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Economic tools to promote transparency and comparability in the Paris Agreement


The Paris Agreement culminates a six-year transition towards an international climate policy architecture based on parties submitting national pledges every five years1. An important policy task will be to assess and compare these contributions2,3. We use four integrated assessment models to produce metrics of Paris Agreement pledges, and show differentiated effort across countries: wealthier countries pledge to undertake greater emission reductions with higher costs. The pledges fall in the lower end of the distributions of the social cost of carbon and the cost-minimizing path to limiting warming to 2 °C, suggesting insufficient global ambition in light of leaders’ climate goals. Countries’ marginal abatement costs vary by two orders of magnitude, illustrating that large efficiency gains are available through joint mitigation efforts and/or carbon price coordination. Marginal costs rise almost proportionally with income, but full policy costs reveal more complex regional patterns due to terms of trade effects.

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Figure 1: Average 2025–2030 mitigation costs and emission reductions for the four models and seven major economies.
Figure 2: Average 2025–2030 marginal abatement costs for the four models.
Figure 3: Average 2025–2030 mitigation costs (marginal abatement costs on the vertical axis, and % GDP losses proportional to markers size) in relation to average 2025–2030 per capita income for the four models, and seven major economies.


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The Research Institute of Innovative Technology for the Earth provided financial support for this project. L.E.C., J.E., G.C.I. and H.C.M. were supported by the Global Technology Strategy Project. The views expressed here reflect those of the individual authors and not necessarily those of EPRI or its members.

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J.A., K.A., W.P. and M.T. were responsible for project planning and scenario design. K.A., L.A.R., G.B., C.C., L.E.C., J.E., G.C.I., H.C.M., R.R., S.R., F.S. and M.T. contributed to the modelling results. J.A., L.A.R., W.P. and M.T. undertook the synthesis of the analyses. J.A., W.P. and M.T. drafted the paper.

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Correspondence to Joseph Aldy.

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Aldy, J., Pizer, W., Tavoni, M. et al. Economic tools to promote transparency and comparability in the Paris Agreement. Nature Clim Change 6, 1000–1004 (2016).

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