Solely economic mitigation strategy suggests upward revision of nationally determined contributions

•We review the 2030 NDCs from an economic perspective•We provide a solely mitigation pathway up to 2100 for 15 regions•The India and Russia are higher secure economically favorable level•Countries can further reduce emissions achieve efficiency globally The Paris Agreement relies on reviewing process of national climate commitments produce enhanced pledges by virtue comparisons. At present, most reviews based equity principles, which countries have little agreement on. This paper provides alternative perspective current discussion treats emission reduction as behavior motivated avoiding future damages change. Assuming no consensus over or international cooperation, we generate 2100. each term, damage caused additional unit carbon is than cost. path be informative control their at level while providing comparing pledges. use principles nationally determined contributions (NDCs) critical facilitating more ambitious actions. However, disagreement persists. We instead treat until Using value in NDCs, find that China, USA, EU 1.5, 1.4, 0.9 respective GtCO2eq lower levels, whereas commits 3.8 its level. also propose equal-effort cooperation scenario toward 2°C where country reduces 28% levels 2030. Through exploration trade-offs, our results suggest urgently needed. regime entered new stage after was adopted 2015, set (NDCs, all abbreviations found Table 1) context priorities. With legally binding constraints near key driver accomplishing these goals “pledge review” system, put forward commitment assess progress periodically.2Jacquet J. Jamieson D. Soft but significant power Agreement.Nat. Clim. Chang. 2016; 6: 643-646https://doi.org/10.1038/nclimate3006Crossref Scopus (43) Google Scholar Taking stock collective producing comparisons.3UNFCCC (Adoption Agreement. Report no. FCCC/CP/2015/L.9/Rev.1.2015http://unfccc.int/resource/docs/2015/cop21/eng/l09r01.pdfGoogle Scholar,4Rogelj Den Elzen M. Höhne N. Fransen T. Fekete H. Winkler Schaeffer R. Sha F. Riahi K. Meinshausen proposals need boost keep warming well below 2°C.Nature. 534: 631-639https://doi.org/10.1038/nature18307Crossref PubMed (1428) has been made operationalization following common differentiated responsibilities capability (CBDR-RC) principles. Therefore, aspects conducting NDC review, ranks compares efforts, using conducted allocating 1.5°C global budgets with criteria.5Intergovernmental Panel Climate ChangeClimate Change 2014: Mitigation Change. Cambridge University Press, 2015Google Scholar, 6Höhne Escalante Regional GHG targets effort sharing: comparison studies.Clim. Policy. 2014; 14: 122-147https://doi.org/10.1080/14693062.2014.849452Crossref (123) 7Robiou du Pont Y. Jeffery M.L. Gütschow Rogelj Christoff P. Equitable goals.Nat. 2017; 7: 38-43https://doi.org/10.1038/nclimate3186Crossref (127) Ambitious those commit allocation results. Equity quantified into five categories: responsibility,8Wei Y.M. Wang L. Liao Murty Yan Responsibility accounting allocation: perspective.Appl. Energ. 130: 122-133https://doi.org/10.1016/j.apenergy.2014.05.025Crossref (57) capability,9Den Sharing limit 2°C.Clim. 2010; 10: 247-260https://doi.org/10.3763/cpol.2009.0678ACrossref equality,10Chakravarty S. Chikkatur A. De Coninck Pacala Socolow Tavoni CO2 reductions among one billion high emitters.Proc. Natl. Acad. Sci. USA. 2009; 106: 11884-11888https://doi.org/10.1073/pnas.0905232106Crossref (227) responsibility-capability need,11Baer Fieldman G. Athanasiou Kartha Greenhouse development rights: towards equitable framework policy.Camb. Rev. Int. Aff. 2008; 21: 649-669https://doi.org/10.1080/09557570802453050Crossref (47) equal cumulative per capita emissions.12Raupach M.R. Raupach Davis S.J. Peters G.P. Andrew R.M. Canadell J.G. Ciais Friedlingstein Jotzo Van Vuuren D.P. et al.Sharing quota emissions.Nat. 4: 873-879https://doi.org/10.1038/nclimate2384Crossref (209) Scholar,13Pan X. Teng Ha access sustainable development: comparative study rights schemes.Appl. 632-640https://doi.org/10.1016/j.apenergy.2014.03.072Crossref (30) varies significantly when applying different approach agreed upon countries.14Schroeder Boykoff M.T. Spiers state representations negotiations.Nat. 2012; 2: 834-836https://doi.org/10.1038/nclimate1742Crossref (48) Scholar,15Keohane R.O. Victor D.G. Cooperation discord policy.Nat. 570-575https://doi.org/10.1038/nclimate2937Crossref (148) A suite studies combined effort-sharing proposed hybrid adopts least stringent principle realize goal.16Meinshausen Guetschow Du Y.R. Oberthür National post-2020 greenhouse gas diversity-aware leadership.Nat. 2015; 5: 1098-1106https://doi.org/10.1038/nclimate2826Crossref (63) Scholar,17Robiou Warming assessment bottom-up pledges.Nat. Commun. 