The novel coronavirus (SARS-CoV-2) shows no sign of letting up soon. As the northern hemisphere moves into colder weather, an uptick in cases is materializing. Right now, much attention is focused on finding ways to defeat the virus and return global human life and mobility to some semblance of our pre-pandemic realities. As we look forward, it is important to recall that this illness came to us via zoonotic transmission, and to recognize that dangers inherent in aspects of the human-animal interface remain—and likely are intensifying—for both human and non-human animals.

Six out of ten infectious diseases in humans are zoonotic, and the U.S. Centers for Disease Control and Prevention estimates tens of thousands of Americans become ill annually from diseases spread from animals. Among them are zoonotic influenza, Salmonellosis, West Nile virus, Plague, Emerging coronaviruses, Rabies, Brucellosis and Lyme disease. Furthermore, emerging infectious diseases are increasing.

What might not seem so apparent is that many anthropogenic factors that contribute to zoonotic disease emergence also feature into climate change issues. These include human population growth requiring more space for food production, industrialized food production itself, globalization and urbanization, and climate changes that are forcing humans and other animals to migrate and redistribute geographically. In what follows, I assess this latter factor and its resultant effects.

As Bill McKibben notes in his review of Mark Lynas’ new book, Our Final Warning, “Researchers once hoped that modest warming of two degrees might actually slightly increase food production, but ‘now these rosy expectations look dangerously naïve.’ He cites recent studies predicting that two degrees will reduce ‘global food availability’ by about 99 calories a day [and] the pain will not be equally or fairly shared…. Current warming means everyone in the Northern Hemisphere is effectively moving southward at about 12.5 miles a year. That’s half a millimeter a second, which is actually easy to see with the naked eye: ‘a slow-moving giant conveyor belt’ transporting us ‘deeper and deeper towards the sub-tropics at the same speed as the second hand on a small wristwatch.’

The climate crisis is already driving mass human migrations around the globe. Maps are readily available that show further, anticipated climate change-caused migrations, with refugees fleeing sea level rise, temperature increase and resource scarcity. The redistribution of life on earth is not limited to humans. As their previous habitats become less and less hospitable, animals, too, are searching for homes more like those to which they are adapted. For land animals, this means moving to cooler, higher elevations habitats, while marine animals are moving to colder, deeper waters. 

I can speak to climate crisis migration directly. In 2018, I relocated my multi-species family consisting of humans, horses, dogs and birds from California’s Sierra Nevada foothills to northern Illinois. This was not a joyous decision. It was, rather, one forced upon me after observing the environment around us changing. First, over decades I’d watched the wildflowers, particularly one of my favorites that blankets the foothills in gorgeous blue sweeps, the lupine, bloom earlier and earlier each year. The May blooms became April blooms, then March then February. Over those same decades the fire season, previously limited primarily to the month of August, started earlier and lasted longer, with by 2018 spotter planes and plumes of smoke a daily occurrence from June through November. The last few years, for those seven months we were on constant standby with a go-bag by the door lest we received last-minute notification to evacuate nine beings. The final sign came not from a news source but from the ecosystem itself. That last year, I saw on my own acreage plants in the landscape and birds at the feeders that I’d never seen before, moving up from the valley into the mountain foothills in search of a cooler place to survive. It was then I realized we should follow their lead. The relief I felt at having our little pod (more) safe (for now) has lessened neither my grief at the loss of a place I loved nor my anxiety for the people, creatures, and biome I left behind. Moreover, I am not unaware that my own experience and emotions over this dwindle in comparison to all those of any species who make a living off the land, any land, and are going through similar, and likely worse, uncertainties and disruptions. I was able to move and had a place to move to; others are not so fortunate.

