Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

A multi-model analysis of long-term emissions and warming implications of current mitigation efforts

This article has been updated


Most of the integrated assessment modelling literature focuses on cost-effective pathways towards given temperature goals. Conversely, using seven diverse integrated assessment models, we project global energy CO2 emissions trajectories on the basis of near-term mitigation efforts and two assumptions on how these efforts continue post-2030. Despite finding a wide range of emissions by 2050, nearly all the scenarios have median warming of less than 3 °C in 2100. However, the most optimistic scenario is still insufficient to limit global warming to 2 °C. We furthermore highlight key modelling choices inherent to projecting where emissions are headed. First, emissions are more sensitive to the choice of integrated assessment model than to the assumed mitigation effort, highlighting the importance of heterogeneous model intercomparisons. Differences across models reflect diversity in baseline assumptions and impacts of near-term mitigation efforts. Second, the common practice of using economy-wide carbon prices to represent policy exaggerates carbon capture and storage use compared with explicitly modelling policies.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Global energy CO2 emissions and temperature estimates.
Fig. 2: Decomposition of global energy CO2 emissions.
Fig. 3: Final energy consumption by fuel and by sector.
Fig. 4: CCS in carbon-price-only scenarios and in main scenarios.

Data availability

The datasets40 generated during, and analysed in, the current study are available from a public repository ( Source data are provided with this paper.

Code availability

The code for the analysis in this paper is available upon request to the corresponding author. The code availability for the individual models used in this paper varies and contact should be made to individual modelling groups. The GCAM model is available for download from Detailed model documentation for all seven models is available online at

Change history

  • 08 December 2021

    There were errors in the Fig. 1 Source Data initially presented online. The errors do not affect any conclusions in the paper, and the Source Data have been replaced as of 8 December 2021.


  1. The Paris Agreement (UNFCCC, 2020);

  2. Le Quéré, C. et al. Drivers of declining CO2 emissions in 18 developed economies. Nat. Clim. Change 9, 213–218 (2019).

    Article  Google Scholar 

  3. Roelfsema, M. et al. Taking stock of national climate policies to evaluate implementation of the Paris Agreement. Nat. Commun. 11, 2096 (2020).

    CAS  Article  Google Scholar 

  4. Hausfather, Z. & Peters, G. P. Emissions—the ‘business as usual’ story is misleading. Nature 577, 618–620 (2020).

    CAS  Article  Google Scholar 

  5. Grant, N., Hawkes, A., Napp, T. & Gambhir, A. The appropriate use of reference scenarios in mitigation analysis. Nat. Clim. Change 10, 605–610 (2020).

    Article  Google Scholar 

  6. IPCC Special Report on Global Warming of 1.5°C (eds Masson-Delmotte, V. et al.) (WMO, 2018).

  7. IPCC Climate Change 2014: Mitigation of Climate Change (eds Edenhofer, O. et al.) (Cambridge Univ. Press, 2014).

  8. Robinson, J. B. Futures under glass: a recipe for people who hate to predict. Futures 22, 820–842 (1990).

  9. Kriegler, E. et al. Making or breaking climate targets: the AMPERE study on staged accession scenarios for climate policy. Technol. Forecast. Soc. Change 90, 322–326 (2015).

    Google Scholar 

  10. Eskander, S. M. S. U. & Fankhauser, S. Reduction in greenhouse gas emissions from national climate legislation. Nat. Clim. Change 10, 750–756 (2020).

    CAS  Article  Google Scholar 

  11. Meckling, J. & Jenner, S. Varieties of market-based policy: instrument choice in climate policy. Environ. Polit. 25, 853–874 (2016).

    Article  Google Scholar 

  12. Bataille, C., Guivarch, C., Hallegatte, S., Rogelj, J. & Waisman, H. Carbon prices across countries. Nat. Clim. Change 8, 648–650 (2018).

    Article  Google Scholar 

  13. Jacoby, H. D., Chen, Y.-H. H. & Flannery, B. P. Informing transparency in the Paris Agreement: the role of economic models. Clim. Policy 17, 873–890 (2017).

    Article  Google Scholar 

  14. Aldy, J. et al. Economic tools to promote transparency and comparability in the Paris Agreement. Nat. Clim. Change 6, 1000–1004 (2016).

