Intertemporal Equity and Hartwick's Rules in an Exhaustible Resource Model
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- Wolfgang Buchholz & Swapan Dasgupta & Tapan Mitra, 2005. "Intertemporal Equity and Hartwick's Rule in an Exhaustible Resource Model," Scandinavian Journal of Economics, Wiley Blackwell, vol. 107(3), pages 547-561, September.
References listed on IDEAS
- Avinash Dixit & Peter Hammond & Michael Hoel, 1980. "On Hartwick's Rule for Regular Maximin Paths of Capital Accumulation and Resource Depletion," The Review of Economic Studies, Review of Economic Studies Ltd, vol. 47(3), pages 551-556.
- Heal, Geoffrey M., 1993.
"The optimal use of exhaustible resources,"
Handbook of Natural Resource and Energy Economics, in: A. V. Kneese† & J. L. Sweeney (ed.), Handbook of Natural Resource and Energy Economics, edition 1, volume 3, chapter 18, pages 855-880,
Elsevier.
- Heal, G., 1990. "The Optimal Use Of Exhaustible Resources," Papers fb-_90-10, Columbia - Graduate School of Business.
- Withagen, Cees & B. Asheim, Geir, 1998. "Characterizing sustainability: The converse of Hartwick's rule," Journal of Economic Dynamics and Control, Elsevier, vol. 23(1), pages 159-165, September.
- Hartwick, John M, 1977.
"Intergenerational Equity and the Investing of Rents from Exhaustible Resources,"
American Economic Review, American Economic Association, vol. 67(5), pages 972-974, December.
- John Hartwick, 1976. "Intergenerational Equity and the Investing of Rents from Exhaustible Resources," Working Paper 220, Economics Department, Queen's University.
- Swapan Dasgupta & Tapan Mitra, 1999. "On the Welfare Significance of National Product for Economic Growth and Sustainable Development," The Japanese Economic Review, Japanese Economic Association, vol. 50(4), pages 422-442, December.
- Mitra, Tapan, 2002.
"Intertemporal Equity and Efficient Allocation of Resources,"
Journal of Economic Theory, Elsevier, vol. 107(2), pages 356-376, December.
- Mitra, Tapan, 2000. "Intertemporal Equity and Efficient Allocation of Resources," Working Papers 00-12, Cornell University, Center for Analytic Economics.
- R. M. Solow, 1974.
"Intergenerational Equity and Exhaustible Resources,"
The Review of Economic Studies, Review of Economic Studies Ltd, vol. 41(5), pages 29-45.
- R. M. Solow, 1973. "Intergenerational Equity and Exhaustable Resources," Working papers 103, Massachusetts Institute of Technology (MIT), Department of Economics.
- Kirk Hamilton, 1995. "Sustainable development, the Hartwick rule and optimal growth," Environmental & Resource Economics, Springer;European Association of Environmental and Resource Economists, vol. 5(4), pages 393-411, June.
- repec:bla:scandj:v:88:y:1986:i:1:p:141-49 is not listed on IDEAS
- Mitra, Tapan, 1978. "Efficient growth with exhaustible resources in a neoclassical model," Journal of Economic Theory, Elsevier, vol. 17(1), pages 114-129, February.
- Dasgupta, Swapan & Mitra, Tapan, 1983. "Intergenerational Equity and Efficient Allocation of Exhaustible Resources," International Economic Review, Department of Economics, University of Pennsylvania and Osaka University Institute of Social and Economic Research Association, vol. 24(1), pages 133-153, February.
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Cited by:
- Louis Dupuy & Matthew Agarwala, 2014. "International trade and sustainable development," Chapters, in: Giles Atkinson & Simon Dietz & Eric Neumayer & Matthew Agarwala (ed.), Handbook of Sustainable Development, chapter 25, pages 399-417, Edward Elgar Publishing.
- Abubakar, Attahir Babaji & Muhammad, Mansur & Mensah, Samuel, 2023. "Response of fiscal efforts to oil price dynamics," Resources Policy, Elsevier, vol. 81(C).
- Antony, Jürgen & Klarl, Torben, 2019. "Resource depletion in a Ramsey economy with subsistence consumption, exogenous technical change and capital depreciation: A full characterization," VfS Annual Conference 2019 (Leipzig): 30 Years after the Fall of the Berlin Wall - Democracy and Market Economy 203640, Verein für Socialpolitik / German Economic Association.
