Why our shrinking natural world is increasing the pace of global pandemics

While pandemics and major epidemics have been defining moments throughout history, compared to now, they used to be relatively rare. That’s changing this century: first came SARS, then the swine flu, MERS, a new outbreak of Ebola, Zika, Dengue fever, and now COVID-19. And while scientists race to develop a vaccine and drugs for the new coronavirus, that won’t solve the larger problem. There’s a clear link between the spread of viruses and the relationship between humans and the natural world—and if that relationship doesn’t change, we can expect to see more pandemics in the near future, some of which may be far deadlier than COVID-19.

“The difference between today and 100 years ago is that we’re dismantling the living world at a rate that’s unprecedented in human history,” says Aaron Bernstein, director of the Center for Climate, Health, and the Global Environment at the Harvard T.H. Chan School of Public Health and a pediatrician at Boston Children’s Hospital. “We’ve got climate change, which is pushing every living thing that isn’t human to the poles, more or less, to get out of the heat. We’re radically changing how we do business with the biosphere. And that creates the opportunity for viruses and bacteria to get into new species that they weren’t in before.”

In some cases, the link is very direct. The current outbreak seems to have started at a Chinese market that sold wild animals for food, including wolf pups, civets, bamboo rats, and crocodiles; pangolins, a type of anteater, may have been the vector. The animals, now endangered, have been illegal to sell there for more than a decade, but the laws haven’t been widely enforced. “It’s just insane, in today’s world, to have global trade in wildlife and wildlife parts, because that’s taking something that used to be isolated and moving it all around the world into highly populated areas,” says Lee Hannah, a scientist at the nonprofit Conservation International. “Coronavirus is nothing compared to what’s out there—just think about Ebola.”

Before the world was as closely connected, viral outbreaks were sometimes more limited. “When these diseases were passed to humans, sometimes, like flu, they become well entrenched and entered the human ecosystem, but other times, the really nasty ones would impact possibly a community of forest people, and it might wipe out a village,” Hannah says. “But it wouldn’t wipe out the whole planet. When we start trading wildlife all around the planet and seeing declines in the health of nature, then you face the prospect of those diseases that used to die out in an isolated, lowly populated forest somewhere spreading all around the world.”

Urbanization and globalization also mean that when a virus jumps from an animal to a human, it can now spread quickly. Wuhan, where the new coronavirus emerged, is one example of the overall trend. The city sprawled between 2000 and 2018, tripling in size, while new rail lines and flights connected it to the rest of China and the world.

China has taken new action to stem illegal wildlife trade, and shut down wildlife markets, though it remains to be seen how permanent the changes will be (after the SARS outbreak, which was also linked to wildlife markets, the markets closed only temporarily.) But eating wild animals is only one part of the problem. As humans continue to expand into previously uninhabited areas, it’s more likely that humans will come in contact with viruses that circulate in animals. There are more than a million viruses similar to new coronavirus; one organization has documented more than 500 different types of coronaviruses in bats alone. As forests are logged and oceans are overfished, pressure on animals increases, which may increase the chance that they get sick. Stress from climate change, including if it forces some animals to move, could also make it more likely that they get sick.

It’s critical, Hannah says, that nature is protected in a way that can keep ecosystems healthy. “We want to reenvision humans’ relationship with nature, and have a healthy relationship between people and nature,” he says. The recent Convention on Biological Diversity suggests aiming to preserve 30% of the planet for nature—a small fraction, but something that could easily be lost as the human population grows and agriculture expands.

Protecting nature might seem like a luxury, but it’s a vital part of public health. “We think we can handle this, and if another disease emerges, we’ll have a vaccine, we’ll protect ourselves,” says Bernstein. “I’m hoping a silver lining of the mess that’s unfolding in front of us is that we realize that after-the-fact actions simply are not that great in protecting ourselves, and that we know why these things happen and we can do things that prevent it.”

We should be as alarmed by the statistics about the natural world as the stock market, he says. “I think it’s quite clear that the rapid rate of biodiversity loss is a measure of how much we’re disturbing the living world upon which our health depends. People get really upset when the stock market takes massive punches. Well, if people think the stock market is a measure of human welfare, magnify that by a millionfold and look at the amount of life we share the planet with. Then you have something to really be concerned about.”