Global Warming Effects Around the World

DeBilt, the Netherlands

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People (Health)

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Temperature (Air)

People (Water use)

Heat exhaustion overcomes bicyclist and others on a hot day in Amsterdam

Cities in the Netherlands and throughout Europe suffered through an unprecedented and deadly heat wave in the summer of 2003. Unless we make deep and swift cuts in our global warming emissions, a similar heat wave could hit Europe every other year by the end of this century, on average. Here, Amsterdam residents take a break from the scorching heat.1

Key Facts

Thousands of people across Europe died from heat-related causes in the sweltering summer of 2003—the hottest in at least 500 years.2 If our heat-trapping emissions continue to rise at current rates,26 a summer like the one in 2003 could be considered ordinary by the end of the century. Extreme hot and humid heat waves of the future may even approach the limits of what the human body can endure.16

  • In the Netherlands, hundreds of people died during a two-week extreme heat wave in August 2003.6 The De Bilt weather station near Utrecht recorded the summer's highest temperature.6
  • Belgium, the Czech Republic, Germany, Italy, Portugal, Spain, Switzerland, and the United Kingdom also reported above-average death rates.7,8,9,10,11,12,13
  • Unless we make deep and swift cuts in our heat-trapping emissions,26 Europe could experience a similar heat wave every other year by the end of this century, on average.23


In Europe, the summer of 2003 was the hottest in at least 500 years.2 Thousands of people across the continent died from heat-related causes.2 The unusually hot weather began in June and escalated to a record-breaking two-week heat wave in August. Temperatures that month were 12.6° F (7° C) above average,3 and peak temperatures exceeded 104° F (40° C).4,5

In the Netherlands, where summers are usually mild, the ancient city of Utrecht was particularly hard-hit. While the De Bilt weather station near Utrecht recorded a high of "only" 95° F (35° C),6 1,000 to 1,400 more people died from the heat than in an average summer, and the two-week stretch of extreme heat in August claimed 400 to 500 lives.6

Belgium, the Czech Republic, Germany, Italy, Portugal, Spain, Switzerland, and the United Kingdom also reported above-average death rates.7,8,9,10,11,12,13 Heat-related deaths across Europe totaled 35,00014 to 50,000 that summer.15

Humans can overheat if core body temperatures much above 98.6° F (37° C) are sustained.16 Normally, when skin temperatures is somewhat cooler than 98.6° F (37° C), the body loses its metabolically generated heat by conducting that heat outward from the core.7 Extremely hot and humid conditions, however, can make it difficult to keep this heat balance maintained.16 Extreme heat can be particularly dangerous to old, young, or frail people; to those suffering from cardiovascular, respiratory, or diabetic disease; and to lower-income people who do not have well-insulated homes or air-conditioning.17,18

As if sweltering heat weren't bad enough, Europeans also suffered through a higher-than-normal number of days with dangerous smog levels that year.6 Smog—with ground-level ozone as the main component—forms when sunlight reacts with chemicals such as volatile organic compounds, carbon monoxide, nitrogen oxides, and water vapor. Higher temperatures enhance the chemical reaction, so smog levels can rise even if emissions from vehicle tailpipes or coal-fired power plants remain the same.6,19

Higher air pollution levels can compound the effects of excessive heat, and vice versa.20 Some of the heat-related deaths in 2003 may also have been smog-related—including one-quarter to three-fifths of the excess deaths in the Netherlands.6

Along with the hot summer, annual precipitation for 2003 was as much as 12 inches (300 millimeters) below normal, leaving most of Europe in a drought.21 Damages to the agricultural sector were estimated at more than U.S. $16 billion (more than €13 billion).3,21 Many areas saw an increase in wildfires, while low water levels in major rivers led to problems ranging from irrigating crops to cooling power plants.4,21,22

What the Future Holds

While the 2003 heat wave was unusual in today's climate,23 Europe is highly likely to face even hotter summers more often in coming decades.24 Scientists estimate that human activities have already at least doubled the risk of an extreme heat wave.25

Unless we make deep and swift cuts in our heat-trapping emissions,26 Europe could experience a heat wave similar to the one in 2003 every other year by the end of this century.23 A summer like that of 2003 would be considered ordinary4—or even cool.25 Summers in central Europe are expected to feel like those in southern European today.27

Climatic variability in summer is projected to increase, with southern Europe experiencing more heat, less precipitation, and more frequent droughts—yet heavier rainstorms when it does rain.23 Northern Europe can expect more overall precipitation.21 Smog is also expected to rise—unless we reduce our use of fossil fuels.28,29,30,31

