COVID-19 is a precursor for infectious disease outbreaks on a warming planet

In his book, “The Great Influenza,” John Barry writes that the 1918 flu pandemic was the first time that “modern humanity . .  would confront nature in its fullest rage.” However, 2020 has shown us that the true extent of nature’s rage is just beginning. 

From the wildfires that destroyed millions of acres across Australia and California to a record-setting hurricane season, climate change has collided with COVID-19 to mark one of the most difficult years in modern human history. And while two highly effective vaccines have provided hope for the pandemic’s end, we must not become complacent. We must act aggressively on climate to prevent future pandemics from occurring more frequently.

Emerging infectious diseases (EIDs) have been present for thousands of years, but the past couple decades alone has been rife with outbreaks: Influenza H1N1, Ebola, Zika, Avian influenza, MERS-CoV, and SARS-CoV1. This list is an example of what Dr. Anthony Fauci and medical historian Dr. David Morens refer to as a “pandemic era,” a time in which disease outbreaks become the norm rather than the exception. Like its predecessors, COVID-19 is a zoonotic disease, one that can be transmitted between animals and humans. It is thought that 75 percent of EIDs are zoonotic in nature, and one study estimates that there are 3,200 coronaviruses in bats that could jump to humans at any time. 

The risk for zoonotic diseases to pass from animals to humans is now higher than ever. Human activity has altered the way in which we interact with nature in multiple ways, much to the detriment of our own wellbeing. Global warming has led to a dangerous loss in biodiversity, resulting in increased transmission and incidence of disease. Animals are changing their habitats as their food and water supplies are threatened by altered climate patterns and processes like urbanization and deforestation, the latter of which have left only 15 percent of the world’s forests intact. With this decrease in habitat, bats and rodents such as rats, which are responsible for 60 percent of the diseases that are transmissible to humans, have flourished over declining large mammal populations.  

In addition, animal species and humans are increasingly interfacing with one another, heightening the chance for exposure to EIDs. High levels of “land use change” for  farming and livestock breeding, or road building and mining, have led to outbreaks like the Nipah virus in Malaysia. A 25 percent loss in forest cover is associated with disease spillover from animals such as fruit bats, one of the most common reservoirs of zoonotic diseases. Even more direct is the interaction that occurs in wildlife markets and the legal and illegal trade of wildlife, the former of which is thought to have contributed to the COVID-19 outbreak.       

As these animals find a foothold, altered weather from climate change also contributes to the spread of EIDs like vector-borne diseases. These diseases rely on insects like mosquitoes or ticks for transmission into human blood and account for one-third of EIDs. With warming temperatures and changes in precipitation, these insects are now being found in unexpected places. It is estimated that by 2050, mosquitoes that carry vector-borne diseases will reach 500 million more people, including 55 million Americans. The West Nile virus outbreak in New York and, more recently, the growing number of Lyme disease cases in previously unseen regions, are just a glimpse of what we may face in the future.   

As we battle the COVID-19 pandemic, the need to address underlying environmental drivers is more urgent than ever.  President Biden’s ambitious climate agenda to achieve net zero emissions from the U.S. economy by 2050 is just one part of a multi-pronged approach. The new administration must also be willing to fund research programs like the Pandemic Influenza and other Emerging Threats (PREDICT), a surveillance program whose funding was abruptly cut by the Trump administration three months before the start of COVID-19. 

In addition, the U.S. must join with other nations in collective climate action. One study suggested that the cost of preventing another pandemic through actions such as  removing deforestation subsidies, supporting the rights of indigenous peoples and monitoring wildlife trade would be just 2 percent of the current cost of COVID-19. 

If there is one lesson that we can take away from the past year, it is this: our actions have driven nature to its brink. Unless we recognize the relationship between climate and health, and the absolute necessity for real environmental policy, we will continue to suffer the consequences of our own inaction.

Dr. Christine James is an allergist-immunologist and a member of Climate Health Now, a California-based health care professional organization that recognizes climate change as a public health emergency, and the Public Health Advisory Committee of Climate Action Campaign. Follow her on Twitter: @ChristineRJames.

Dr. Sweta Chakraborty is behavioral scientist, oped and book author and regular broadcast news commentator (CNN, FOX, BBC, etc.). She is also on EcoHealth Alliance’s Leadership Council. Follow her on Twitter: @swetac.