from 2020 onwards towards 2.8 W/m2 leads to a global greenhouse gas emission level of 38 gigatonne CO2 equivalent (GtCO2eq) by 2030, equal to a reduction of 20% compared to the 2010 level. The NDCs are projected to lead to 2030 emission levels of 50 GtCO2eq, which is still an increase compared to the 2010 level. A scenario that achieves the 2.8 W/m2 forcing level in 2100 from the 2030 NDC level requires more rapid transitions after 2030 to meet the forcing target. It shows an annual reduction rate in greenhouse gas emissions of 4.7% between 2030 and 2050, rapidly phasing out unabated coal-fired power plant capacity, more rapid scale-up of low-carbon energy, and higher mitigation costs. A bridge scenario shows that enhancing the ambition level of NDCs before 2030 allows for a smoother energy system transition, with average annual emission reduction rates of 4.5% between 2030 and 2050, and more time to phase out coal capacity.

[1]  Detlef P. van Vuuren,et al.  Future bio-energy potential under various natural constraints , 2009 .

[2]  B. D. Vries,et al.  The potential role of hydrogen in energy systems with and without climate policy , 2007 .

[3]  J. Rogelj,et al.  Paris Agreement climate proposals need a boost to keep warming well below 2 °C , 2016, Nature.

[4]  Keywan Riahi,et al.  WHAT DOES THE 2 C TARGET IMPLY FOR A GLOBAL CLIMATE AGREEMENT IN 2020? THE LIMITS STUDY ON DURBAN PLATFORM SCENARIOS , 2013 .

[5]  K. Keramidas,et al.  A global stocktake of the Paris pledges: Implications for energy systems and economy , 2016 .

[6]  E. Schmid,et al.  Climate change mitigation through livestock system transitions , 2014, Proceedings of the National Academy of Sciences.

[7]  Julia Larkin,et al.  Are major economies on track to achieve their pledges for 2020? An assessment of domestic climate and energy policies , 2014 .

[8]  Michael Obersteiner,et al.  Global cost estimates of reducing carbon emissions through avoided deforestation , 2008, Proceedings of the National Academy of Sciences.

[9]  J. Minx,et al.  Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change , 2014 .

[10]  K. Calvin,et al.  A MULTI-MODEL ANALYSIS OF POST-2020 MITIGATION EFFORTS OF FIVE MAJOR ECONOMIES , 2013 .

[11]  Kenichi Wada,et al.  Technological Forecasting & Social Change Locked into Copenhagen pledges — Implications of short-term emission targets for the cost and feasibility of long-term climate goals , 2014 .

[12]  D. Vuuren,et al.  The Emissions Gap Report 2012 , 2012 .

[13]  James R. McFarland,et al.  Can Paris pledges avert severe climate change? , 2015, Science.

[14]  Brian C. O'Neill,et al.  2020 emissions levels required to limit warming to below 2 °C , 2013 .

[15]  G. Giacomo,et al.  Quantifying the contribution of the Land Use sector to the Paris Climate Agreement , 2015 .

[16]  L. Clarke,et al.  Assessing Transformation Pathways , 2014 .

[17]  M. Obersteiner,et al.  Global forestry emission projections and abatement costs , 2012 .

[18]  K. Calvin,et al.  Post-2020 climate agreements in the major economies assessed in the light of global models , 2015 .

[19]  Michel G.J. den Elzen,et al.  Long-term reduction potential of non-CO2 greenhouse gases , 2007 .

[20]  Jan Christoph Steckel,et al.  Time to act now? Assessing the costs of delaying climate measures and benefits of early action , 2012, Climatic Change.

[21]  Malte Meinshausen,et al.  Copenhagen Accord Pledges imply higher costs for staying below 2°C warming , 2012, Climatic Change.

[22]  K. Calvin,et al.  Implications of weak near-term climate policies on long-term mitigation pathways , 2015, Climatic Change.

[23]  A. Hof,et al.  The effect of updated pledges and business-as-usual projections, and new agreed rules on expected global greenhouse gas emissions in 2020 , 2013 .

[24]  D. Vuuren,et al.  Integrated Assessment of Global Environmental Change with IMAGE 3.0 : Model description and policy applications , 2014 .

[25]  Bas Eickhout,et al.  Responses to technology and taxes in a simulated world , 2004 .

[26]  Elmar Kriegler,et al.  Economic mitigation challenges: how further delay closes the door for achieving climate targets , 2013 .

[27]  Detlef P. van Vuuren,et al.  Representation of variable renewable energy sources in TIMER, an aggregated energy system simulation model , 2017 .

[28]  John P. Weyant,et al.  The role of technology for achieving climate policy objectives: overview of the EMF 27 study on global technology and climate policy strategies , 2014, Climatic Change.

[29]  D. Vuuren,et al.  Assessing Pathways toward Ambitious Climate Targets at the Global and European levels: A Synthesis of Results from the AMPERE Project , 2014 .

[30]  R. Gerlagh,et al.  Optimal Timing of Climate Change Policy: Interaction Between Carbon Taxes and Innovation Externalities , 2009 .

[31]  N. Forsell,et al.  Contribution of the G20 economies to the global impact of the Paris agreement climate proposals , 2016, Climatic Change.

[32]  D. McCollum,et al.  Probabilistic cost estimates for climate change mitigation , 2013, Nature.

[33]  C. Müller,et al.  Energy, land-use and greenhouse gas emissions trajectories under a green growth paradigm , 2017 .

[34]  Detlef P. van Vuuren,et al.  Impact of the choice of emission metric on greenhouse gas abatement and costs , 2015 .