    Article  Google Scholar 

  15. Rogelj, J. et al. Understanding the origin of Paris Agreement emission uncertainties. Nat. Commun. 8, 15748 (2017).

    CAS  Article  Google Scholar 

  16. Rogelj, J. et al. Paris Agreement climate proposals need a boost to keep warming well below 2 °C. Nature 534, 631–639 (2016).

    CAS  Article  Google Scholar 

  17. Geiges, A. et al. Incremental improvements of 2030 targets insufficient to achieve the Paris Agreement goals. Earth Syst. Dyn. 11, 697–708 (2020).

    Article  Google Scholar 

  18. Fawcett, A. A. et al. Can Paris pledges avert severe climate change? Science 350, 1168–1169 (2015).

    CAS  Article  Google Scholar 

  19. Fujimori, S. et al. Implication of Paris Agreement in the context of long-term climate mitigation goals. Springerplus 5, 1620 (2016).

    Article  Google Scholar 

  20. Vandyck, T., Keramidas, K., Saveyn, B., Kitous, A. & Vrontisi, Z. A global stocktake of the Paris pledges: implications for energy systems and economy. Glob. Environ. Change 41, 46–63 (2016).

    Article  Google Scholar 

  21. Vrontisi, Z. et al. Enhancing global climate policy ambition towards a 1.5 °C stabilization: a short-term multi-model assessment. Environ. Res. Lett. 13, 044039 (2018).

    Article  Google Scholar 

  22. McCollum, D. L. et al. Energy investment needs for fulfilling the Paris Agreement and achieving the Sustainable Development Goals. Nat. Energy 3, 589–599 (2018).

    Article  Google Scholar 

  23. Jeffery, M. L., Gütschow, J., Rocha, M. R. & Gieseke, R. Measuring success: improving assessments of aggregate greenhouse gas emissions reduction goals. Earths Future 6, 1260–1274 (2018).

    Article  Google Scholar 

  24. Emissions Gap Report 2020 (UNEP, 2020).

  25. Giarola, S. et al. Challenges in the harmonisation of global integrated assessment models: a comprehensive methodology to reduce model response heterogeneity. Sci. Total Environ. 783, 146861 (2021).

    CAS  Article  Google Scholar 

  26. Krey, V. et al. Looking under the hood: a comparison of techno-economic assumptions across national and global integrated assessment models. Energy 172, 1254–1267 (2019).

    Article  Google Scholar 

  27. Jaxa-Rozen, M. & Trutnevyte, E. Sources of uncertainty in long-term global scenarios of solar photovoltaic technology. Nat. Clim. Change 11, 266–273 (2021).

    Article  Google Scholar 

  28. den Elzen, M. et al. Are the G20 economies making enough progress to meet their NDC targets? Energy Policy 126, 238–250 (2019).

    Article  Google Scholar 

  29. Dubash, N. K., Khosla, R., Rao, N. D. & Bhardwaj, A. India’s energy and emissions future: an interpretive analysis of model scenarios. Environ. Res. Lett. 13, 074018 (2018).

    Article  Google Scholar 

  30. Schaeffer, R. et al. Comparing transformation pathways across major economies. Climatic Change 162, 1787–1803 (2020).

    Article  Google Scholar 

  31. Harmsen, M. et al. Integrated assessment model diagnostics: key indicators and model evolution. Environ. Res. Lett. 16, 054046 (2021).

    Article  Google Scholar 

  32. Kriegler, E. et al. Diagnostic indicators for integrated assessment models of climate policy. Technol. Forecast. Soc. Change 90, 45–61 (2015).

    Article  Google Scholar 

  33. Keppo, I. et al. Exploring the possibility space: taking stock of the diverse capabilities and gaps in integrated assessment models. Environ. Res. Lett. 16, 053006 (2021).

    Article  Google Scholar 

  34. Hoesly, R. M. et al. Historical (1750–2014) anthropogenic emissions of reactive gases and aerosols from the Community Emissions Data System (CEDS). Geosci. Model Dev. 11, 369–408 (2018).

    CAS  Article  Google Scholar 

  35. Nikas, A. et al. Perspective of comprehensive and comprehensible multi-model energy and climate science in Europe. Energy 215, 119153 (2021).

