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How Should Benefits and Costs Be Discounted in an Intergenerational Context? The Views of an Expert Panel


  • Arrow, Kenneth J.
  • Cropper, Maureen L.

    () (Resources for the Future)

  • Gollier, Christian
  • Groom, Ben
  • Heal, Geoffrey M.
  • Newell, Richard G.
  • Nordhaus, William D.
  • Pindyck, Robert S.
  • Pizer, William A.
  • Portney, Paul R.
  • Sterner, Thomas
  • Tol, Richard S. J.
  • Weitzman, Martin L.


In September 2011, the US Environmental Protection Agency asked 12 economists how the benefits and costs of regulations should be discounted for projects that affect future generations. This paper summarizes the views of the panel on three topics -- the use of the Ramsey formula as an organizing principle for determining discount rates over long horizons, whether the discount rate should decline over time, and how intra- and intergenerational discounting practices can be made compatible. The panel members agree that the Ramsey formula provides a useful framework for thinking about intergenerational discounting. We also agree that theory provides compelling arguments for a declining certainty-equivalent discount rate. In the Ramsey formula, uncertainty about the future rate of growth in per capita consumption can lead to a declining consumption rate of discount, assuming that shocks to consumption are positively correlated. This uncertainty in future consumption growth rates may be estimated econometrically based on historic observations, or it can be derived from subjective uncertainty about the mean rate of growth in mean consumption or its volatility. Determining the remaining parameters of the Ramsey formula is, however, challenging.

Suggested Citation

  • Arrow, Kenneth J. & Cropper, Maureen L. & Gollier, Christian & Groom, Ben & Heal, Geoffrey M. & Newell, Richard G. & Nordhaus, William D. & Pindyck, Robert S. & Pizer, William A. & Portney, Paul R. & , 2012. "How Should Benefits and Costs Be Discounted in an Intergenerational Context? The Views of an Expert Panel," Discussion Papers dp-12-53, Resources For the Future.
  • Handle: RePEc:rff:dpaper:dp-12-53

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    References listed on IDEAS

    1. Christian Gollier & Phoebe Koundouri & Theologos Pantelidis, 2008. "Declining discount rates: Economic justifications and implications for long-run policy," Economic Policy, CEPR;CES;MSH, vol. 23, pages 757-795, October.
    2. Hepburn, Cameron & Koundouri, Phoebe & Panopoulou, Ekaterini & Pantelidis, Theologos, 2009. "Social discounting under uncertainty: A cross-country comparison," Journal of Environmental Economics and Management, Elsevier, vol. 57(2), pages 140-150, March.
    3. Christian Gollier, 2008. "Discounting with fat-tailed economic growth," Journal of Risk and Uncertainty, Springer, vol. 37(2), pages 171-186, December.
    4. Christian Gollier, 2012. "Pricing the Planet's Future: The Economics of Discounting in an Uncertain World," Economics Books, Princeton University Press, edition 1, number 9894.
    5. Cochrane, John H, 1988. "How Big Is the Random Walk in GNP?," Journal of Political Economy, University of Chicago Press, vol. 96(5), pages 893-920, October.
    6. Gollier, Christian, 2002. "Time Horizon and the Discount Rate," Journal of Economic Theory, Elsevier, vol. 107(2), pages 463-473, December.
    7. repec:wsi:ccexxx:v:03:y:2012:i:04:n:s2010007812500248 is not listed on IDEAS
    8. Robert J. Barro, 2009. "Rare Disasters, Asset Prices, and Welfare Costs," American Economic Review, American Economic Association, vol. 99(1), pages 243-264, March.
    9. Newell, Richard G. & Pizer, William A., 2003. "Discounting the distant future: how much do uncertain rates increase valuations?," Journal of Environmental Economics and Management, Elsevier, vol. 46(1), pages 52-71, July.
    10. Lawrence H. Goulder & Roberton C. Williams, 2012. "The Choice Of Discount Rate For Climate Change Policy Evaluation," Climate Change Economics (CCE), World Scientific Publishing Co. Pte. Ltd., vol. 3(04), pages 1-18.
    11. Robert J. Barro, 2006. "Rare Disasters and Asset Markets in the Twentieth Century," The Quarterly Journal of Economics, Oxford University Press, vol. 121(3), pages 823-866.
    12. Phoebe Koundouri & Theologos Pantelidis & Ben Groom & Ekaterini Panopoulou, 2007. "Discounting the distant future: How much does model selection affect the certainty equivalent rate?," Journal of Applied Econometrics, John Wiley & Sons, Ltd., vol. 22(3), pages 641-656.
    13. Weitzman, Martin L., 1998. "Why the Far-Distant Future Should Be Discounted at Its Lowest Possible Rate," Journal of Environmental Economics and Management, Elsevier, vol. 36(3), pages 201-208, November.
    14. Donald Meyer & Jack Meyer, 2005. "Relative Risk Aversion: What Do We Know?," Journal of Risk and Uncertainty, Springer, vol. 31(3), pages 243-262, December.
    15. Narayana R. Kocherlakota, 1996. "The Equity Premium: It's Still a Puzzle," Journal of Economic Literature, American Economic Association, vol. 34(1), pages 42-71, March.
    16. Mankiw, N. Gregory, 1981. "The permanent income hypothesis and the real interest rate," Economics Letters, Elsevier, vol. 7(4), pages 307-311.
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    Cited by:

    1. W. A. Brock & A. Xepapadeas, 2015. "Modeling Coupled Climate, Ecosystems, and Economic Systems," Working Papers 2015.66, Fondazione Eni Enrico Mattei.
    2. Freeman, Mark C. & Groom, Ben, 2016. "How certain are we about the certainty-equivalent long term social discount rate?," Journal of Environmental Economics and Management, Elsevier, vol. 79(C), pages 152-168.
    3. Rautiainen, Aapo & Lintunen, Jussi, 2017. "Social Cost of Forcing: A Basis for Pricing All Forcing Agents," Ecological Economics, Elsevier, vol. 133(C), pages 42-51.
    4. Lugovoy, O. & Polbin, A., 2016. "On Intergenerational Distribution of the Burden of Greenhouse Gas Emissions," Journal of the New Economic Association, New Economic Association, vol. 31(3), pages 12-39.
    5. repec:eee:forpol:v:83:y:2017:i:c:p:58-69 is not listed on IDEAS
    6. Fesselmeyer, Eric & Liu, Haoming & Salvo, Alberto, 2016. "How Do Households Discount over Centuries? Evidence from Singapore's Private Housing Market," IZA Discussion Papers 9862, Institute for the Study of Labor (IZA).
    7. Eli P. Fenichel & Matthew J. Kotchen & Ethan T. Addicott, 2017. "Even the Representative Agent Must Die: Using Demographics to Inform Long-Term Social Discount Rates," NBER Working Papers 23591, National Bureau of Economic Research, Inc.
    8. Moore Mark A. & Vining Aidan R. & Boardman Anthony E., 2013. "More appropriate discounting: the rate of social time preference and the value of the social discount rate," Journal of Benefit-Cost Analysis, De Gruyter, vol. 4(1), pages 1-16, March.
    9. Bernard Lapeyre & Emile Quinet, 2017. "A Simple GDP-based Model for Public Investments at Risk," Post-Print hal-01666574, HAL.

    More about this item


    discount rate; uncertainty; declining discount rate; benefit-cost analysis;

    JEL classification:

    • D61 - Microeconomics - - Welfare Economics - - - Allocative Efficiency; Cost-Benefit Analysis

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