The Impact of Climate Change on Health

Physicians practicing in the era of climate change must become aware of how climate change is projected to affect the health of our patients and the rest of the population.(1) Changes in infectious disease transmission due to climate change are not fully understood or agreed upon, even among experts. Determining the ways in which climate change may increase infectious disease transmission may help mitigate the direst predictions.

In addition to increasing exposure to infectious diseases, changing weather patterns associated with climate change are projected to impact human health.

First, as a direct result of global warming, rising surface temperatures, especially at the Arctic and Antarctic poles, have the potential to lead to a heightened risk of exposure to infectious diseases.(2) As temperatures rise, pathogens are more easily able to reproduce. Rising temperature also permits the northward expansion of disease-carrying vectors, potentially introducing pathogens to previously unexposed communities. Warmer winters also may allow disease-carrying arthropods to survive and reproduce at unprecedented rates.(3) Thawing permafrost has already led to an increase in infectious diseases in the Arctic. Anthrax infections are increasing in northern Russia, where cattle carcasses, previously entombed in permafrost, are contaminating soil and water. As the permafrost thaws, contaminated flood water is released into the environment. Human exposure to anthrax from these animal carcasses is due to direct contact with infected animals, spores, and insect vectors.(3)

Potential exposure to infectious diseases in association with climate change is not limited to the Arctic polar cap. Projected habitat fragmentation driven by climate change will likely lead to changes in tropical disease transmission as well.(4) The extent to which transmission of tropical diseases may increase or decrease depends on regional factors such as ecological changes, agricultural development, changes in human demographics, international travel and commerce, microbial adaptation and change, and breakdown of public health measures and deficiencies in public health infrastructure.(5) A worst-case scenario model suggests that nearly one billion people may be newly exposed to viral infections from mosquitoes within the next century.(6)

In addition to increasing exposure to infectious diseases, changing weather patterns—including increased risk of heat waves, increased risk of flooding, and increased severe weather patterns—associated with climate change are projected to impact human health.(7) These predicted climatic events have the potential to overwhelm localized healthcare facilities.(8) For example, an increased risk of drought is directly associated with many health impacts, including potential exposure to respiratory irritants, food and water insecurity, and even increased risk of mental illness.(9)

These climate changes also are likely to result in an increased risk of wildfires.(10) The projected health impacts due to increased wildfires are grim; one study estimated that exposure to fine particulate matter due to increasing wildfires resulted in a two-fold increase in premature deaths related to smoke exposure by 2016.(11)

Increased flooding of large landmasses is associated with an increased likelihood of exposure to diseases, especially in low-income countries.(12) Severe weather patterns could result in an increased loss of life from flash flooding, high winds, and storm damage. Furthermore, the impact of severe weather patterns on infrastructure could prevent communities from accessing food and water supplies as well as medical care and medical supplies.

Economic Effect of Climate Change

Because the effects of climate change are so diverse and variable, the global economic impact of climate change is difficult to quantify and predict. However, changes in weather patterns, increased levels of atmospheric carbon dioxide, increased ocean acidification, increased surface temperature, and increased rates of sea-level rise, among dozens of other climate change–related factors will have a quantifiable impact on global GDP.(13)

The effects of climate change on underserved populations should be thoroughly examined by policy makers, climate scientists, and healthcare workers.

The global economic impact of climate change is inherently complex, extensive, and diverse. The following section briefly explores current literature pertaining to the economic impact of climate change on healthcare, and the ways in which climate change–related health issues will affect the economy.

One surprising effect of climate change is its threat to the United Nations’ goal of achieving universal healthcare by 2030. Due to changes in disease range and transmission in response to the changing climate, the threat of certain noncommunicable diseases is increased.

One of the most well-studied health-related climate change impacts is the effect on human health of increased exposure to heat. Rising surface temperatures are expected to decrease the productivity of both outdoor workplaces and indoor workplaces without air conditioning. These impacts are more likely to occur in developing countries, especially because air conditioning is not as prevalent as in more developed countries.(14) The short-term effects of increased core body temperature include decreased cognitive ability and increased risk of accidents; the long-term effects include an increase in renal diseases due to long-stranding dehydration. Life-threatening impacts of acute heat exposure include heat stroke and possibly hyperpyrexia.(15) These increased occupational health risks may be less severe in developed nations where air conditioning is widely available, but the productivity of the outdoor workforce, especially in developing nations located in the tropics and subtropics, will decrease as surface temperature increases.(14)

Healthcare infrastructure may be affected by severe weather events, such as those seen with hurricanes and floods, in multiple ways. Physical obstructions that may limit healthcare access because of severe weather events include direct damage to healthcare facilities as well as damage to roads, railways, and airports. Additional impacts include damage to municipal services such as water, sewage, and electricity following a severe weather event. Loss of power or water could interrupt at-home treatment or monitoring of some patients with chronic diseases. Access to healthcare also may be disrupted by a change in service demand following severe weather events. For example, hospitals may become inundated with patients suffering from hypothermia and frostbite during an extreme cold front, especially in areas where this type of weather is not common. This would limit the resources available to patients coming to the hospital for medical emergencies unrelated to the storm. Hospitals may be forced to prioritize certain patients, limiting the availability of care to others. Rationing of healthcare has never been acceptable to governments or to the population at large.(16)