    CAS  Article  Google Scholar 

  36. Meinshausen, M. et al. Emulating coupled atmosphere-ocean and carbon cycle models with a simpler model, MAGICC6 – Part 1: Model description and calibration. Atmos. Chem. Phys. 11, 1417–1456 (2011).

    CAS  Article  Google Scholar 

  37. Matthews, H. D. et al. Opportunities and challenges in using remaining carbon budgets to guide climate policy. Nat. Geosci. 13, 769–779 (2020).

    CAS  Article  Google Scholar 

  38. Peters, G. P. The ‘best available science’ to inform 1.5 °C policy choices. Nat. Clim. Change 6, 646–649 (2016).

    Article  Google Scholar 

  39. Riahi, K. et al. The Shared Socioeconomic Pathways and their energy, land use, and greenhouse gas emissions implications: an overview. Glob. Environ. Change 42, 153–168 (2017).

    Article  Google Scholar 

  40. Sognnaes, I. et al. Sognnaes_et_al_2021_NCC_DATASET version 1.1. Zenodo (2021).

Download references


I.S., A.A.-K., H.B., L.C., E.D., H.D., A.G., S.G., A.H., A.C.K., A.K., S.M., J.M., A.N., S.P., G.P.P., J.R., D.-J.v.d.V. and M.V. acknowledge support from the H2020 European Commission Project PARIS REINFORCE (grant no. 820846). N.G. was supported by the Natural Environment Research Council (NERC) (grant no. NE/L002515/1) as well as the Department for Business, Energy and Industrial Strategy (BEIS).

Author information

Authors and Affiliations



I.S. and G.P.P. coordinated the protocol for scenarios, which were designed by all authors, with notable contributions from L.C., H.D., A.G., S.G., A.C.K., S.M., A.N., S.P., J.R., D.-J.v.d.V. and M.V.; A.G., S.G., S.M., A.N. and D.-J.v.d.V. coordinated the harmonization protocol; all authors were involved in the model analysis, with notable contributions from D.-J.v.d.V., J.M. (GCAM), A.G., A.C.K., N.G., S.M. (TIAM), S.G., A.H. (MUSE), A.K. (FortyTwo), S.P., M.V. (GEMINI), L.C., E.D. (ICES), A.A.-K. and H.B. (E3ME). I.S. and G.P.P. compiled and analysed the results and created the figures, with feedback from all other authors. I.S. coordinated the conception and writing of the paper; all authors provided feedback and contributed to writing the paper.

Corresponding author

Correspondence to Ida Sognnaes.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information Nature Climate Change thanks Jennifer Morris and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data

Extended Data Fig. 1 Carbon price scenario implementation.

a, Implementation of CP_Price scenarios. First, current policies are explicitly implemented to 2030, and the resulting emissions in 2030 are recorded. Second, models are re-run to reach the same levels of emissions as in the previous step using a carbon price (C1) alone. Third, scenarios are extended post-2030 by growing the carbon price (C1) with GDP per capita. The resulting emissions pathways (P1(t)) are recorded. Fourth, models are re-run with current policies explicitly implemented to 2030, and as constant or minimum bounds on effort post-2030. The emissions pathways achieved in the previous step (P1(t)) are implemented as upper bounds on emissions. b, Implementation of NDC_Price scenarios follows the implementation of CP_Price scenarios, except for the first step. First, current policies are explicitly implemented to 2030. Then, the emissions levels achieved in 2030 in each model region are compared with NDC targets. When additional effort is required to achieve NDC targets, this is implemented on top of current policies. See Supplementary Text 2 for the full scenario protocol.

Supplementary information

Supplementary Information

Supplementary Figs. 1–11, Tables 1–4, Text 1–5 and references.

Supplementary Data

Inventory of current policies used in the analysis.

Source data

Source Data Fig. 1

Data for Fig. 1.

Source Data Fig. 2

Data for Fig. 2.

Source Data Fig. 3

Data for Fig. 3.

Source Data Fig. 4

Data for Fig. 4.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Sognnaes, I., Gambhir, A., van de Ven, DJ. et al. A multi-model analysis of long-term emissions and warming implications of current mitigation efforts. Nat. Clim. Chang. 11, 1055–1062 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing