What COVID-19 can teach us about future pandemics (and why we should expect them)
Key Takeaways
Mammals harbor over 10,000 viral species that could infect humans.
A new study shows that climate and land-use change increases the potential for cross-species viral transmission and future disease outbreaks.
To protect the planet and human health, physicians can advocate for climate change mitigation policies and adopt such practices as using clean energy sources and encouraging active transportation (walking, cycling) for their patients.
In 1994, Jonathan Patz, MD, MPH, was the first to facilitate a session about climate change for the American Public Health Association.[] Met with skepticism at the time, the concepts have yielded to emerging evidence nearly 30 years later confirming the relationship between climate change and disease emergence.
As the planet changes, the likelihood of cross-species viral transmission—the event that most likely led to the COVID-19 pandemic—increases.[]
To intercept the development of future pandemics, doctors can address climate change at its root through advocacy and clean energy practices.
Climate change and zoonotic viral spillover
There is convincing evidence that the COVID-19 pandemic was caused by a zoonotic viral spillover incident, in which a virus jumped from animals to humans. It won’t be the last of its kind, however, if climate change persists, according to a 2022 report published by Nature.[]
Wild mammals carry over 10,000 viral species that could potentially infect humans. Historically, humans haven’t come into contact with most of these mammals, mitigating the risk of disease emergence.
But the effects of climate and land-use change could converge to create viral-sharing hotspots between wild animals and humans. If the rate at which Earth is warming is maintained, then by 2070, there will be new aggregations of mammal-virus species in certain places, such as higher elevations, environments with higher biodiversity, and Asian and African territories with dense human populations.
The result of humans and animals living in close quarters in new combinations will lead to a higher frequency of cross-species viral spillover. Bats, in particular, due to their unique dispersal capacity, are prime suspects for novel virus-sharing with humans.
The authors of the Nature study note that this projected outcome isn’t as far off as it seems.
"Surprisingly, we find that this ecological transition may already be underway, and holding warming under 2 °C within the century will not reduce future viral sharing."
— Carlson, et al.
“Our findings highlight an urgent need to pair viral surveillance and discovery efforts with biodiversity surveys tracking species’ range shifts, especially in tropical regions that harbor the most zoonoses and are experiencing rapid warming,” the authors added.
Natural disasters, ice melting, and disease emergence
Another potential catalyst for zoonotic viral spillover is natural disasters caused by climate change.
A Cleveland Clinic article states that extreme weather such as droughts and hurricanes can displace wild animals, bringing them into closer contact with domestic animals and humans.[]
Polar ice melting is also a potential concern. Long-dormant viruses could surface as a result of thawing ice in polar regions, potentially infecting humans.
Global warming could also bring about a rise in mosquito-borne illnesses, in addition to the emergence of zoonotic disease.
Addressing the root cause can improve health outcomes
It is clear that there is a relationship between climate change and human health outcomes, including future pandemics.
The American College of Physicians has developed a Climate Change Toolkit for physicians, with recommendations for actions you can take to address climate change.[]
Be an advocate for policy change. Use your voice to ask for climate change adaptation and mitigation policies. The widespread use of clean and renewable energy sources will not only slow climate change, but also improve air and water quality.
Promote clean energy use. Ditch fossil-fuel–generated electricity for clean energy sources. The resulting reduction in air pollution will lead to lower rates of certain respiratory and cardiovascular illnesses among patients.
Encourage use of active transportation methods. Physicians, as well as patients, can try cycling or walking, if possible, instead of using gas to drive a short distance. This can also improve cardiovascular health.
Buy locally sourced foods. Reduce carbon pollution and enhance your cardiovascular health by limiting meat intake and sourcing fruits and veggies locally.
What this means for you
It’s believed that the COVID-19 pandemic resulted from zoonotic viral spillover, possibly resulting from climate change. Future potential pandemics could therefore be linked to climate change as well. Help prevent disease emergence by advocating for climate adaptation and mitigation policies. Shifting to clean energy sources and using active transportation (eg, riding a bike) may also make a difference.