Additionally, the potential effects of climate change on underserved populations should be thoroughly investigated by policy makers, climate scientists, and healthcare workers. Where there are current vulnerabilities, climate change will only act as a catalyst to wreak havoc in susceptible communities. The Intergovernmental Panel on Climate Change stated in 2001 that developing countries will face the brunt of negative impacts associated with climate change. We are seeing the reality of the IPCC’s prediction today: for example, in 2017 Hurricane Maria killed nearly 3000 people in Puerto Rico. The intensity of this storm was directly correlated to the water temperature of the Gulf of Mexico at the time—the highest temperature in the Gulf’s recorded history.(17)

Call to Action

The Hippocratic oath, written over 2000 years ago—“I will protect the environment which sustains us, in the knowledge that the continuing health of ourselves and our societies is dependent on a healthy planet”(18)— places a level of responsibility on physicians to protect the environment. Physicians can demonstrate their concern regarding the environment by becoming environmental role models—a responsibility that includes adopting personal lifestyle changes that reduce carbon consumption, advocating for policy in favor of reducing greenhouse gases, and educating patients on the potential health consequences of climate change. By participating in just a few of these activities, physicians can make real progress toward lessening the impact of climate change on our patient population and on our planet.

However, physicians first must become knowledgeable and informed about the impact of global warming. Physicians might begin this climate change education by asking themselves what will be the physiological consequences on the human body of increased atmospheric carbon dioxide or an increase in Earth’s surface temperature. If there is a change in disease vectors, we must become aware of these changes and how they will affect our patients. If physicians participate in protecting the environment, we can proudly state that we are upholding the Hippocratic oath by disease prevention, which is “always preferable to cure.”(19)

Supporting local, national, and international regulations that limit greenhouse gas emissions is not the only way physicians may advocate for policies that mitigate climate change. For example, in our practices and in the hospital, physicians should encourage recycling (when possible), reduce paper consumption, and support any policy that reduces energy. Such interventions can be as easy as turning off computers when not in use and ensuring lights are turned off in vacant rooms.(20)

Taking steps to reduce personal carbon consumption, such as walking or biking when possible, recycling, and avoiding single-use plastics such as plastic grocery bags, is a great way for physicians to lead by example.

Physicians may consider their own diet: a main source of the potent greenhouse gas methane is gas produced by cattle.(21) There is great potential for greenhouse gas mitigation in the livestock sector.(21) Greenhouse gases trap heat in the atmosphere by absorbing and then re-emitting ultraviolet rays reflected off the Earth’s surface. The ability of different greenhouse gases to trap heat often is compared with carbon dioxide, because it is an abundant greenhouse gas linked to anthropogenic activity. Methane traps more heat than carbon dioxide but has a shorter half-life. In other words, methane can warm the atmosphere more quickly than carbon dioxide but does not last as long in the atmosphere. Reducing the amount of atmospheric methane could reduce the rate at which surface temperatures are increasing. A surprising source of methane is cow belches, flatus, and feces. From an environmental standpoint, reducing red meat consumption may decrease atmospheric methane. Reducing red meat consumption also may decrease the risk of heart disease, colorectal cancer, and type 2 diabetes.(22)

Physicians also may encourage patients to decrease red meat consumption, on both environmental and health-related grounds. Additionally, advising patients to take up activities such as walking or biking to increase their daily exercise may improve the health of both the patient and the Earth. Providing unbiased and objective information to patients about the effects of climate change is an important way that physicians can provide the most effective patient care and depoliticize the conversation about climate change.(23)

Conclusion

As physicians, we affect thousands of patients by setting an example and trying to educate our patients about their role in global warming. Fortunately, many ways exist for physicians to help fight climate change and reduce our own environmental impact or our carbon footprint. Individual actions that can have the greatest effect include things such as eating less red meat and traveling less, especially by airplane. An alternative is to take public transportation, bike, walk, or work from home. A significant opportunity exists in considering converting from fossil fuel automobiles to electric cars. Doctors can make our homes sustainable by using energy-saving appliances and low-flow showers and sinks. Invest in and support businesses that practice climate consciousness.

Credible scientific reports have shown clear evidence that our patients are facing adverse health effects associated with climate change. From heat-related injuries and forest fire air pollution to worsening seasonal allergies and storm-related illness and injuries, it is important that physicians make every effort to put environmentally friendly practices in place to lessen the harmful impact that climate change is having. We must do our part, which means serving as role models and reaching out to our patients and providing them with education and information about global warming. We also have to do our part, however small, to make a dent in the increasing heating of the atmosphere. Physicians alone may not be able to solve the problem; however, we can work with the stakeholders, such as our parent organizations, the government, and other policymakers. Physicians are in a position to help combat climate change by advocating for climate change adaptation and mitigation policies, helping to advance a low-carbon health footprint, and by educating patients and communities about potential health dangers posed by climate change.

References

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