Commentary
Climate Change and Health Vulnerabilities
Because climate change will directly and indirectly affect human health in adverse ways, physicians should be advocating strongly for policy changes that will stem global warming.
By J. Drake Hamilton, M.A.
Scientists have acknowledged that global warming, or climate change, is a reality caused primarily by human activity, in particular, the burning of fossil fuels such as coal, oil, and natural gas, and the clearing of forests. It is now accepted that burning fossil fuels releases into the atmosphere carbon dioxide, which traps heat and increases surface temperatures. As we have become more dependent on cars, coal, and oil to power our lives, the evidence that the planet is warming has mounted: NASA’s Goddard Institute for Space Studies recently reported that the 10 warmest years on record (since 1880) have occurred between 1997 and 2008.1
Environmental scientists warn that the world as we know it is changing. In Minnesota, if our heat-trapping emissions continue to increase at current rates, it is projected that summers routinely will be as hot as they were in 1988, the state’s hottest summer on record.2 According to research by the Union of Concerned Scientists, average summer temperatures in the state will increase by 12 degrees F by the end of this century. If that happens, the Minneapolis-St. Paul metropolitan area would experience almost 70 days each summer with high temperatures over 90 degrees F and almost 30 days with temperatures higher than 100 degrees.3 In addition, the Twin Cities would face at least two heat waves per summer on par with the one that killed hundreds of people in Chicago in 1995 and at least one as deadly or deadlier than that which killed tens of thousands of people in Europe in 2003.3,4 The warming of the earth has health consequences for the population. Some of those already have been documented; others will be felt in our lifetimes and those of our children.
The Intergovernmental Panel on Climate Change (IPCC), the international scientific body established by the World Health Organization and the United Nations Environment Programme to provide a scientific view on the current state of climate change and its potential consequences, has issued a series of reports on global warming. Its most recent climate assessment (2007) incorporates a chapter covering human health.5 The IPCC found that climate change already has altered the distribution of certain infectious disease vectors, including ticks and mosquitoes in the Northern Hemisphere, and increased the number of heat-wave–related deaths. The IPCC projects with 90 percent confidence that extreme heat events will intensify in magnitude and duration in portions of the United States. If those projections are accurate, not only will there be more heat-related deaths and a greater incidence of vector-borne illness but also an increase in cardiorespiratory morbidity and mortality associated with higher levels of ground-level ozone.
In May 2009, the Lancet and the University College London Institute for Global Health released the final report of their year-long commissioned study of the health impacts of global warming.6 It represents one of the most definitive statements to date about the current and future effects of global warming on health. The report, “Managing the Health Effects of Climate Change,” calls climate change “the biggest global health threat of the 21st century” and makes it clear that the full impact of climate change on human health “is not being grasped by the healthcare community or policymakers.” Lead author Anthony Costello, MBBC, a pediatrician and director of the Institute for Global Health at University College London, said at the report’s public release that “we must develop win-win situations whereby we mitigate and adapt to climate change and at the same time significantly improve human health and well-being. There are major health benefits from low-carbon lifestyles, which can reduce obesity, heart and lung disease, diabetes, and stress.”6 A Lancet editorial recommended action steps stemming from the report’s findings and warned that “health professionals have barely begun to engage with an issue that should be a major focal point for their research, preparedness planning, and advocacy.”7
The Health Effects
To start, medical and public health professionals need to become familiar with the direct and indirect consequences of unmitigated climate change on health.
〉Direct Effects
The most obvious result of climate change is an increase in the number and severity of heat waves. We have already seen this. In the summer of 2003, when a heat wave affected Europe, as many as 35,000 people in Britain, France, Italy, the Netherlands, Portugal, and Spain died as a result of heat-related illness.8 In the United States, extreme heat events are responsible for more deaths annually than hurricanes, lightning, tornadoes, floods, and earthquakes combined.9
People without access to air conditioning are especially vulnerable to heat waves, as are people who live in city centers because of the heat-island effect. City environments, full of dark surfaces such as rooftops, streets, and parking lots, absorb heat and typically are 2 degrees to 10 degrees F warmer than surrounding areas. The urban heat island also raises nighttime temperatures, so cities don’t cool off as much as rural areas at night, and higher nighttime minimum temperatures have been linked epidemiologically with excess mortality.10
The urban poor are particularly vulnerable to the health effects of heat waves because of the heat island effect. In addition, the young, the elderly, and people with certain medical conditions including cardiovascular disease, diabetes, respiratory illnesses, and obesity are thought to be especially vulnerable to heat.11,12 Heat also has an effect on people’s mental health and well-being. Just a 1-degree F increase in temperature appears to increase the risk of violent behavior, especially in the inner city.13 Additionally, heat waves have been shown to contribute to alcohol and substance abuse.14
〉Indirect Effects
Climate change will affect health in other, less-direct ways, as well. Extreme weather events, especially heavy rains, can create conditions favorable to vector- and waterborne diseases. For example, with warmer, wetter weather, mosquitoes will move northward, carrying with them diseases such as malaria and dengue fever. Incidence of Lyme disease also will be seen further north as weather conditions shift the distribution of vector ticks. More intense storms may lead to more flooding, which is likely to result in an increased incidence of waterborne diseases such as those caused by Cryptosporidium and Giardia.11
Warming temperatures will lead to worse air quality, thus increasing the incidence of respiratory illness. Researchers have found a positive correlation between temperatures higher than 90 degrees F and ground-level ozone production. Long-term, low-level exposure to ozone has been associated with increased risk of death from respiratory causes.15 With climate change, ground-level ozone concentrations in the United States may increase by between 5 percent and 10 percent during the next 50 years.16 If Minnesota experiences 90-degree temperatures throughout the summer, as the Union of Concerned Scientists’ research suggests, the state can expect to see many more days with unhealthy ozone levels.3
Global warming is also likely to result in more fine-particulate pollution, which, according to the American Lung Association, is associated with increases in the severity of asthma attacks, the number of heart attacks, and the number of hospitalizations related to cardiovascular disease and asthma. It’s also a cause of early deaths from heart and lung disease.17 The leading source of this contaminant is coal-fired power plants, which will emit more pollution as we demand more electricity to cool homes and buildings during times of extreme heat. Thus, as Minnesotans try to adapt to global warming by relying more on air conditioning, they will unwittingly create more particulate air pollution and cause more health problems.