A review article in Science, Biodiversity redistribution under climate change: Impacts on ecosystems and human well-being by Gretta Pecl and colleagues notes that in 2017 at least 25% and perhaps as much as 85% of Earth’s estimated 8.7 million plant and animal species are already shifting ranges in response to climate change. We can assume these percentages are higher in 2020. The article points out that this unprecedented species redistribution of life on Earth has numerous implications for both the impacted animals and human-well-being. In a broader sense, human and animal forced migrations due to climate change, coupled with ongoing population growth, mean that there will likely be many more instances of human encroachment on wild animal habitat. From the animal side, this loss of habitat can be devastating to already stressed species. From the human side, this means that interactions with wild animals with the potential to serve as zoonotic primary or intermediate hosts will likely increase—with the possibility of COVID-19 or similar, new diseases being passed back and forth between humans and animals. Infectious diseases can also operate through vector-borne transmission, and warmer temperatures can lead to vectors such as mosquitos inhabiting greater, or different, geographic regions. For these reasons, Sarah Zhang points out in a recent article in the Atlantic, The Coronavirus Is Never Going Away, that “the existence of animal reservoirs that can keep reinfecting humans is also why scientists don’t speak of ‘eradication’ for [zoonotic] viruses.”

What can we do? At the broadest level, researchers and policy makers need to work together. Just as human societies are going to have to find ways to accommodate massive human migrations caused by the changing climate so, too, should we consider what similar modifications might look like for animals. Along these lines, new management strategies are needed, and some researchers are calling for a more nuanced approach when it comes to flora and fauna that adjust their range to accommodate a warming world. One suggestion is to modify our definitions of “native” and “invasive” and adapt existing tools like the Environmental Impact Classification of Alien Taxa (EICAT) to assess potential risks associated with moving species. “Some people think that anything that’s not native is invasive, which isn’t necessarily the case.” says Stas Burgiel, Executive Director of the U.S. National Invasive Species Council (NISC). Because resources are limited and land management and conservation are publicly funded, Burgiel says, it is critical that the public understands how the decisions are being made. Furthermore, nations are going to have to work together to establish governance to deal with species redistribution beyond political boundaries. This is echoed by Pecl, et al. (linked above), who recommend that “with the predicted intensification of species movements and their diverse societal and environmental impacts, awareness of species ‘on the move’ should be incorporated into local, regional, and global assessments as standard practice.”
 
Another possible solution comes from a new opinion article, Ecological Fever: The Evolutionary History of Coronavirus in Human-Wildlife Relationships, in which authors Felipe Campos and Ricardo Lourenço-de-Moraes state firmly that “the coronavirus crisis results from the human disregard for biodiversity in their natural habitat and the wildlife trade spillover to spreading diseases. The substantial increase in deforestation of species-rich regions (e.g., Amazon forest and Southeast Asian forests) may be the beginning of a new pandemic.” Clearly, such deforestation contributes to the climate crisis as well. Campos and Lourenço-de-Moraes recommend that we highlight the need to preserve natural habitats of wildlife in order to prevent future pandemics, and to support conservation studies and efforts which explore the eco-evolutionary consequences of climate change in managing public health. 

Finally, while all of this might seem beyond our personal abilities to address, we can support those working on these issues. Those reading this already undoubtedly recognize our obligations to the world’s animals and the ecosystems that sustain them. Here and now we must realize that our human futures are linked to the Earth’s animals in ways that make the pandemic and climate crisis crucial to address. For humans and animals alike, our support for individuals and organizations who are attempting to tackle the connections between pandemics, the climate crisis, wildlife habitat destruction, and the migrations that are coming has never been more imperative.

MORE INFORMATION:
For more information on the connections between animals, climate change and global health check out:

Check out this series of six seminars with leading experts from around the world, produced by animalsclimatehealth.com with the aim of inspiring an in-depth conversation—and actions—at the nexus between animals x climate change x global health. Upcoming seminars consider Animals in Crisis, Animals Affected by Climate Change, and Animals as Drivers of Climate Change.

Oli Brown, n.d. Migration and Climate Change #31. Migration Research Series. International Organization for Migration. Geneva, CH.


Brett R. Scheffers and Gretta Pecl, 2019. Persecuting, protecting or ignoring biodiversity under climate change. Nature Climate Change, 9, 581-586.

Recorded sessions from the the 28th Annual Animal Law Conference: Impacts on Animals in a Changing Climate. Co-presented by the Animal Legal Defense Fund and Center for Animal Law Studies at Lewis & Clark Law School. October 2020.