Ironically, people in cold regions can be most vulnerable to heat waves, because they are not acclimated to extremely hot weather, and because buildings designed for cold climates may not offer protection against extreme heat and high humidity.32 The elderly and those who do not have access to air-conditioning will likely be less resilient in the face of more frequent heat waves.19

One study estimates that there are likely to be places on Earth where unprotected humans without cooling mechanisms, such as air conditioning, would die in less than six hours if global average surface temperature rises by about 12.6° F (7° C).16 With warming of 19.8-21.6° F (11-12° C), this same study projects that regions where approximately half of the world's people now live could become intolerable.7

Even as Europeans adapt to hotter summers, rising numbers of heat-related deaths are likely.33,34 The 2003 heat wave shows that even high-income countries such as the Netherlands are not currently positioned to cope with extreme weather19—a troubling prospect, as research suggests that by as early as the 2040s, if we continue on the current high emissions path, about half the summers in southern Europe are likely to be as warm as the record-breaking heat wave of 2003.26,35



  1. Photograph courtesy of Michael Schipper.
  2. Luterbacher, J., D. Dietrich, E. Xoplaki, M. Grosjean, and H. Wanner. 2004. European seasonal and annual temperature variability, trends, and extremes since 1500. Science 303:1499-1503.
  3. Fink, A.H., T. Brücher, A. Krüger, G.C. Leckebusch, J.G. Pinto, and U. Ulbrich. 2004. The 2003 European summer heatwaves and drought: Synoptic diagnosis and impact. Weather 59:209-216.
  4. Beniston, M., and H.F. Díaz. 2004. The 2003 heatwave as an example of summers in a greenhouse climate? Observations and climate model simulations for Basel, Switzerland. Global and Planetary Change 44:73-81.
  5. André, J.-C., M. Déqué, P. Rogel, and S. Planton. 2004. The 2003 summer heatwave and its seasonal forecasting. Comptes Rendus Geosciences 336:491-503.
  6. Fischer, P.H., B. Brunekreef, and E. Lebret. 2004. Air pollution related deaths during the 2003 heat wave in the Netherlands. Atmospheric Environment 38:1083-1085.
  7. Hemon, D., and E. Jougla. 2004. La canicule du mois d'aôut 2003 en France [The heatwave in France in August 2003]. Revue d' Epidémiologie et de Santé Publique 52:3-5.
  8. Martinez-Navarro, F., F. Simon-Soria, and G. Lopez-Abente. 2004. Valoracion del impacto de la ola de calor del verano de 2003 sobre la mortalidad [Evaluation of the impact of the heatwave in the summer of 2003 on mortality]. Gaceta Sanitaria 18(suppl 1):250-258.
  9. Michelozzi, P., F. de Donato, G. Accetta, F. Forastiere, M. D'Ovido, and L.S. Kalk- Stein. 2004. Impact of heat waves on mortality: Rome, Italy, June-August 2003. Journal of the American Medical Association 291:2537-2538.
  10. Vandentorren, S., F. Suzan, S. Medina, M. Pascal, A. Maulpoix, J.-C. Cohen, and M. Ledrans. 2004. Mortality in 13 French cities during the August 2003 heatwave. American Journal of Public Health 94:1518-1520.
  11. Conti, S., P. Meli, G. Minelli, R. Solimini, V. Toccaceli, M. Vichi, C. Beltrano, and L. Perini. 2005. Epidemiologic study of mortality during the summer 2003 heat wave in Italy. Environmental Research 98:390-399.
  12. Grize, L., A. Huss, O. Thommen, C. Schindler, and C. Braun-Fahrländer. 2005. Heat wave 2003 and mortality in Switzerland. Swiss Medical Weekly 135:200-205.
  13. Johnson, H., R.S. Kovats, G.R. McGregor, J.R. Stedman, M. Gibbs, H. Walton, L. Cook, and E. Black. 2005. The impact of the 2003 heatwave on mortality and hospital admissions in England. Health Statistics Quarterly 25:6-12.
  14. Kosatsky, T. 2005. The 2003 European heatwave. Eurosurveillance 10:148-149.
  15. Brücker, G. 2005. Vulnerable populations: Lessons learnt from the summer 2003 heat waves in Europe. Eurosurveillance 10(7). Online at ViewArticle.aspx? ArticleId=551. Accessed May 12, 2010.