- Mitra, Tapan & Asheim, Geir B. & Buchholz, Wolfgang & Withagen, Cees, 2013.
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Journal of Economic Theory, Elsevier, vol. 148(5), pages 2164-2182.
- Tapan, Mitra & Asheim, Geir B. & Buchholz, Wolfgang & Withagen, Cees, 2012. "Characterizing the Sustainability Problem in an Exhaustible Resource Model," Memorandum 08/2012, Oslo University, Department of Economics.
- Tapan Mitra & Gier B Asheim & Wolfgang Buchholz & Cees Withagen, 2012. "Characterizing the sustainability problem in an exhaustible resource model," OxCarre Working Papers 083, Oxford Centre for the Analysis of Resource Rich Economies, University of Oxford.
- Tapan Mitra & Geir B. Asheim & Wolfgang Buchholz & Cees A. Withagen, 2012. "Characterizing the Sustainability Problem in an Exhaustible Resource Model," CESifo Working Paper Series 3758, CESifo.
- Nick Hanley & Louis Dupuy & Eoin McLaughlin, 2015.
"Genuine Savings And Sustainability,"
Journal of Economic Surveys, Wiley Blackwell, vol. 29(4), pages 779-806, September.
- Nick Hanley & Louis Dupuy & Eoin McLaughlin, 2014. "Genuine Savings and Sustainability," Discussion Papers in Environment and Development Economics 2014-09, University of St. Andrews, School of Geography and Sustainable Development.
- Phoebe Koundouri & Georgios I. Papayiannis & Athanasios Yannacopoulos, 2022. "Optimal Control Approaches to Sustainability under Uncertainty," DEOS Working Papers 2215, Athens University of Economics and Business.
- d'Autume, Antoine & Schubert, Katheline, 2008.
"Hartwick's rule and maximin paths when the exhaustible resource has an amenity value,"
Journal of Environmental Economics and Management, Elsevier, vol. 56(3), pages 260-274, November.
- Antoine d'Autume & Katheline Schubert, 2008. "Hartwick's rule and maximin paths when the exhaustible resource has an amenity value," Documents de travail du Centre d'Economie de la Sorbonne v08031, Université Panthéon-Sorbonne (Paris 1), Centre d'Economie de la Sorbonne.
- Antoine d'Autume & Katheline Schubert, 2008. "Hartwick's rule and maximin paths when the exhaustible resource has an amenity value," Université Paris1 Panthéon-Sorbonne (Post-Print and Working Papers) halshs-00275765, HAL.
- Antoine d'Autume & Katheline Schubert, 2008. "Hartwick's rule and maximin paths when the exhaustible resource has an amenity value," Université Paris1 Panthéon-Sorbonne (Post-Print and Working Papers) halshs-00308793, HAL.
- Antoine d'Autume & Katheline Schubert, 2008. "Hartwick's rule and maximin paths when the exhaustible resource has an amenity value," Post-Print halshs-00275765, HAL.
- Antoine d'Autume & Katheline Schubert, 2008. "Hartwick's rule and maximin paths when the exhaustible resource has an amenity value," Post-Print halshs-00308793, HAL.
- Antoine d'Autume & Katheline Schubert, 2008. "Hartwick's rule and maximin paths when the exhaustible resource has an amenity value," PSE-Ecole d'économie de Paris (Postprint) halshs-00308793, HAL.
- Asheim, Geir B. & Hartwick, John M. & Mitra, Tapan, 2021.
"Investment rules and time invariance under population growth,"
Journal of Economic Dynamics and Control, Elsevier, vol. 123(C).
- Geir B. Asheim & John M. Hartwick & Tapan Mitra, 2020. "Investment Rules and Time Invariance under Population Growth," CESifo Working Paper Series 8513, CESifo.
- Geir B. Asheim & Tapan Mitra, 2021.
"Characterizing sustainability in discrete time,"
Economic Theory, Springer;Society for the Advancement of Economic Theory (SAET), vol. 71(2), pages 461-481, March.
- Geir B. Asheim & Tapan Mitra, 2018. "Characterizing Sustainability in Discrete Time," CESifo Working Paper Series 7206, CESifo.
