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Climate Change and Global Health: Quantifying a Growing Ethical Crisis


Climate change, as an environmental hazard operating at the global scale, poses a unique and “involuntary exposure” to many societies, and therefore represents possibly the largest health inequity of our time. According to statistics from the World Health Organization (WHO), regions or populations already experiencing the most increase in diseases attributable to temperature rise in the past 30 years ironically contain those populations least responsible for causing greenhouse gas warming of the planet. Average global carbon emissions approximate one metric ton per year (tC/yr) per person. In 2004, United States per capita emissions neared 6 tC/yr (with Canada and Australia not far behind), and Japan and Western European countries range from 2 to 5 tC/yr per capita. Yet developing countries’ per capita emissions approximate 0.6 tC/yr, and more than 50 countries are below 0.2 tC/yr (or 30-fold less than an average American). This imbalance between populations suffering from an increase in climate-sensitive diseases versus those nations producing greenhouse gases that cause global warming can be quantified using a “natural debt” index, which is the cumulative depleted CO2 emissions per capita. This is a better representation of the responsibility for current warming than a single year’s emissions. By this measure, for example, the relative responsibilities of the U.S. in relation to those of India or China is nearly double that using an index of current emissions, although it does not greatly change the relationship between India and China. Rich countries like the U.S. have caused much more of today’s warming than poor ones, which have not been emitting at significant levels for many years yet, no matter what current emissions indicate. Along with taking necessary measures to reduce the extent of global warming and the associated impacts, society also needs to pursue equitable solutions that first protect the most vulnerable population groups; be they defined by demographics, income, or location. For example, according to the WHO, 88% of the disease burden attributable to climate change afflicts children under age 5 (obviously an innocent and “nonconsenting” segment of the population), presenting another major axis of inequity. Not only is the health burden from climate change itself greatest among the world’s poor, but some of the major mitigation approaches to reduce the degree of warming may produce negative side effects disproportionately among the poor, for example, competition for land from biofuels creating pressure on food prices. Of course, in today’s globalized world, eventually all nations will share some risk, but underserved populations will suffer first and most strongly from climate change. Moreover, growing recognition that society faces a nonlinear and potentially irreversible threat has deep ethical implications about humanity’s stewardship of the planet that affect both rich and poor.

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  • Baer P, Harte J, et al. (2000) Equity and greenhouse gas responsibility. Science 289(5488):2287

    Article  CAS  Google Scholar 

  • Boddiger D (2007) Boosting biofuel crops could threaten food security. Lancet 370:923–924

    Article  Google Scholar 

  • Berndesa G, Hoogwijkb M, van den Broek R (2003) The contribution of biomass in the future global energy supply: a review of 17 studies. Biomass and Bioenergy 25:1–28

    Article  Google Scholar 

  • Besser LM, Dannenberg AL (2005) Walking to public transit: steps to help meet physical activity recommendations. American Journal of Preventive Medicine 29(4):273–280

    Article  Google Scholar 

  • Department of Transportation (DOT) (2001) Summary Statistics on Demographic Characteristics and Total Travel, 1969, 1977, 1983, 1990, 1995 NPTS and 2001 NHTS

  • Ebi KL, Woodruff R, von Hildebrand A, Corvalan C (2007). Climate change-related health impacts in the Hindu Kush-Himalayas. EcoHealth 4:264–270

    Article  Google Scholar 

  • Ezzati M, Lopez AD, Rodgers AA. Murray CJL (editors) (2004) Comparative Quantification of Health Risks: Global and Regional Burden of Disease Due to Selected Major Risk Factors, Geneva: World Health Organization, 2 vols

  • Fearnside PM, Laurance WF (2003) Comment on “Determination of deforestation rates of the world’s humid tropical forests”. Science 299(5609):1015

    Article  Google Scholar 

  • Foley JA, Defries R, Asner GP, Barford C, Bonan G, Carpenter SR, et al. (2005) Global consequences of land use. Science 309(5734):570–574

    Article  CAS  Google Scholar 

  • Ford JD, Smit B, Wandel J, MacDonald J. (2006) Vulnerability to climate change in Igloolik, Nunavut: what we can learn from the past and present. Polar Record 42(221):127–138

    Article  Google Scholar 

  • Frumkin H, Frank LD, Jackson R (2004) Urban Sprawl and Public Health: Designing, Planning and Building for Healthy Communities, Washington, DC: Island Press

    Google Scholar 

  • Green D, Smith KR (2002) Implications of graduation: Why developing countries will never produce more greenhouse gases than developed countries. Journal of Energy and Development 28(1):15–40

    Google Scholar 

  • Gross J (2002) The severe impact of climate change on developing countries. Medicine and Global Survival 7(2):96–100

    Google Scholar 

  • Hill J, Nelson E, Tilman D, Polasky S, Tiffany D (2006) Environmental, economic, and energetic costs and benefits of biodiesel and ethanol biofuels. Proceedings of the National Academy of Sciences of the United States of America 103:11206–11210

    Article  CAS  Google Scholar 

  • Houghton RA (2007) Balancing the global carbon budget. Annual Review of Earth and Planetary Science 35:313–347