Action Needed
In order to prevent health problems associated with global warming, we as a nation need to take swift action to reduce the heat-trapping emissions that are the primary cause of climate change. We need to transform the world’s energy economy, moving it away from one that depends on fossil fuels and toward one that relies on low-carbon energy sources. In order to do that, the United States needs to enact a comprehensive set of climate and energy policies including new standards for renewable energy, energy efficiency, and transportation that set a tight limit on heat-trapping emissions. The goal should be to reduce emissions by at least 20 percent below current levels by 2020 and by at least 80 percent by 2050. Any delay in emissions reductions will make it more difficult and costly to adapt to the consequences of global warming.
In addition to putting strict limits on greenhouse gas emissions, the United States needs to:
- Increase energy efficiency and conservation in industrial, residential, and commercial buildings;
- Boost the use of renewable energy resources such as wind power, advanced biofuels, and solar and geothermal energy;
- Improve vehicle fuel efficiency and make alternatives to driving such as riding mass transit, biking, and walking more available and attractive; and
- Encourage reforestation and reduce tropical deforestation.
Health care professionals need to become advocates for these changes and encourage their elected representatives to take swift action. At the federal level, they should urge their lawmakers to support the American Clean Energy and Security Act of 2009, which has been passed in the U.S. House of Representatives and introduced in the Senate as the Clean Energy Jobs and American Power Act of 2009. Closer to home, health care providers can encourage their employers, hospitals, and patients to prepare for the health impacts of climate change that we are not able to avert by identifying vulnerable populations and giving their care priority during heat waves, and developing local preparedness, communication, and response plans for days when the temperature is extremely hot and the air quality poor. They should view this work as a component of practicing preventive medicine.
Unless we alter the way we live and work, we could see dramatic changes to our climate. Those working to improve the health of individuals ought to be concerned enough about the health consequences associated with climate change to work toward policy changes that will improve the health of the entire population now and in the future. MM
J. Drake Hamilton is a climatologist who directs the global warming solutions program at the Minnesota-based nonprofit Fresh Energy. Prior to joining Fresh Energy in 1995, Hamilton was an assistant professor at The George Washington University in Washington, D.C.
References
1. Goddard Institute for Space Studies. GISS Surface Temperature Analysis. Available at: http://data.giss.nasa.gov/gistemp/2008/. Accessed October 8, 2009.
2. Minnesota Department of Natural Resources, Division of Waters. Drought of 1988. January 1989, St. Paul, MN.
3. Union of Concerned Scientists. Confronting Climate Change in the Midwest (2009). Available at: www.ucsusa.org/mwclimate. Accessed October 9, 2009.
4. Robine JM, Cheung SL, Le Roy S, Van Oyen, H, Griffiths C, Michel JP, Herrmann F. Death toll exceeded 70,000 in Europe during summer of 2003. C R Biol. 2008;331(2):171-8.
5. Intergovernmental Panel on Climate Change Working Group II. Climate Change 2007: Assessment Reports: Impacts, Adaptation, and Vulnerability (Chapter 8). Available at: www.ipcc.ch. Accessed September 28, 2009.
6. Costello A, Abbas M, Allen A, et al. Managing the health effects of climate change: Lancet and University College London Institute for Global Health Commission. Lancet. 2009;373(9676):1693-733. Available at: www.ucl.ac.uk/news/news-articles/0905/09051501/. Accessed September 28, 2009.
7. A Commission on climate change. Lancet. 2009; 373(9676):1659.
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10. U.S. Environmental Protection Agency. Heat island effect. 2005. Available at: www.epa.gov/heatisland/index.html. Accessed October 9, 2009.
11. Karl T R, Melillo JM, Peterson TC, eds. Global Climate Change Impacts in the United States. Cambridge: Cambridge University Press, 2009. Available at: www.globalchange.gov/usimpacts. Accessed October 9, 2009.
12. U.S. Environmental Protection Agency. Excessive Heat Events Guidebook; 2006. Available at: www.epa.gov/heatisland/about/heatguidebook.html. Accessed October 9, 2009.
13. Rotton J, Cohen EG. “Global warming and U.S. crime rates: an application of routine activity theory.” Envir Beh. 2003;35(6):802-25.
14. Bulbena A, Sperry L, Cunillera J. Psychiatric effects of heat waves. Psychiatr Serv 2006:57(1):1519.
15. Jerrett M, Burnett RT, Pope CA 3rd, et al. Long-term ozone exposure and mortality. N Engl J Med. 2009;360(11):1085-95.
16. Kenny P. Climate change, air quality, and human health. Am J Prev Med. 2008;35(5):459-67.
17. American Lung Association. State of the Air 2009. Available at: www.stateoftheair.org. Accessed October 15, 2009.