Perspectives

www.thelancet.com Vol 384 November 29, 2014 e60

BookAre things getting better?Are global problems getting better? This is the question addressed by Bjørn Lomborg and the Copenhagen Consensus Center (CCC) in How Much Have Global Problems Cost the World? A Scorecard from 1900 to 2050. In this departure from CCC’s usual research, CCC economists take stock of the world’s problems rather than their solutions. Included in the book are analyses of a diverse set of ten global challenges: air pollution, armed confl icts, climate change, ecosystem loss, education, gender equality, health, malnutrition, trade barriers, and water and sanitation. Each of these challenges is addressed in a separate chapter, with the unifying objective being to measure costs associated with each problem from 1900 through 2050.

Although each chapter’s authors make an impressive eff ort to quantify costs, it seems clear from the outset that the project’s scope is too grand for the data available to support its conclusions. Nearly every chapter is hampered by data limitations that force the authors to exclude important costs or model global and regional costs using data from a handful of countries. There is also a degree of methodological inconsistency across the book. Some chapters base their estimates on premature mortality, whereas others include both mortality and morbidity. Still other chapters focus on the opportunity costs of government expenditures, time, or lost wages. In addition to this, some chapters adopt a net costing approach whereby both the costs and benefits are incorporated into the analysis, whereas other contributors simply estimate costs. Thus, comparison of costs across chapters is not really possible. Nonetheless, the contributors come to some interesting conclusions. When measured as a percentage of gross domestic product

(GDP) there are marked reductions in the costs for all challenges except climate change and trade barriers. When assessed together, these patterns lead to the bold statement made in the introduction that “things are getting better”.

This optimistic sentiment might be overstated. The reported reductions in costs are largely driven by the choice of metric. If measured in per capita terms, rather than as a percentage of GDP, costs show less promising, and in many cases opposite, trends.

Costs associated with premature mortality estimated in the health chapter, for example, decline from 32% of global GDP in 1900 to 5% of GDP in 2050. This extraordinary reduction has been most pronounced in low-income and middle-income countries. On the other hand, when measured in per capita terms these costs are expected to grow three-fold. Back-of-the-envelope calculations for many of the ten challenges show that per capita costs are increasing. It is only when costs are considered relative to GDP (which is predicted to grow substantially) that the stark reductions are observed.

Measuring costs as a share of GDP has some economic precedent, since it considers the burden of a challenge relative to the ability to aff ord the burden. This approach has the advantage of normalising costs estimated for different geographies and time periods. However, this metric has limitations. First, it masks the aforementioned increases in per capita costs. When measured as a share of GDP only costs that grow faster than

GDP will increase over time. Second, measuring costs as a percentage of GDP offers little insight to policy makers who are primarily concerned with the relative size of costs and benefi ts, and not costs and ability to pay.

These measurement debates aside, this book is an ambitious fi rst attempt at a daunting task. To the degree that it can be a starting point for ongoing and improved research, the contributors should be encouraged. These cost estimates and the accompanying discussion of each challenge are both interesting and informative. Still, three important questions remain. First, how much have global problems cost the world? From the start of the book the authors are clear that this question cannot be answered because the defi nitions, data, assumptions, and methods across the ten challenges are too disparate to allow for aggregation. Second, is this book an objective scorecard from 1900 to 2050? We were not convinced: the same reasons that prevent aggregation prevent comparisons of each problem’s costs. Third, is the optimism of the introduction warranted—are things getting better? Here, we are less certain. One’s approach to this question is certainly dependent on a host of choices related to which problems to assess, researchers to query, assumptions to make, models to use, and metrics to evaluate. How Much Have Global Problems Cost the World? provides one set of answers to these questions and concludes with an assertion that things are getting better. We encourage ambitious readers to dive in and decide for themselves.

Joseph L Dieleman, James I PriceInstitute for Health Metrics and Evaluation, Seattle, WA 91803, USA (JLD); and Department of Economics, Brock University, Canada (JIP)dieleman@uw.edu

How Much Have Global Problems Cost the World? A Scorecard from 1900 to 2050Bjørn Lomborg, ed. Cambridge University Press. Pp 401. US$34·99. ISBN 9781107679337“How Much Have Global Problems

Cost the World? provides one set of answers to these questions and concludes with an assertion that things are getting better.”