    Article  CAS  Google Scholar 

  • Hundley JC, Kilgo PD, Miller PR, Chang MC, Hensberry RA, Meredith JW, et al. (2004) Non-helmeted motorcyclists: a burden to society? A study using the National Trauma Data Bank. Journal of Trauma 57(5):944–949

    Article  Google Scholar 

  • Joos F, Bruno M, Fink R, Siegenthaler U, Stocker T, Le Quéré C, Sarmiento JL . (1996) An efficient and accurate representation of complex oceanic and biospheric models of anthropogenic carbon uptake. Tellus Series B: Chemical and Physical Meteorology 48B:397–417

    Article  CAS  Google Scholar 

  • Marland G, Boden TA, Andres RJ (2007) Global, Regional, and National Fossil Fuel CO2 Emissions. In: Trends: A Compendium of Data on Global Change. Carbon Dioxide Information Analysis Center, Oak Ridge, TN: Oak Ridge National Laboratory, U.S. Department of Energy

  • Maylaert MS, Cohen C, Pinguelli Rosa L, Santos Pereira A (2004) Equity, responsibility and climate change. Climate Research 28:89–92

    Article  Google Scholar 

  • McMichael A, Campbell-Lendrum D, et al. (2004) Climate Change. In: Ezzati M, et al. (editors) Comparative Quantification of Health Risks: Global and Regional Burden of Disease Due to Selected Major Risk Factors, Geneva: World Health Organization, vol 2, pp 1543-1649

  • Naylor R, Liska X, et al. (2007) Ripple effects of crop-based biofuels on global food security and the environment. Environment

  • Nepstad DC, Stickler CM, Almeida OT (2006) Globalization of the Amazon soy and beef industries: opportunities for conservation. Conservation Biology 20(6):1595–1603

    Article  Google Scholar 

  • Patz JA, Kovats RS (2002) Hotspots in climate change and human health. BMJ 325(7372):1094–1098

    Article  Google Scholar 

  • Patz JA, Olson SH (2006) Climate change and health: global to local influences on disease risk. Annals of Tropical Medicine and Parasitology 100(5–6):535–549

    Article  CAS  Google Scholar 

  • Patz JA, Campbell-Lendrum D, Holloway T, Foley JA (2005) Impact of regional climate change on human health. Nature 438:310–317

    Article  CAS  Google Scholar 

  • Patz JA, Campbell-Lendrum D, Gibbs H, Woodruff R (2007) Health impact assessment of global climate change: expanding upon comparative risk assessment approaches for policy making. Annual Reviews in Public Health 28:

  • Sachs J, Malaney P (2002) The economic and social burden of malaria. Nature 415(6872):680–685

    Article  CAS  Google Scholar 

  • Schneider SH, Lane J (2005) Dangers and thresholds in climate change and the implications for justices. In: Adger WN (ed) Justice in Adaptation to Climate Change, Cambridge: Cambridge Univ. Press

  • Smith KR (1990) The risk transition. International Environmental Affairs 2(3):227–251

    Google Scholar 

  • sSmith KR (1991) Allocating responsibility for global warming: The Natural Debt index. Ambio 20(2):95–96

    Google Scholar 

  • Smith KR (1996) The Natural Debt: North and South. In: Giambelluca T, Henderson-Sellers A (editors) Climate Change: Developing Southern Hemisphere Perspectives, New York: Wiley & Sons, chap 16, pp 423–448

  • Smith KR, Ezzati M (2005) How environmental health risks change with development: The Epidemiologic and Environmental Risk Transitions revisited.” Annual Review of Energy and Resources 30:291–333

    Article  Google Scholar 

  • Thomas DSG, Twyman C (2005) Equity and justice in climate change adaptation amongst natural-resource-dependent societies. Global Environmental Change-Human and Policy Dimensions 15(2):115–124

    Article  Google Scholar 

  • United Nations-Energy (2007) Sustainable Bioenergy: A Framework for Decision Makers

  • WHO (2002) The World Health Report 2002, Geneva: World Health Organization

    Google Scholar 

  • Wilkinson P, Smith KR, Joffe M, Haines A (2007a) A global perspective on energy: Health effects and injustices, Series on Energy and Health #1. Lancet 370:5–18

    Google Scholar 

  • Wilkinson P, Smith KR, Beevers, Tonne C, Oreszcayn T (2007b) Energy, energy efficiency, and the built environment, Series on Energy and Health #4. Lancet 370:42–54

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The authors thank Aaron Ruesch and Sarah Olson from the University of Wisconsin Center for Sustainability and the Global Environment (SAGE) for creating the CO2 emissions and disease burden maps, respectively, and Tony McMichael and Diarmid Campbell-Lendrum for statistics from the World Health Organization Global Burden of Disease project on climate change. Partial funding support for this article came from the Center for World Affairs and the Global Economy (WAGE) of the University of Wisconsin–Madison.

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Correspondence to Jonathan A. Patz.

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Patz, J.A., Gibbs, H.K., Foley, J.A. et al. Climate Change and Global Health: Quantifying a Growing Ethical Crisis. EcoHealth 4, 397–405 (2007).

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  • biofuels
  • built environment
  • cobenefits
  • CO2 emissions
  • food security
  • global warming
  • equity
  • natural debt
  • malaria
  • malnutrition