The Social Discount Rate

Abstract: The social discount rate measures the rate at which a society would be willing to trade present for future consumption. As such it is one of the most critical inputs needed for cost-benefit analysis. This paper presents estimates of the social discount rates for nine Latin American countries. It is argued that if the recent track record in terms of growth in the region is indicative of future performance, estimates of the social discount rate would be in the 3-4 percent range. However, to the extent that the region improves on its past performance, the social discount rate to be used in the evaluation of projects would increase to the 5-7 percent range. The paper also argues that if the social planner gives a similar chance to the low and high growth scenario, the discount rate should be dependent on the horizon of the project, declining from 4.4 percent for a 25-year horizon to less than 4 percent for a 100-year horizon.

The social discount rate measures the rate at which a society would be willing to trade present for future consumption. As such it is one of the most critical inputs needed for cost-benefit analysis. This paper presents estimates of the social discount rates for nine Latin American countries. It is argued that if the recent track record in terms of growth in the region is indicative of future performance, estimates of the social discount rate would be in the 3-4 percent range. However, to the extent that the region improves on its past performance, the social discount rate to be used in the evaluation of projects would increase to the 5-7 percent range. The paper also argues that if the social planner gives a similar chance to the low and high growth scenario, the discount rate should be dependent on the horizon of the project, declining from 4.4 percent for a 25-year horizon to less than 4 percent for a 100-year horizon.

The social cost of carbon (SC-CO2) is an economic metric intended to provide a comprehensive estimate of the net damages - that is, the monetized value of the net impacts, both negative and positive - from the global climate change that results from a small (1-metric ton) increase in carbon-dioxide (CO2) emissions. Under Executive Orders regarding regulatory impact analysis and as required by a court ruling, the U.S. government has since 2008 used estimates of the SC-CO2 in federal rulemakings to value the costs and benefits associated with changes in CO2 emissions. In 2010, the Interagency Working Group on the Social Cost of Greenhouse Gases (IWG) developed a methodology for estimating the SC-CO2 across a range of assumptions about future socioeconomic and physical earth systems. Valuing Climate Changes examines potential approaches, along with their relative merits and challenges, for a comprehensive update to the current methodology. This publication also recommends near- and longer-term research priorities to ensure that the SC- CO2 estimates reflect the best available science.

Today, the judge, the citizen, the politician, and the entrepreneur are concerned with the sustainability of our development.

The full effects of decisions made today about many environmental policies -including climate change and nuclear waste- will not be felt for many years. For issues with long-term ramifications, analysts often employ discount rates to compare present and future costs and benefits. This is reasonable, and discounting has become a procedure that raises few objections. But are the methods appropriate for measuring costs and benefits for decisions that will have impacts 20 to 30 years from now the right ones to employ for a future that lies 200 to 300 years in the future? This landmark book argues that methods reasonable for measuring gains and losses for a generation into the future may not be appropriate when applied to a longer span of time. Paul Portney and John Weyant have assembled some of the world's foremost economists to reconsider the purpose, ethical implications, and application of discounting in light of recent research and current policy concerns. These experts note reasons why conventional calculations involved in discounting are undermined when considering costs and benefits in the distant future, including uncertainty about the values and preferences of future generations, and uncertainties about available technologies. Rather than simply disassemble current methodologies, the contributors examine innovations that will make discounting a more compelling tool for policy choices that influence the distant future. They discuss the combination of a high shout-term with a low long-term diescount rate, explore discounting according to more than one set of anticipated preferences for the future, and outline alternatives involving simultaneous consideration of valuation, discounting and political acceptability.

This book presents a comprehensive account of the energy and environmental security perspectives of the developing countries. To address the subject comprehensively, it covers four geographically diverse clusters of developing countries from across the world. The regions particularly focused on are: South Asia, South East Asia, Sub Sahara Africa, and Latin America. It is a valuable contribution to the debate, and policy and research activities around the subjects of energy and environmental security in the developing countries and beyond. The book covers the interwoven subjects of energy security and environmental security in the context of developing countries for the first time. It discusses the latest dimensions, challenges, and solutions around taking into account technical, economic, social, and policy perspectives. It incorporates up-to-date data, case studies, and comparative assessment. This edited book has contributions from established as well as emerging scholars from around the world. It benefits a wide range of stakeholders from the fields of energy, environment, and sustainable development. It is of help to academics, researchers, and analysts in these fields besides having appeal for policymakers, and national and international developmental organizations. It also helps developing countries to learn from each other’s experiences.

This urgent and eye-opening book makes the case that protecting humanity's future is the central challenge of our time. If all goes well, human history is just beginning. Our species could survive for billions of years - enough time to end disease, poverty, and injustice, and to flourish in ways unimaginable today. But this vast future is at risk. With the advent of nuclear weapons, humanity entered a new age, where we face existential catastrophes - those from which we could never come back. Since then, these dangers have only multiplied, from climate change to engineered pathogens and artificial intelligence. If we do not act fast to reach a place of safety, it will soon be too late. Drawing on over a decade of research, The Precipice explores the cutting-edge science behind the risks we face. It puts them in the context of the greater story of humanity: showing how ending these risks is among the most pressing moral issues of our time. And it points the way forward, to the actions and strategies that can safeguard humanity. An Oxford philosopher committed to putting ideas into action, Toby Ord has advised the US National Intelligence Council, the UK Prime Minister's Office, and the World Bank on the biggest questions facing humanity. In The Precipice, he offers a startling reassessment of human history, the future we are failing to protect, and the steps we must take to ensure that our generation is not the last. "A book that seems made for the present moment." —New Yorker

The collection of papers on social project evaluation.