US National Assessment of the Potential Consequences of Climate Variability and Change
A detailed overview of the consequences of climate change and mechanisms for adaptation, published in 2000

USGCRP logo and link to home
Updated 6 September 2008

Climate Change Impacts
on the United States
The Potential Consequences
of Climate Variability and Change
Images from Foundation Report
Sector: Health

US Global Change Research Program
Submitted to the President and to Congress in November 2000

See also:

Image Title Caption Source Larger and/or  Higher Resolution Files

Figure 1. Potential Health Effects of Climate Variability and Change

*Moderating influences include non-climate factors that affect climate-related health outcomes, such as: population growth and demographic change; standards of living; access to health care; improvements in health care; and public health infrastructure.

**Adaptation measures include actions to reduce risks of adverse health outcomes, such as: vaccination programs, disease surveillance, monitoring; use of protective technologies(e.g., air conditioning, pesticides, water filtration/treatment); use of climate forecasts; and development of weather warning systems; emergency management and disaster preparedness programs; and public education.

Patz et al., 2000 Medium JPEG (89 kilobytes)

Medium JPEG Optimized for Web (49 kilobytes)

PICT format (339 kilobytes)






Figure 2.  July Heat Index Change -- 21st Century Both models project substantial increases in the July heat index (which combines heat and humidity) over the 21st Century. These maps show the projected increase in average daily July heat index relative to the present. The largest increases are in the southeastern states, where the Canadian model projects increases of more than 25F. For example, a July day in Atlanta that now reaches a heat index of 105F would reach a heat index of 115F in the Hadley model, and 130F in the Canadian model. Map by B. Felzer, UCAR, based on data from Canadian and Hadley modeling centers. Medium JPEG (109 kilobytes)

Medium JPEG Optimized for Web (52 kilobytes)

PICT format (310 kilobytes)




Figure 2.  July Heat Index Change -- 21st Century: Canadian Model Same as above. Same as above.



Figure 2.  July Heat Index Change -- 21st Century: Hadley Model Same as above.

Same as above.



Figure 3. Heat Related Deaths -- Chicago, July 1995 This graph tracks maximum temperature (Tmax), heat index (HI), and heat-related deaths in Chicago each day from July 11 to 23, 1995. The gray line shows maximum daily temperature, the blue line shows the heat index, and the bars indicate number of deaths for the day. NOAA/NCDC Medium JPEG (60 kilobytes)

Medium JPEG Optimized for Web (33 kilobytes)

Large JPEG (161 kilobytes)

PICT format (175 kilobytes)

Figure 4. Average Summer Mortality Rates Attributed to Hot Weather Episodes Deaths due to summer heat are projected to increase in US cities, according to a study using time-dependent results ( for greenhouse gas increase only) from several climate models (Kalkstein and Greene, 1997). Mortality rates (number of deaths per 100,000 population) are shown from the Max Planck Institute model, the results from which lie roughly in the middle of the models examined (the other climate scenarios used were from Geophysical Fluid Dynamics Laboratory (GFDL) and the Hadley Centre). Because heat-related illness and death appear to be related to temperatures much hotter than those to which the population is accustomed, cities that experience extreme heat only infrequently appear to be at greatest risk. For example, Philadelphia, New York, Chicago, and St. Louis have experienced heat waves that resulted in a large number of heat-related deaths, while heat related deaths in Atlanta and Los Angeles are much lower. In this study, statistical relationships between heat waves and increased death rates are constructed for each city based on historical experience. Deaths under a citys future climate are then projected by applying that citys projected incidence of extreme heat waves to the statistical relationship that was estimated for the city whose present climate is most similar to the projected climate for the city in question. This approach attempts to represent how people will acclimate to the new average climate that they experience. Note: Estimates for 2020 and 2050 are based on the Max Planck GCM results (IPCC 1994)   Medium JPEG (32 kilobytes)

Medium JPEG Optimized for Web (29 kilobytes)

PICT format (111 kilobytes)


Figure 5. Maximum Daily Ozone Concentrations and Maximum Daily Temperatures --  Atlanta and New York These graphs illustrate the observed association between ground-level ozone concentrations and temperature in Atlanta and New York City (May to October 1988-1990). The projected higher temperatures across the US in the 21st century are likely to increase the occurrence of high ozone concentrations, especially because extremely hot days frequently have stagnant air circulation patterns, although this will also depend on emissions of ozone precursors and meteorological factors. Ground-level ozone can exacerbate respiratory diseases and cause short-term reductions in lung function. Maximum Daily Ozone Chart provided by USEPA Medium JPEG (89 kilobytes)

Medium JPEG Optimized for Web (76 kilobytes)

PICT format (280  kilobytes)


Figure 6.  Seasonality of Shellfish Poisoning in Florida 1981-1994 Figure 6: Monthly distribution of oyster-associated Vibrio vulnificus illness (or shellfish poisoning) and deaths occurring in Florida from 1981-1994. Over the 14-year period, higher numbers of cases occur during summer. Monitoring in Florida shows a statistically significant association between concentrations of this pathogen in estuaries and temperature and salinity, the latter being affected by rainfall and runoff. Adapted from: Lipp and Rose, 1997. Medium JPEG (57 kilobytes)

Medium JPEG Optimized for Web (31 kilobytes)

PICT format (197  kilobytes)


Figure 7.  Combined Wastewater Systems Wastewater systems that combine storm drainage and sewage and industrial waste are still used in about 950 communities, mostly in the Northeast and Great Lakes regions. During rainstorms or spring snowmelt, when the volume of water being discharged can exceed the capacity of the sewage treatment system, these systems are designed to overflow and discharge untreated sewage into surface waters. In 1994, EPA developed a framework to control such combined-sewer overflows under the federal Clean Water Act's water discharge permit program. If combined sewer systems remain in place and continue to discharge untreated wastewater during storms, they will very likely pose an increased health risk under projected increases in intense precipitation events. Source: USEPA

Medium JPEG (68 kilobytes)

Medium JPEG Optimized for Web (36 kilobytes)

PICT format (339  kilobytes)






Figure 8.  Reported Cases of Dengue 1980-1999 Figure 8: Dengue along the US-Mexico border. Dengue, a mosquito-borne viral disease, was once common in Texas (where there were an estimated 500,000 cases in 1922), and the mosquito that transmits it remains abundant. The striking contrast in the incidence of dengue in Texas versus three Mexican states that border Texas (64 cases vs. 62,514) in the period from 1980-1999 provides a graphic illustration of the importance of factors other than temperature, such as use of air conditioning and window screens, in the transmission of vector-borne diseases. National Institute of Health, Mexico; Texas Department of Health; US Public Health Service. Unpublished data. Medium JPEG (57 kilobytes)

Medium JPEG Optimized for Web (29 kilobytes)

PICT format (236  kilobytes)






USGCRP logo & link to homeUS Climate Change Science Program / US Global Change Research Program, Suite 250, 1717 Pennsylvania Ave, NW, Washington, DC 20006. Tel: +1 202 223 6262. Fax: +1 202 223 3065. Email: Web: Webmaster: