Pandemics and endemics have emerged and reemerged throughout the centuries, with humans finding ways to survive and adapt. COVID-19 has swept through nations worldwide in recent years, causing high mortality rates and health and socioeconomic distress.
However, as scientists scramble to understand the origins of the coronavirus and how new strains form over time, the question remains whether climate change will increase the likelihood of future pandemics and the spread of pathogens.
The emergence of new diseases
Climate change has become a contentious and politicized topic worldwide. A portion of the population believes the world faces little impact from climate change, while others remain adamant the risks are a grave concern.
According to a Pew Research Center study that surveyed people from 14 countries, 7 in 10 people believe climate change is the biggest threat we’re facing. Another 69% of those surveyed felt infectious diseases are the biggest threat. But do climate change and infectious diseases go hand in hand?
Climate change creates the right conditions for a virus’s development and survival and influences the way it circulates. When weather events and rising temperatures alter ecosystems, the health effects are significant.
For example, the African Rift Valley fever (RVF) is closely associated with increased rainfall and has led to explosive transmission rates from animals to humans. Meanwhile, warmer weather drives higher cases of bluetongue, hantavirus, and Lyme disease.
This emergence of climate-related disease will put epicenters at risk of economic and environmental despair. The wide range of vector-borne pathogens carries dire consequences for clean water and food accessibility, leading to 700,000 deaths from parasites, bacteria, or viruses each year.
The impact of climate on transmission
When we consider zoological diseases, it’s apparent that climate has played a role in rapid transmission and spillover. A spillover event occurs when a virus can overcome specific barriers to spread more easily from species to species.
For example, mosquitoes use temperature-sensing receptors on their antennae to detect heat and latch onto their prey. As the planet warms, dangerous mosquito populations will migrate northwards, infecting more people.
The World Health Organization (WHO) states that the dengue epidemic affected nine countries before 1970. Today, 129 countries have local mosquito populations that carry dengue, with 4.2 million cases reported in 2019.
Climate change creates the perfect conditions for pests to populate, as well. An increase in pests can cause severe allergies and respiratory diseases. With the rapid reproduction of pests, ticks, fleas, and mosquitoes in hotter environments, more humans and animals face more significant infection risks.
Tropical regions have a much higher transmissibility and spillover risk than others due to having the largest animal diversity globally that carries vector-borne pathogens. Because food markets are common in these areas, a significant spread of disease will likely occur between animals and humans.
The future of pandemics
While scientists have yet to figure out if climate change has directly influenced the spread of the coronavirus, several factors should be considered for future pandemics.
According to the Food and Agriculture Organization of the United Nations (FAO), agricultural expansion accounted for 33-40% of tropical deforestation between 2000 and 2010. Additionally, nearly 198 million acres of the world’s forests have been lost since 1990.
The degradation of habitats has led to animal migrations, putting humans at a higher risk of contact with germs. Large livestock farms are also a source of spillover from animals to humans. By decreasing the demand for meat and promoting sustainable farming, society can lessen the emergence of infectious diseases.
A recent study also suggests people were more likely to die from COVID-19 if they lived in a poorer area with heavy air pollution. If air pollution influences higher mortality in vulnerable people with less access to health care, then more significant air pollution mitigation is required to assist these populations during future pandemics.
COVID-19: Not the first or the last
Scientists have learned a lot about the novel coronavirus over the last two years. However, as climate change impacts the emergence and spread of new diseases, the human race needs to be prepared for future pandemics. Now is the time to address climate change for the health of society.