Climate change significantly impacts the emergence and spread of infectious diseases. Previous work by the American Security Project discussed how increasing temperatures around the globe create conditions that favor the spread of viruses and bacteria that cause infectious diseases. These pathogens that were previously unable to thrive in cooler/drier conditions can now survive in more regions as the earth warms. Further, as the changing climate raises sea levels, increases the frequency of natural disasters, and elevates temperatures, many are forced to leave their communities due to destruction or unbearable conditions. Increasing migration rates due to climate change favors the spread of infectious disease, as pathogens travel with human vectors to new communities. This is currently a very relevant threat, as one-third of all displaced individuals are in the 10 countries most at-risk to COVID-19. Beyond these points, climate change and infectious disease also have implications on food and water availability and as a result, threaten human and economic security.
How is food connected to infectious disease?
Higher temperatures cause foodborne viruses and bacteria to proliferate. Pathogens commonly found in agriculture and poultry products thrive under warmer air and water temperatures. As the spread of these infectious agents amongst food products is likely, the risk for human exposure increases. If contracted, these agents cause a range of symptoms, and in extreme cases, lead to death. Additionally, changing climates create a more suitable environment for diseases affecting plant species. Researchers found that recent climate trends in temperate regions of the United States, Europe, and China are compatible for fungal pathogens and viruses infecting crop species. Diseases affecting crops limit their growth and threaten agricultural output.
Climate change affects the food supply in other ways too, as changing precipitation patterns alter growing season and crop yield, and increased temperatures induces crop heat stress and impact poultry living conditions. These changes can have grave impacts on malnutrition rates, and in turn exacerbate the spread of infectious disease as compromised immune systems have a harder time fighting the illness.
Rain Patterns & Heat
As introduced above, changing precipitation patterns and temperatures affect growing seasons and yield. With too much heat, crops experience heat stress in which they will wilt, leading to permanent crop damage, or more rapid growth, which translates to less time to take in energy from the sun and thus smaller yields produced. For poultry, higher temperatures translate to slower growth, egg production and quality issues, reduced meat quality, and higher cases of mortality in transport. Further, more frequent natural disasters, like drought and flooding, affect crop growth. All of these factors contribute to food scarcity.
Climate Change affecting Malnourishment
As food scarcity increases, more individuals will become malnourished. Those suffering from malnourishment are in turn more likely to contract infectious diseases, have worse symptoms, and have diminishing responses to treatment. The World Health Organization (WHO) estimates an additional 250,000 deaths per year globally from malnourishment, infectious disease, and increasing heat by 2050.
Will water be a problem too?
Like the food situation, drought and flood conditions caused by climate change deplete water supplies and make infectious disease spread more likely. Runoff from melting snowcaps and increased flooding from storms and sea-level rise picks up debris and bacteria, contaminating the water supply. Further, under drought conditions, decreased flow through rivers and streams increases pollutant concentration in bodies of water. Both factors make the spread of infectious diseases to humans through drinking water more likely. In the United States, an estimated 7 million cases and 6,000 deaths are attributed to ingesting contaminated water each year. Globally, contaminated water has a tremendous health toll, as about 829,000 people die each year from contracting an infectious disease via water.
Beyond the disease: Implications on greater security
The increasing frequency of infectious diseases due to climate change will have tremendous economic implications for communities everywhere. Research from the U.S. National Library of Medicine estimates that costs associated with rising cases of malaria, diarrheal diseases, and malnutrition may reach anywhere from $4 billion to $12 billion by 2030. This prediction does not account for additional costs in health care infrastructure, disease surveillance and monitoring, and additional infectious diseases, all of which will raise costs tremendously. For example, the U.S. spends an additional $15.6 billion each year on foodborne disease monitoring and surveillance and prevention strategies.
There will be equally immense costs for supplying clean water. According to the World Bank, providing clean water to everyone would cost approximately $150 billion each year, posing a tremendous yet mandatory cost for communities facing clean water scarcity. High costs associated with water scarcity come up in other ways beyond just the provision of water too. Across countries in the Middle East and the Sahel, water scarcity will cause an average 6% decrease in GDP due to the associated costs of decreasing water on agricultural output, health, and income. While the costs for addressing this issue are high, the costs associated with water scarcity are predicted to be five times greater.
Infectious disease’s effects on diminishing food and water supplies also increases the likelihood of conflict. Food price spikes from fewer supplies can spark protests and violence in communities, and the exacerbation of water stress will lead to competition for water, which has the capability to transform into regional conflict.
What does this all mean?
Infectious disease spread via food and water, aggravated by climate change, gravely impacts security. The complexity of this issue is furthered in the fact that climate change lowers food and water supplies- increasing the rate of malnutrition which makes the transmission of infectious disease more likely. Climate change will not reverse itself anytime soon, so measures to combat the spread of infectious disease and maintain necessary food and water supplies are essential. However, providing enough food and clean water to the global population has been a problem long before effects from climate-related infectious diseases were considered, so a solution will not be easy. The next post in this series will consider the challenges and innovative strategies associated with this issue.