Modified Ramsey Discounting for Climate Change

20 Pages Posted: 3 Dec 2015

See all articles by Richard S. J. Tol

Richard S. J. Tol

VU University Amsterdam - Institute for Environmental Studies (IVM); Carnegie Mellon University - Center for Integrated Study of the Human Dimensions of Global Change; University of Hamburg - Centre for Marine and Climate Research (ZMK); Princeton University

Date Written: November 9, 2015

Abstract

The Ramsey rule for the consumption rate of discount assumes a transfer of money of a (representative) agent at one point in time to the same agent at another point in time. Climate policy (implicitly) transfers money not just over time but also between agents. I propose three alternative modifications of the Ramsey rule to account for this. Taking the Ramsey rule as given, I derive an intuitively clear but ad hoc modification. Using the assumptions underlying the Ramsey rule, I derive a consistent but more elaborate modification. If the discount rate is differentiated by victim, the consistent modified Ramsey rule is simpler and identical to regional equity weights. I apply the modified Ramsey rules to estimates of the marginal damage costs of carbon dioxide emissions. The results confirm that optimal climate policy has differentiated carbon taxes. Results also show that the standard Ramsey rule drastically underestimates the social cost of carbon.

Keywords: climate change, social cost of carbon, discount rate, Ramsey rule, equity

JEL Classification: H430, D630, Q540

Suggested Citation

Tol, Richard S. J., Modified Ramsey Discounting for Climate Change (November 9, 2015). CESifo Working Paper Series No. 5588, Available at SSRN: https://ssrn.com/abstract=2698609

Richard S. J. Tol (Contact Author)

VU University Amsterdam - Institute for Environmental Studies (IVM) ( email )

De Boelelaan 1115
Amsterdam, 1081 HV
Netherlands
+31 20 444 9555 (Phone)
+31 20 444 9553 (Fax)

Carnegie Mellon University - Center for Integrated Study of the Human Dimensions of Global Change

Pittsburgh, PA 15213-3890
United States

University of Hamburg - Centre for Marine and Climate Research (ZMK)

Troplowitzstrasse 7
D-22529 Hamburg
Germany

Princeton University ( email )

22 Chambers Street
Princeton, NJ 08544-0708
United States

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