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Human Health Effects


Studies have shown a close link between local climate characteristics and the occurrence of disease. We also know that many environmental conditions affect human health, and climate and weather can greatly these conditions.

It has been estimated by the World Health Organization that climate changes have contributed to 150,000 deaths and 5 million illnesses each year and that one-fourth of the world’s diseases is caused by the environmentally based contamination of air, water, soil, and food. Increases in temperatures and the resulting consequences have led to loss of life and decreased well-being of hundreds of thousands of people worldwide.

Most of the burden is carried by the world’s poorest people. Increased deaths and disease from malnutrition, diarrhea, malaria, heat waves, and floods occur in regions with little healthcare and poor emergency resources.

Consider the following when assessing the data for climate-related health issues:

  • As populated areas become hotter, residents must adapt. The very young, the elderly, and people already stressed by disease and/or poverty are the most vulnerable.
  • As temperatures over a region increase, the populations of disease-carrying insects may increase. Disease vectors, such as mosquitoes and ticks, increase along with the diseases they carry. Insect vectors are less likely to die if seasonal weather is not cold enough to kill them.
  • Heat-related illnesses and deaths occur more frequently as the number of heat waves increase, especially in urban areas. Poor people who cannot afford air conditioning to escape the heat are most affected by heat waves.
  • Higher temperatures increase ozone in the troposphere. Higher concentrations of ozone increase cardiovascular and pulmonary illnesses.
  • Waterborne pathogens increase in areas hit by increased numbers of floods.
  • Allergic diseases may increase with higher temperatures and longer growing seasons.
  • It is estimated that up to 35,000 people in five countries died because of the 2003 European heat wave when temperatures were 20-30 percent above average.
  • A July 1995 heat wave in the Chicago area killed more than 700 people.

As you work through this problem, use the related links and background information provided in the module to consider the interrelated aspects of potential global climate change. Human health may be affected by each aspect. A solid understanding of the mechanisms underlying the connections will allow for a more comprehensive report.