  16. Sherwood, S.C., and M. Huber. 2010. An adaptability limit to climate change due to heat stress. Proceedings of the National Academy of Sciences. Online at cgi/ doi/ 10.1073/ pnas.0913352107.
  17. U.S. Global Change Research Program. 2009. Global climate change impacts in the United States. Edited by T.R. Karl, J.M. Melillo, and T.C. Peterson. Cambridge University Press.
  18. Congressional Black Caucus Foundation. 2004. African Americans and climate change: an unequal burden. Washington, DC.
  19. Confalonieri, U., B. Menne, R. Akhtar, K.L. Ebi, M. Hauengue, R.S. Kovats, B. Revich, and A. Woodward. 2007. Human health. In: Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, pp. 391-431.
  20. Katsouyanni, K., A. Pantazopoulou, G. Touloumi, I. Tselepidaki, K. Moustris, D.Asimakopoulos, G. Poulopoulou, and D. Trichopoulos. 1993. Evidence for interaction between air pollution and high temperature in the causation of excess mortality. Archives of Environmental Health 48(4):235-242.
  21. Alcamo, J., J.M. Moreno, B. Nováky, M. Bindi, R. Corobov, R.J.N. Devoy, C. Giannakopoulos, E. Martin, J.E. Olesen, and A. Shvidenko. 2007. Europe. In: Climate change 2007: Impacts, adaptation and vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Edited by M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden, and C.E. Hanson. Cambridge University Press, pp. 541-580.
  22. Zebisch, M., T. Grothmann, D. Schröter, C. Hasse, U. Fritsch, and W. Cramer. 2005. Climate change in Germany: Vulnerability and adaptation of climate sensitive sectors. Umweltbundesamt Climate Change, October (UFOPLAN 201 41 253).
  23. Schär, C., and G. Jendritzky. 2004. Climate change: Hot news from summer 2003. Nature 432:559-560.
  24. Meehl, G.A., and C. Tebaldi. 2004. More intense, more frequent, and longer lasting heatwaves in the 21st Century. Science 305:994-997.
  25. Stott, P.A., D.A. Stone, and M.R. Allen. 2004. Human contribution to the European heatwave of 2003. Nature 432:610-614.
  26. The emissions scenario referred to here is the high-emissions path known as A2 from the Intergovernmental Panel on Climate Change.
  27. Beniston, M., D.B. Stephenson, O.B. Christensen, C.A.T. Ferro, C. Frei, S. Goyette, K. Halsnaes, T. Holt, K. Jylhä, B. Koffi, J. Palutikof, R. Schöll, T. Semmler, and K. Woth. 2007. Future extreme events in European climate: An exploration of regional climate model projections. Climatic Change 81:S71-S95.
  28. Hennessy, E. 2002. Air pollution and short term mortality. British Medical Journal 324:691-692.
  29. Revich, B.A., and D.A. Shaposhnikov. 2004. High air temperature in cities is real hazard to human health. In: Climate change and public health in Russia in the XXI century. Edited by N.F. Izmerov, B.A. Revich, and E.I. Korenberg. Proceedings of a workshop, April 56, 2004. Moscow: Adamant, 175184.
  30. Stedman, J.R. 2004. The predicted number of air pollution related deaths in the UK during the August 2003 heatwave. Atmospheric Environment 38:10871090.
  31. Kislitsin, V., S. Novikov, and N. Skvortsova. 2005. Moscow smog of summer 2002: Evaluation of adverse health effects. In: Extreme weather events and public health responses. Edited by W. Kirch, B. Menne, and R. Bertollini. Berlin: Springer-Verlag, pp. 255262.
  32. U.S. Environmental Protection Agency. 2006. Excessive heat events guidebook. EPA 430-B-06-005. Washington, DC: Office of Atmospheric Programs.
  33. Casimiro, E., and J.M. Calheiros. 2002. Human health. In: Climate change in Portugal: Scenarios, impacts, and adaptation measures. Edited by F.D. Santos, K. Forbes, and R. Moita. Lisbon: Gradiva, pp. 245300.
  34. U.K. Department of Health. 2002. Chapter 12: Europe. In: Health effects of climate change in the UK: Report of the expert advisory group on climate change and health. London.
  35. Jones, G.S. P.A. Stott, and N. Christidis. 2008. Human contribution to rapidly increasing frequency of very warm Northern Hemisphere summers, Journal of Geophysical Research 113. D02109, doi:10.1029/2007JD008914
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