Climate Change and Human Health
Climate change is happening now, and we are already experiencing its consequences. Contrary to common belief, it is not only an environmental concern – implications affect humans, from heat stroke and disease to famine and political instability.
- The primary cause of global warming and climate change is the combustion of fossil fuels, mainly coal and petroleum. The incomplete burning of these fuels releases pollutants into the air, including microscopic particles known as black soot. Black soot is a known carcinogen, and it aggravates existing ailments such as emphysema, chronic obstructive pulmonary disease, asthma, and can even cause death. The EPA estimates that asthma kills more than 5,000 Americans a year, a mortality rate three times greater than just 20 years ago.
- On clear days, nitrogen oxide gas and volatile organic compounds (mainly from automobile exhaust and coal fired power plants) chemically react with sunlight to form ground-level ozone. Ozone irritates the lungs when inhaled, aggravates asthma, raises the risk of pneumonia, and can lead to permanent lung damage.
- Increasing global temperature has been linked to the rise in frequency of heat waves and other severe weather events. Heat waves can lead to dehydration, heat stroke and even death. Young children, the elderly and those with medical conditions are most susceptible to elevated temperatures. Lower-income populations are also at risk, as they have limited resources to respond to the heat. Over the summer of 2012, there were 82 reported heat-related deaths in the US and Canada. The unusual heat was also blamed for the June 2012 derecho in the Northeast, which killed 23 people and left 4.2 million without power. The extreme summer heat wave across Europe in 2003 caused over 70,000 deaths in twelve countries.
- Climate change has numerous indirect effects on human health, especially via extreme weather. An increase in the severity of hurricanes, flooding, tornadoes, rain/snow storms, heat and drought have been linked to climate change. Severe weather can lead to a scarcity of food and water, the interruption of utility and health services, the spread of disease in crowded recovery areas, psychological trauma associated with the catastrophes, and other conditions that indirectly impact human health.
- Over the past year the United States has experienced an unprecedented number of extreme weather events. Superstorm Sandy claimed over 180 lives (88 in the United States) and brought the New York metropolitan area to a standstill. In July 2012, the hottest month ever recorded in US history, the USDA declared more than half of all US counties disaster areas, mainly due to drought. Visit our extreme weather page for more information.
- Heat waves increase energy demand, as more people are likely to use air conditioners. This increase in energy demand in turn increases the combustion of fossil fuels, which releases more pollutants into the atmosphere. The result is a local drop in air quality, making more people sick, and the release of more greenhouse gases, which reinforces the feedback loop on the global scale.
- A less severe effect of climate change that has been observed throughout the United States is the increase in plant pollen and other airborne allergens. The spring pollen season is occurring earlier and lasting longer in some areas, leading to more discomfort for those suffering from hay fever, asthma, and other respiratory conditions. In 2012 an unusually mild winter resulted in a longer and more intense allergy season than normal, causing discomfort for millions of people.
- Long-term climate change is altering and expanding the geographic range of numerous insect species, many of which are vectors for plant, animal and human diseases. Lyme Disease, for example, is moving north into areas previously too cold to host the ticks that spread it. Also, 2012 was an exceptionally severe year for the West Nile Virus. Although the causes for the West Nile Virus outbreak are uncertain, it is known that the mosquitoes that spread the virus thrive in warmer temperatures (links to studies here and here.) It has been suggested that the unusually mild 2011/2012 winter resulted in larger springtime mosquito populations, because of the scarcity of frosts that usually thin the insect populations. Health officials are concerned that a warmer climate will result in an increase in human diseases that were previously rare or unknown in the United States.
Overall, the effects of climate change on human health are complex and far reaching. They differ from region to region depending on geographic, socioeconomic, and other variables. Drought in the Midwest over the summer of 2012 severely damaged agricultural output, raising food prices for people around the world. Drought abroad, in East Africa for example, may have more extreme consequences for already resource-limited populations and unstable governments. Drought may lead to famine, mass migration and political instability – conditions that may be taken advantage of by terrorist networks. It is for these reasons that we find ourselves in the odd situation where the US Department of Defense is more concerned about climate change than is the US Congress.
The World Health Organization estimates annual costs to health to be US$ 2-4 billion a year by 2030, and health issues are projected to worsen. In 2008, urban outdoor air pollution accounted for 1.3 million premature deaths in urban areas around the world. Over half of the world’s population now lives in cities, and the number is expected to rise to 70% by 2050.
Human Health Resources:
Climate and Health Program, by the Center for Disease Control and Prevention
Human Health Impacts & Adaptation, website by the US Environmental Protection Agency.
Books, Articles, Scholarly Publications, etc.
“Changing Planet, Changing Health” by Paul R. Epstein, MD and Dan Ferber. University of California Press. 2011.
What’s Causing the West Nile Virus Outbreak? Butler, Kiera. Mother Jones. 2012.
Impacts of climate change on aeroallergens: past and future. Beggs, P.J. Clinical & Experimental Allergy. 2004
Recent warming by latitude associated with increased length of ragweed pollen season in central North America. Ziska, Lewis et al. Proceedings of the National Academy of Sciences of the United States of America. 2011.
Production of allergenic pollen by ragweed is increased in CO2-enriched atmospheres. Wayne, Peter et al. Annals of Allergy, Asthma & Immunology. 2001.
Biomass and toxicity responses of poison ovy to elevated atmospheric CO2. Mohan, Jacqueline E. et al. Proceedings of the National Academy of Sciences of the United States of America. 2006.
Global Climate Change and emerging infectious diseases. Patz, J.A. et al. JAMA: The Journal of the American Medical Association. 1996.
Diesel Engine Exhaust Carcinogenic. World Health Organisation. 2012.