
By Kristina Hill, Affil. ASLA
The close friendships people make during the intensity of design school often last a lifetime. My studio bestie was a funny, talented guy named Merrick Zirtzman. We were like twins, except that he contracted AIDS and I didn’t. We ate garlic cloves together and tried to stay safe. But he died within two years of our graduation, along with about 700,000 other Americans who lost their lives to AIDS.
Subsequent research determined that HIV originated in chimpanzees in West Africa, showing that it became a human disease because humans ate chimpanzees. According to Michael Lai at the University of Southern California and his team of disease detectives, the chimps got it by eating monkeys that hosted a similar virus (red-capped mangabeys and greater spot-nosed monkeys, to be exact). This sounds like a version of saying you are what you eat: a food web in an ecosystem of viruses, hosts, predators, and habitat.
When I wrote and spoke about the research connecting biodiversity to infectious diseases in the late 1990s and early 2000s, I was one of very few in our field who would broach the subject. At the time, if HIV/AIDS hadn’t roared through your friends, a pandemic seemed unlikely. Worrying about it seemed paranoid. After all, people said, contemporary medicine has made so many advances!
The last time I spoke about biodiversity and its role in suppressing pandemics was at the Large Parks conference at Harvard University in 2004. After that, my work centered on adapting to climate change, and there was so much other science to talk about. Eventually, pandemics dropped out of my slide set.
Every year, the World Economic Forum organizes a gathering of the global 1% in Davos, Switzerland, and produces a document to communicate the anxieties of money managers, called the Global Risk Report. In 2019, the Global Risk Report had a special section on health risks, titled “Going Viral.” It noted that there has been an increase in the frequency of new infectious disease outbreaks over the last few decades. There were more than 12,000 outbreaks between 1980 and 2013. But in June 2018, there were outbreaks in six of the eight categories of the especially dangerous priority diseases tracked by the World Health Organization (WHO).
For the first time, WHO included “Disease X” in its 2018 list of priority diseases to promote research on new zoonotic diseases that had not yet passed to humans. People who track diseases were expecting new ones, because the number of animal-to-human outbreaks has increased dramatically. The UN Environment Program also stated that a new infectious disease emerges in humans every four months now, and that 75 percent of those come from wild or domesticated animals.
The 2019 Davos Risk Report noted five main reasons for this alarming trend:
- First, huge increases in the volume of inter-continental travel make it possible for a virus from an isolated village to infect major cities within days.
- Second, an increasing percentage of the world’s growing population lives in dense urban districts.
- Third, people are cutting the forests that provide habitat for animals like bats and primates that carry diseases, which humans can catch.
- Fourth, climate change may accelerate disease transmission by extending the range of some key animal vectors, like mosquitos, but in other complex ways as well.
- And fifth, poverty drives a lot of people to hunt bushmeat or to raise undernourished domestic animals.
Also, desperate refugees trying to escape wars or climate stressors often live in dense, unhygienic conditions created by societies who want to keep them out, producing hotspots of infectious diseases. The 2019 Risk Report concluded that “globalization has made the world more vulnerable to societal and economic impacts from infectious-disease outbreaks.”
Remember, this isn’t ecologists talking, this is the 1%, the people who spent the last 400 years profiting from the removal of “barriers” to global markets and building a world of white privilege through racism, armed colonization, and enslaved labor. Not to put too fine a point on it.
Ecologists who write about the links between biodiversity and disease typically emphasize the need to limit human impacts on animals that harbor the greatest number of viruses that can spillover to humans: waterfowl, primates, and bats.
When E.O. Wilson published Half Earth: Our Planet’s Fight for Life in 2016 and established the Half Earth Project, it sounded crazy to economists and governments to say we should protect half the earth’s land and seas from development.

