The COVID-19 pandemic is an incredible human tragedy. Today an estimated one million people have been infected by the virus, and over 50,000 have died. And, for the foreseeable future, those numbers will be rising sharply.

But this is not the first time a new disease erupted into the human population, causing significant harm. Consider the H1N1 influenza virus, SARS, MERS, Zika virus, Nipah virus, Hantavirus, and Ebola. Or consider the terrible toll of HIV. In fact, during the last few decades, the world has seen many “emerging” and “re-emerging” infectious diseases.

Emerging Disease Threats During the Last Thirty Years. This map comes from the National Institute of Allergy and Infectious Disease and a report written by Dr. Anthony Fauci in 2017.

Many of these emerging diseases arise from changing environmental conditions — including from deforestation, habitat and biodiversity loss, wildlife exploitation, the bushmeat and traditional medicine trade, confined animal agriculture, and antibiotic misuse.

Itseems odd that these emerging infectious diseases erupted into the world after the massive improvements in public health of the 20th century, when we saw the biggest gains in life expectancy in human history. The discovery and deployment of antibiotics, the widespread use of vaccinations, increased sanitation, better food and water security, and other medical miracles extended our lives and reduced human suffering. But it also gave us the illusion that infectious diseases were a thing of the past.

But recent decades have shown us that infectious diseases never really left, and they’re back with a vengeance.

Despite what some politicians and pundits are saying, this is not a surprise. Scientists have been ringing the alarm for decades, urging us to be better prepared. Countless reports have warned us during the last thirty years, including numerous pieces by Dr. Anthony Fauci. In the popular literature, Laurie Garrett warned us about this in her New York Times best-selling book, “The Coming Plague” in 1994. And Dr. Larry Brilliant spoke about this in his TED talk (which has over one billion views) in 2006.

They all warned us that changing environmental conditions were contributing to increasing disease threats. Numerous studies highlighted how infectious diseases could arise from deforestation, habitat and biodiversity loss, wildlife exploitation, the bushmeat and traditional medicine trade, confined animal agriculture, and antibiotic misuse.

Smart leaders knew this was coming. Scientists told them, again and again. And some wise leaders started to prepare. Sadly, others ignored the science, and some recently dismantled key programs needed to combat these threats.

So, here we are.

While the emergence (or re-emergence) of infectious diseases happens for a wide variety of reasons, many of these recent threats are zoonotic diseases. That is, diseases that come from animals when a bacteria or virus “jumps” from a wild or domesticated animal into the human population. Swine flu. Avian flu. Nipah Virus. Hantavirus. Monkeypox. And so on. And now COVID-19, which is widely thought to have emerged in China’s “wet markets” — although the precise point of origin is still being determined.

The long list of emerging zoonotic diseases shows us a pattern. Many arise from humans consuming wild animals (either as meat or as traditional medicines) from Earth’s remaining wild areas, often along the ragged edges of rainforests. Some occur when healthy ecological systems that kept diseases in check (by balancing disease reservoirs, infectious agents, and vectors) are broken, allowing infectious agents to be transmitted to human populations for the first time. Others seem to arise from dense concentrations of domesticated animals raised, often with poor controls, close to human populations. These all point to situations where healthy ecological systems (which help keep diseases in check) are breaking down, allowing diseases to “jump” into the human population and spread.

While other factors can give rise to emerging infectious disease, human activities are a driver of many. In fact, back in 2005, my colleagues and I wrote an article in Science that pointed out:

“Habitat modification, road and dam construction, irrigation, increased proximity of people and livestock, and the concentration or expansion of urban environments all modify the transmission of infectious disease and can lead to outbreaks and emergence episodes.”


“Disturbing wildlife habitat is also of particular concern, because ~75% of human diseases have links to wildlife or domestic animals.”

We knew that the loss of habitats and biodiversity, breaking down natural ecological systems, and increasing contact between dense human populations, wild animal products, and poorly-regulated animal agriculture, was a recipe for disaster.

Many more studies have reinforced these conclusions. In a recent article by John Vidall, he concludes that the continued decline of biodiversity and habitat worldwide could lead to many more incidents like COVID-19.

Ina way, emerging disease events —whether SARS, MERS, and COVID-19 — remind me of storms and fires.

Storms, fires, and disease pandemics can happen naturally, of course. They have before, and they will again. But as we alter our planet’s climate, and degrade Earth’s ecosystems, we make these events more likely.

We know that climate change is increasing the frequency and severity of many weather events. We now have stronger droughts and floods, hotter and longer heatwaves, more intense fire seasons, and so on. And if climate change continues unabated, these will only get worse.

The same relationship connects emerging diseases and the decline of ecosystems. Our reckless actions — causing habitat loss, biodiversity decline, wildlife exploitation, and poor methods of animal agriculture — are linked to the emergence of infectious disease. As a result, we are seeing, and will continue to see, increases in zoonotic disease outbreaks.

In other words, storms are to climate change as disease outbreaks are to ecosystem decline.

Severe storms and disease outbreaks are single events, while climate change and ecological decline are underlying syndromes that make them more common. A flood or drought is more likely because of climate change. Diseases like COVID-19 are are more likely under ecological decline.

Wecan’t stop every bad event from happening. Storms happen. Diseases happen. But we can make them a lot less likely by addressing the underlying syndromes of climate change and ecological decline.

That’s why we must keep our eye on the bigger, systemic patterns that underlie these tragic events.

Yes, today we must focus our collective energy, talent, capital, and wisdom to addressing the COVID-19 crisis.

But, in the coming months and years, we must also address the ecological degradation that exacerbates the threat of emerging infectious disease. If we don’t, we will see more and more of these incidents in the future.

The lesson here is that weneed to respond to disastrous weather and disease events with every tool at our disposal, but we must also address the underlying syndromes of climate change and ecological decline that make them more common to truly ensure the health and security of our society.

Disasters will happen in the future, of course. But by addressing climate change and ecological decline now, we greatly reduce the odds and severity of these events and will give our society — and our children — the best chance at a healthy and safe future.

Dr. Jonathan Foley (@GlobalEcoGuy) is a renowned climate and environmental scientist, writer, and speaker. He is also the Executive Director of Project Drawdown,the world’s leading resource for climate solutions.

These views are his own.

Originally published on