2018; 9: 4810https://doi.org/10.1038/s41467-018-07223-9Crossref (45) do not consider mitigation. Comparatively, cost-effectiveness approach, usually realized via integrated models (IAMs), developed.18Aldy Pizer W. Reis L.A. Akimoto Blanford Carraro C. Clarke L.E. Edmonds Iyer G.C. al.Economic tools promote transparency comparability 1000-1004https://doi.org/10.1038/nclimate3106Crossref (77) 19Tavoni Kriegler E. Aboumahboub Calvin de Maere Wise Klein Jewell Kober Lucas al.The distribution major economies' Durban Platform scenarios.Clim. Econ. 2013; 1340009https://doi.org/10.1142/S2010007813400095Crossref (59) 20Wei Han Liang Q.M. Yu B.Y. Yao Y.F. Xue M.M. Zhang Liu L.J. Peng Yang al.An INDCs under Shared Socioeconomic Pathways: implementation C3IAM.Nat. Hazards. 92: 585-618https://doi.org/10.1007/s11069-018-3297-9Crossref (34) It calculated total cost minimization equalizing marginal abatement depending model structure.21Mi Z. Coffman D.M. Wei Assessment policy model.Nat. 2019; 95: 309-323https://doi.org/10.1007/s11069-018-3408-7Crossref (8) Robiou al. cost-effective equality allocated cost-optimal IAMs approach.7Robiou Scholar,22Robiou decarbonizing world economy line G7 Agreement.Environ. Res. Lett. 11: 054005Crossref (28) benefits associated decarbonization (i.e., avoided damage) were masked23Ringius Torvanger Underdal Burden sharing fairness policy.Int. Environ. Agreem-P. 2002; 1-22https://doi.org/10.1023/A:1015041613785Crossref Scholar,24Zenghelis mitigation.Nat. 9-10https://doi.org/10.1038/nclimate3192Crossref (4) thus could incentive optimum action reducing change.25Iyer Hultman Hartin McJeon Aldy Implications considerations across contributions.Nat. 8: 124-129https://doi.org/10.1038/s41558-017-0039-zCrossref recent introduced self-preservation strategy.26Wei B. Yuan X.C. Chang Zhao Q. Tang al.Self-preservation strategy approaching post-Paris era.Nat. 2020; 1624https://doi.org/10.1038/s41467-020-15453-zCrossref (31) offers net benefit within this century represented built assumption four used calculation. To facilitate extended strategies noncooperative perspective. Our approaches perspective, balances costs benefits. Countries invest damage. regarded reduction, monetized aggregation both market nonmarket loss related Market includes physical hazards (such droughts cyclones), losses hard reflect values, such impact mortality crime. equalize long term region Integrated Climate-Economy (RICE) model.27Nordhaus W.D. regional dynamic general-equilibrium climate-change strategies.Am. 1996; 86: 741-765http://www.jstor.org/stable/2118303Google Scholar,28Nordhaus Economic post-Copenhagen environment.Proc. 107: 11721-11726https://doi.org/10.1073/pnas.1005985107Crossref (297) In scenario, demerit output optimized regarding time. decisions will jointly affect temperature; therefore, Nash equilibrium decision-making theorem calculate Pareto optimality, means welfare gain changing strategies. resulting trajectory suggests ceiling equalized (the ton emission) point Exceeding lead costs. RICE widely employed investigate equilibria social carbon.29Nordhaus clubs: overcoming free-riding policy.Am. 105: 1339-1370https://doi.org/10.1257/aer.15000001Crossref (355) 30Kotchen M.J. Which carbon? theoretical perspective.J. Assoc. Resour. 673-694https://doi.org/10.1086/697241Crossref (12) 31Chen Zeckhauser Collective asymmetric world.J. Public 158: 103-112https://doi.org/10.1016/j.jpubeco.2017.12.009Crossref (6) version Dynamic [DICE] model) three array energy, air pollution, change regulations US.32California Assembly Bill 197 (AB-197) (2016).Google 33Schlatter Findings Fact, Conclusions, Recommendations: Carbon Dioxide Values State Minnesota. Office Administrative Hearings, 2016Google 34Larson Subsidies New York's upstate plants.https://www.powermag.com/subsidies-proposed-for-new-yorks-upstate-nuclear-power-plants/Date: 35Yang Mi Cao Y.,M. Social shared socioeconomic pathways.Glob. 53: 225-232https://doi.org/10.1016/j.gloenvcha.2018.10.001Crossref (19) rigorous transparent modeling framework, conduct two aspects. “Mitigation” indicates absolute amount defined gap between optimal commitment. “Effort” percentage compared cost-benefit emission. index standardizes makes comparable countries. reached Although theoretically optimal, they subject without any cooperation. International allows high-mitigation-cost transfer effort, general cost, having improvement all. challenged free-rider intentions, say others