- Yu, Yun & Lei, Yalin, 2017. "China's provincial exhaustible resources rent and produced capital stock—Based on Hartwick's rule," Resources Policy, Elsevier, vol. 52(C), pages 114-121.
- Smulders, Sjak & Withagen, Cees, 2012. "Green growth -- lessons from growth theory," Policy Research Working Paper Series 6230, The World Bank.
- Bazhanov, A., 2011.
"The Dependence of the Potential Sustainability of a Resource Economy on the Initial State: a Comparison of Models Using the Example of Russian Oil Extraction,"
Journal of the New Economic Association, New Economic Association, issue 12, pages 77-100.
- Bazhanov, Andrei, 2011. "The dependence of the potential sustainability of a resource economy on the initial state: a comparison of models using the example of Russian oil extraction," MPRA Paper 35870, University Library of Munich, Germany.
- Bazhanov, Andrei, 2011. "Зависимость Долгосрочного Роста Ресурсной Экономики От Начального Состояния: Сравнение Моделей На Примере Российской Нефтедобычи [The dependence of the potential sustainability of a resource econom," MPRA Paper 35888, University Library of Munich, Germany.
- Bazhanov, Andrei, 2008. "Sustainable growth in a resource-based economy: the extraction-saving relationship," MPRA Paper 12350, University Library of Munich, Germany.
- Khan, M. Ali, 2016. "On a forest as a commodity and on commodification in the discipline of forestry," Forest Policy and Economics, Elsevier, vol. 72(C), pages 7-17.
- Tapan Mitra, 2008.
"On competitive equitable paths under exhaustible resource constraints: The case of a growing population,"
International Journal of Economic Theory, The International Society for Economic Theory, vol. 4(1), pages 53-76, March.
- Mitra, Tapan, 2007. "On Competitive Equitable Paths under Exhaustible Resource Constraints: The Case of a Growing Population," Working Papers 07-05, Cornell University, Center for Analytic Economics.
- Asheim, Geir B. & Hartwick, John M. & Yamaguchi, Rintaro, 2023. "Sustainable per capita consumption under population growth," Resource and Energy Economics, Elsevier, vol. 73(C).
- Asheim, Geir B. & Buchholz, Wolfgang & Hartwick, John M. & Mitra, Tapan & Withagen, Cees, 2007.
"Constant savings rates and quasi-arithmetic population growth under exhaustible resource constraints,"
Journal of Environmental Economics and Management, Elsevier, vol. 53(2), pages 213-229, March.
- Geir B. Asheim & Wolfgang Buchholz & John M. Hartwick & Tapan Mitra & Cees A. Withagen, 2005. "Constant Savings Rates and Quasi-Arithmetic Population Growth under Exhaustible Resource Constraints," CESifo Working Paper Series 1573, CESifo.
- Asheim, Geir B. & Buchholz, Wolfgang & Hartwick, John M. & Mitra, Tapan & Withagen, Cees, 2005. "Constant savings rates and quasi-arithmetic population growth under exhaustible resource constraints," Memorandum 23/2005, Oslo University, Department of Economics.
- Rintaro Yamaguchi, 2021. "Genuine Savings and Sustainability with Resource Diffusion," Environmental & Resource Economics, Springer;European Association of Environmental and Resource Economists, vol. 80(2), pages 451-471, October.
- Antony, Jürgen & Klarl, Torben, 2023.
"Subsistence consumption and natural resource depletion: Can resource-rich low-income countries realize sustainable consumption paths?,"
Journal of Macroeconomics, Elsevier, vol. 77(C).
- Jürgen Antony & Torben Klarl, 2023. "Subsistence Consumption and Natural Resource Depletion: Can resource-rich low-income countries realize sustainable consumption paths?," Bremen Papers on Economics & Innovation 2302, University of Bremen, Faculty of Business Studies and Economics.
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More about this item
JEL classification:
- D90 - Microeconomics - - Micro-Based Behavioral Economics - - - General
- O11 - Economic Development, Innovation, Technological Change, and Growth - - Economic Development - - - Macroeconomic Analyses of Economic Development
- O41 - Economic Development, Innovation, Technological Change, and Growth - - Economic Growth and Aggregate Productivity - - - One, Two, and Multisector Growth Models
- Q32 - Agricultural and Natural Resource Economics; Environmental and Ecological Economics - - Nonrenewable Resources and Conservation - - - Exhaustible Resources and Economic Development
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