Even sociologists who focus on poverty and development, like Bram Büscher and Robert Fletcher, slammed Wilson’s proposal. They saw it as a trade-off: protect biodiversity at the expense of the rural poor, who would then be arrested as poachers in their own traditional lands.
But social inequality will not be erased if biodiversity losses continue. Less biodiversity means more disease pandemics and more poverty. I think we can all see that now.
In the 21st century, globalized economic growth has reached the end of its rope. Economies can’t continue to expand without creating new pandemic risks, as more people press up against the habitat of more wildlife or raise domestic animals in unhealthy conditions. We’re now part of one big, highly connected planetary ecosystem that’s going to bite us back hard if we step on it the wrong way.
A lot of news stories are ascribing intention to viruses as if they make plans. While that creates a compelling bad guy, they’re not actually living things. We’re the sentient beings here.
New planetary health concepts advocated by many non-governmental organizations (NGOs) provide the framework we need to see through metaphors about viruses invading our country with evil intentions, and the associated imagery of a refugee invasion from some place we imagine to be far away, disconnected from us. In fact, the U.S. is a global hotspot of emerging animal-to-human diseases.
What does this mean for landscape architecture, as a discipline that shapes urban and regional planning?
The challenge is to use our projects and our advocacy to fight for biodiversity (if only for our own survival), genuinely reduce economic inequality, and promote a culture that celebrates rather than denies the inherent limits to growth that come with sharing a single planet.
As Kate Jones, Chair of Ecology at University College London, has noted, pandemics are now “a hidden cost of human economic development…We are creating habitats where viruses are transmitted more easily, and then we are surprised that we have new ones.”
Landscape architects and planners can take on this work in three important ways:
First, we can educate clients about the role that native habitat plays in preventing disease outbreaks. Here in California, recent research has revealed that our low rate of Lyme disease can be attributed to our remaining biodiversity. Both mountain lions and western fence lizards play key roles in limiting Lyme disease. Lions keep the deer population low, especially near urban areas where they kill fifty percent more deer per year, perhaps because they are interrupted in the act of eating their kill more often by humans. Our native lizard has proteins in its blood that seem to “turn off” the infection in ticks that bite the lizards, creating a less dangerous tick population that doesn’t host the Lyme bacteria. None of this would work if there were no lion or lizard habitat, no lions, and no lizards.

We can work to genuinely promote social equality. Step one is to stop pretending that development investments, or even new parks, create benefits for everyone. In fact, investments in parks typically displace low-income residents (anyone been to the High Line?). Setha Low’s anthropological research in New York City showed that upscale materials or finishes, like brushed aluminum or polished rock, can make lower-income people of color feel unwelcome, setting them up to be followed and harassed because Caucasian park visitors think they don’t belong there. Creating new upscale mixed-use districts in historically African-American, Native American, and Hispanic spaces raises the likelihood that police will kill more people of color. Trickle-down public benefits from private real estate investments are a myth. We can stop repeating it and instead work to increase the health, wealth, and stability of low-income communities directly. In the San Francisco Bay Resilient by Design Challenge, our ABC Team re-thought our work in East Oakland to focus more on supporting local businesses and health, rather than trying to imagine the trickle-down benefits of big new real estate investments.
Third, we can promote a culture of restraint to protect local habitat areas. Persuading humans to back off and respect the territory of other cultures or other forms of life is the real “balance of nature,” created by our own sense of restraint. We can design windows in “walls” that surround key vegetated areas, instead of designing paths through them. Maybe these are literal walls, like the habitat island at Parc Henri Matisse in Lille, France by Gilles Clément. Or maybe they’re thorny hedge plants or wetland “moats” with an overlook platform. Physical trampling, noise, and pets exert real limits on biodiversity. And cultural self-restraint can be sexy—it can be theatrical and negotiated. Not going somewhere can make that special place valuable and mysterious. Bring back the sacred Greek temenos, and the hortus conclusus. Limits and social negotiation create deeper design opportunities and better designers.

There’s more: are you designing new urban districts in China, Africa, or the Middle East? It’s time to reconsider taking that work unless it’s an infill strategy.
And we should all stop flying so much, considering its impact on our climate and our health — and now that we’ve mastered Zoom.
Prevent urban and agricultural sprawl into native vegetation. Promote increased wealth and self-sufficiency for the global poor. Support animal welfare by becoming an activist against large-scale animal farming.
Landscape architects can lead a re-think of how to design for biodiversity, cities, and health on our one little planet.
Kristina Hill, Affil. ASLA, is associate professor of landscape architecture, environmental planning, and urban design at the University of California at Berkeley College of Environmental Design.
Kristina’s prescription is absolutely “right on!” It should become the mantra for all that we do as LA professionals.