themselves contributing efforts would impose citizens.36Lattanzio R.K. Financing: Green Fund (GCF). Congressional Research Service, 2014https://www.everycrsreport.com/files/20140505_R41889_9d0d7f034c21dca729f78a95d52371abed94f678.pdfGoogle Scholar,37Green Annex IV: Status Fund.in: Seventh Conference Parties United Nations Framework Convention 2015: 80-83Google Because achieve, assume equity. rational thereby enhancing light vulnerability risk aversion calculation rather consistent year. If country’s emissions, it inefficient. facilitates through identification relative quantities. compare quantities reduction. Effort Index (NEI) denote change, quantity divided emissions. helps recognize small emitters. Balancing assumption, aspects, supplement regions according regime. formally stated emission-reduction Kyoto Protocol (also known Annex-B countries) grouped six. US, (including UK), Russia, Canada, Japan taken separately, rest other Four developing taking negotiations BASIC group), namely India, Brazil, South Africa, analyzed separately. ease computational difficulties, geographical locations, Middle East Africa (MAF; exception Africa), Asia (OAS; East, Japan, former Soviet Union states), Latin America Caribbean (LAM; Brazil), reforming economies Eastern Europe (REF), (OEU). above definitions MAF, OAS, LAM context. Detailed information provided supplemental experimental procedures. account uncertainty preferences (Figure 1, range gray) then allocations (capability, constant ratio, capita, right) al.7Robiou colored range). Capability emphasizes availability resources mitigate allocates gross domestic product (GDP). ratio “grandfathering law”) maintains base year’s rate. Equal strengthens historical responsibility populations low-carbon budgets. convergence period. right preserves “right development” weighted index. Further details competing methodologies Check (http://paris-equity-check.org/) S3. Under assumptions, temperature consideration gray range) generally increase beginning slow down result severe end century. (GHG) show declining trend peak. conservative estimations fossil-fueled (SSP5), many throughout According GDP projections (SSP) database, MAF OAS expected fast considering only benefits, increasing time average surface 3.5°C–4°C, much goal suggested; cases, allocation. inconsistency shown; example, constant-emission-ratio quotas developed emit today. contrast, equal-cumulative-per-capita allocate space because less some receive needs. Following allocations, concern liability abilities pay, possibility emitting Similar applied REF estimated damage, if highest suggested, pioneers laggards identified mostly similar, although there few exceptions. America, satisfied efficient. India's 0.8 GtCO2eq. committing 3 NDC. conforms rights, purely indicating facing sensitivity tests, including uncertainty, test discount rate, productivity, (see Tables S1 S2). dominant effect path. represents governments’ attitude considerable. Combating long-term involving multiple generations, rate presents generational preference decision making. valuing crucial determining given concerns maker future. Within Ramsey (STP) elasticity utility consumption (EMUC). STP describes time, reflecting consume earlier later, seen EMUC measures regardless timing. previous discussions Intergovernmental (IPCC) suggestions, discuss 0.5% 2.5% 0.5 2.5.5Intergovernmental Scholar,38Glanemann Willner S.N. Levermann passes test.Nat. 110https://doi.org/10.1038/s41467-019-13961-1Crossref (42) Apart parameters above, development, reflected SSPs variables. SSP driven harmonized projection population descriptive narrative diverse fields. too simplified sectoral characteristics, Global Analysis Model (GCAM) Assess Environment (IMAGE) characterize RICE. shown Figure 2. source remarkably diverse. denotes EMUC. nine sets illustrated 2, covers (0.5%, 1.5%, 2.5%) (0.5, 2.5). speed relatively median decline intensity, SSP5 widest greater prospect increase. Besides SSP5, rivalry (SSP3) depicts fragmentation low growth intensity limited institutions strong orientation security, rapidly OEU countries, REF. On basis analysis regard build NEI intuitive score ambition. committed define procedures). Higher pledge accordingly. calibration,39Nordhaus Revisiting carbon.Proc. 114: 1518-1523https://doi.org/10.1073/pnas.1609244114Crossref (341) choose 1.5% = 1.5 commonly government literature. slightly differ sensitive paths 3, pie chart). factors growth, population, relationship, technological diffusion adaptation challenges. aspect paths. black ring border chart SSPs. denoted assumptions. From SSP1 (sustainable development)