Effects of Climate Change on Human Health
The National Institutes of Health, the Environmental Protection Agency, and the National Oceanic and Atmospheric Administration recently released a report on the human health effects of climate change. Whether you believe that the rise in global carbon dioxide levels and world-wide temperatures (which are indisputable) have been caused or contributed to by human activities, the report outlines how those changes have and will affect human health in the US and elsewhere.
Human health has always been influenced by climate and weather, especially by weather extremes. We have already seen more extreme weather events in recent years such as more drought, heat waves, wildfires, floods, stronger storms, and increased hurricane activity. In addition to these more obvious threats to health, our changing climate affects the behavior of mosquitos, ticks, rodents, and other species that carry diseases such as Zika and West Nile viruses and Lyme disease. Increased global temperatures will also tend to adversely affect air quality. Increased average temperatures can also threaten water quality and food safety.
As with most threats to human health, the severity of the outcome will depend on how much exposure to the stressor a person has and how sensitive or vulnerable the person is to the threat. The very young, the very old, pregnant women, and people with pre-existing disease are especially at risk. People in the lower socio-economic classes, both here and abroad, will have fewer resources to adapt to or to recover from health threats.
People with asthma (about 8 percent of the US population) are more sensitive to increased amounts and longer seasons of pollen in the air. Individuals suffering from chronic obstructive pulmonary disease (about 6 percent of US adults) are more affected by worsening ambient air quality. Diabetics (about 9 percent of the US population), people with cardiovascular disease, and people who are obese (about 32 percent of US adults) are more vulnerable to heat stress.
As with all scientific inquiry, there are uncertainties associated with assessing the human health risks of climate change. First among these are uncertainties in the future concentrations of greenhouse gases and how these will affect the warming of the earth. There are also uncertainties in predicting the future health impacts of temperature increases. It would be ideal to have complete socioeconomic, geographic, demographic, and health data for all, but those data are not generally available for practical and confidentiality reasons.
We currently have a fairly good understanding about how air quality and ambient temperatures directly affect health. Many indirect stressors such as pollen incidence and distribution, the amount and extent of infectious disease pathogens and vectors and how they affect health, however, are much less well-understood. Characterizing the “exposure-response” relationship for these indirect effects is a challenge we currently face.
For more details on this topic, see the full report which is available at https://health2016.globalchange.gov/.