There have been many widely publicized factors behind the spread of the COVID-19 pandemic: the use of live animal markets, government policy to contain the spread once the virus arrived, global air travel, to name a few. However, one key factor that may also have contributed to the emergence of the virus has been somewhat overlooked – deforestation and the destruction of natural ecosystems.
Deforestation is fueling modern challenges such as global warming, climate change and extinction. Deforestation can contribute to the start of global pandemics, too. Unfortunately, the COVID-19 pandemic has added momentum to the problem of deforestation around the globe. It’s a vicious cycle that’s spinning out of control.
“Ebola is a classic example where recent deforestation could have predicted the Ebola outbreak,” said Christina Faust, a postdoc at the Center for Infectious Disease Dynamics at Penn State University. “There are several pathogens that once you have a deforestation event, then you get spillover. And we don’t know whether that’s because we’re losing biodiversity that otherwise would help dilute that pathogen or if that’s humans coming into the area and increasing their risky behaviors.”
In 2018 alone, 30 million acres of tropical rainforest were destroyed, with more than a third of the Earth’s land now being used for agriculture, a process that involves the clearing of woodland to create pasture. Tropical forests have suffered the most damage, especially over the last three decades. Southeast Asia has deforested more land than anywhere in the world over the past 40 years. The Amazon basin has endured a similar loss. These areas have more endangered species than anywhere else in the world. They also have many endangered cultures that depend on their tropical rainforests. Human settlements are increasingly coming into contact with animals that had previously been naturally contained in woodland habitats.
Reduced monitoring by enforcement authorities and social upheaval contributed to the increase.
Edward Barbier, a professor at Colorado State University, is studying the relationship between economics and ecology. He says the pandemic is forcing more people to lean on the land for money and sustenance. Meanwhile, government resources are being consumed by the pandemic, leaving forested areas unprotected and vulnerable to exploitation.
A new study, by the School of Earth, Energy & Environmental Sciences at Stanford University has suggested that deforestation could lead to a rise in the occurrence of diseases like COVID-19. Its findings suggest that when forests are cleared for agricultural use, the chances for transmission of zoonotic diseases increase. Viruses that jump from animals to people, like the one responsible for COVID-19, will likely become more common as people continue to transform natural habitats into agricultural land. The analysis reveals how the loss of tropical forests in Uganda puts people at greater risk of physical interactions with wild primates and the viruses they carry.
In Africa, this has accounted for about three-quarters of recent forest loss. What remains, outside protected parks and preserves, are small islands of forest in a sea of farmland and areas where farmland intrudes into larger forested areas.
In Uganda, decades of migration and the creation of farmlands outside Kibale National Park have led to a high density of people trying to support their families at the edge of forested habitats. Ordinarily, people avoid wild primates because they are well-known carriers of disease. However, continued deforestation means wild primates and humans are increasingly sharing the same spaces and competing for food.
“At a time when COVID-19 is causing an unprecedented level of economic, social, and health devastation, it is essential that we think critically about how human behaviors increase our interactions with disease-infected animals,” says lead author Laura Bloomfield, an MD student in the School of Medicine and a PhD candidate in the Emmett Interdisciplinary Program in Environment and Resources within the School of Earth, Energy & Environmental Sciences at Stanford University.
When people venture into forested areas for resources and when animals venture out of their habitats to raid crops, the chances increase for transmission of zoonotic—or animal-to-human—disease. Another prime example is HIV, which is caused by a virus that jumped from wild primates to humans via infected bodily fluids. The Zika virus spread across the world after finding a host mosquito that thrived in urban areas.
Unfortunately, greedy corporations have taken advantage of the COVID pandemic to seize land and natural resources for exploitation. Meanwhile, those living in poverty have been driven into the forests to survive by any means possible, including poaching, logging and illegal mining.
Despite the government-imposed lockdowns and worldwide economic shock as a result of the pandemic, there is still both the capacity to illegally harvest products from tropical forests and sufficient demand for those illegal products.
“I’m hopeful that one of the most positive things to come out of horrible tragedy will be the realization that there is a link between how we treat the forest and our wellbeing, said Tierra Smiley Evans, an epidemiologist at the University of California. “It really impacts our health. It is not just a wildlife issue or an environmental issue.”
As natural habitats for wild animals shrink due to human activity, various creatures are forced to interact more with each other, making it more likely that a virus will mutate between different species.
“The problem is when you put different species that aren’t naturally close to one another in the same environment, that allows virus mutations to jump to other species,” said Alessandra Nava from the Biobank research center.
To make matters worse, wild animals may also be forced to migrate into areas more heavily inhabited by humans.
“As natural habitat is diminished, wildlife come into closer contact with people,”said Dr. Christine Johnson of the University of California, Davis.
The CDC reports that 3 out of 4 new or emerging infectious diseases come from animals, and 6 out of 10 known infectious diseases in humans can come from animals.
COVID-19 originated in bats, according to the World Health Organization, but it is unclear how or through which animals the disease was transmitted to humans. Roger Frutos, a specialist in infectious diseases at the University of Montpellier, co-authored a study in 2018 warning of the risk of a novel coronavirus emerging from bats — linking the likelihood to environmental changes.
“When you cut down trees and remove the forest, you eliminate the natural environment of some species,” he said. “But those species don’t just disappear. We instead create a patchwork, a mosaic of their environment that’s closer to ours, with houses that attract insects or sheds where bats can rest and find shelter.”
The equivalent of 27 soccer fields’ worth of forest is being lost every minute, according to the World Wildlife Fund (WWF), and deforestation has been getting worse over the past five years. It is a significant problem in the Amazon rainforest — a major source of biodiversity — where 17 percent of the forest has been lost in the past 50 years, according to the WWF, and deforestation in Brazil continues to increase.
Although we are too early into the coronavirus pandemic to say exactly how the virus started, bats are ‘reservoirs’ of viruses, possessing strong immune systems that let them harbor multiple coronaviruses without displaying symptoms. Some estimates suggest that bats may carry as many as 3,000 coronaviruses.
“At the end of the day, land conservation and the reduction of forest fragmentation is our best bet to reduce human-wild animal interactions,” says coauthor Tyler McIntosh, a former graduate student in the Stanford Earth Systems Program now working at the Center for Western Priorities.
Deforestation, human population growth, and inter-species animal contact – is a grave health risk for human society. Even before COVID-19 wreaked havoc with the global economy and national health systems, scientists were warning of the risks posed by deforestation. A group of European scientists cautioned in 2018 that, “the probability of occurrence of the risk of a pandemic is increasing owing to environmental change and higher environmental pressure.”
Meanwhile, we can’t let pandemics allow us to let down our guard on biodiversity and endangered species. Strict lockdowns have caused a sharp drop in Africa’s tourism revenue, which helps to sustain wildlife reserves and community conservancies across the continent. Without money to support rangers’ salaries and airplane patrols, elephants and rhinos are vulnerable to poachers.
“In Africa, there has been an alarming increase in bushmeat harvesting and wildlife trafficking due to COVID-19-related lockdowns, decreased food availability and damaged economies as a result of tourism collapses,” said Matt Lewis, who leads Conservation International’s work on wildlife trafficking issues in Africa.
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