Widespread public discussion and agreement will be needed to achieve this agricultural goal for the world. With more than 80 percent of Americans living in cities and more than 60 percent of people in urban environments worldwide, we must educate urbanites about the ecosystems they depend on so they can participate in democratic processes that will lead to successful solutions for the problems of the Anthropocene.
With such a large urban population, the most common contact humans have with plants is through horticulture in city landscapes. Therefore, we must improve our horticultural design and management in urban centers so as to provoke thoughtful and accurate understanding of the often invisible agricultural and other ecosystems that sustain us. In other words, we must garden wisely in the cities so that we will know how to extend that wisdom to the rest of the planet.
Horticulture has traditionally been design driven, with its applied science dimension a means to achieve a desired aesthetic. In the Anthropocene, horticulture must reprioritize so that every landscape is not only pleasing and artistic but also demonstrative and functional as a complete ecosystem.
The traditional concept of beauty in a garden must change. Gardens are often judged by their tidiness, with everything seeming clean and neat. All fallen leaves and branches are removed and each plant is assigned a distinct location. Yet fallen leaves provide cover for roots and habitats for insects and fungi and add to the overall richness of the site while building soil. We must move from expecting gardens to be so tightly controlled and static to requiring that they represent ecosystem processes (e.g., biogeochemical cycling, succession, and evolution). To achieve environmental and horticultural goals, landscape design and architecture must integrate ecological principles with creative garden design so that ecosystem-based gardens can also be aesthetically pleasing. In addition, agriculture must be embedded within urban horticulture in a way that demonstrates how extensive agricultural systems function. Urban agriculture has become an important trend that offers urbanites community cohesion and an exciting introduction to the principles and science of food production, although it enhances food security only in limited circumstances. While urban agriculture will certainly become an enduring feature of cities, we must also make a concerted effort to bring the highly productive agricultural landscapes of the extensive rural lands into the urban tapestry. This more extensive, “agriculture in an urban setting” approach has the potential to present urbanites with realistic scenarios for provisioning all people with food while coexisting in harmony with functional ecosystems and reinforcing the fact that cities are dependent on lands very much out of sight.
Horticulturists and landscape designers must learn how to mimic natural ecosystems and production agriculture in cities. Among other benefits, this will teach citizens what these systems are and how they work. Such urban gardens, by creating the opportunity for education about agriculture and wildlands, foster inclusive and democratic decision making. These practices also increase the environmental integrity of the city itself, by promoting landscapes that reduce pollution, process clean water, support wildlife, and provide beauty and serenity for inhabitants. Ideally, people will no longer think of urban plantings as static design elements but rather as complex, regenerative, and evolving ecosystems. Through designed horticultural mimics, these gardens will open the eyes of the general public to the biological processes governing agricultural and natural ecosystems. We should all realize that our management of both the easily visible landscapes in the cities and the hidden landscapes dominating the rest of the planet holds the key to both our own future and the future of the planet.
As the University of Pennsylvania ecologist Dan Janzen pointed out a half-century ago, “The world is a garden, and we’re all its gardeners.” Along with achieving a stable population and socially justifiable levels of consumption, we must evolve our gardening to fit sustainably and securely into the global system. If we fail to feed our unprecedented and growing population, people will suffer and die. If we fail to adapt our agriculture and horticulture practices to alleviate the pressures we are putting on the environment, a huge proportion of biodiversity that now exists will be lost forever. The clock is ticking, yet reasons for optimism exist, as evidenced by our continued survival as a species and our increase in food security over the past century. We need to start paying much closer attention to our planted planet; as Voltaire’s Candide said, “We must cultivate our garden,” though in our case we must also act quickly and wisely.
HUMAN HEALTH IN THE ANTHROPOCENE
GEORGE E. LUBER
As humans entered the Holocene epoch, marked by the end of the last major glacial advance, or ice age, some 11,700 years ago, a planetary transformation began to occur. Increasingly, people lived in permanent settlements, moved away from foraging and hunting for food, and made farming the major mode of subsistence. In the intervening millennia, much of the planet has changed as a result of the quickening pace of human activity and population growth. Today, almost a third of Earth’s arable land has been converted to cropland or pasture, more than 90 percent of monitored fisheries are harvested at or above sustainable yield limits, about half of annual available freshwater is appropriated for human use, and species extinction rates are more than a hundred times greater than has been observed in the fossil record.
Perhaps the most startling of all of these global transitions has been the profound alteration of Earth’s atmosphere; concentrations of major greenhouse gases—carbon dioxide, methane, and nitrous oxide—are at their highest level in more than eight hundred thousand years, in large part due to the burning of fossil fuels and large-scale land-use changes. The scope and scale of these planetary changes have prompted several in the scientific community to call for the designation of a new epoch, the Anthropocene.
While many of the planetary changes that the Anthropocene represents have consequences for human health, perhaps none will have as broad and transformative an impact as climate change. From weather extremes that directly cause injury or death to potentially profound changes in disease ecology and geography brought about by large-scale state shifts in Earth’s ecosystems, climate change will be among the defining issues for public health in the twenty-first century.
Climate change poses a threat to human health in a variety of ways: injury and death from heat waves, extreme storms, and reduced air quality from increasing ozone, aeroallergens, and drought-related wildfire smoke; illnesses transmitted by food, water, and vectors such as mosquitoes and ticks; and mental health impacts subsequent to disasters. More important, climate change will threaten the critical systems and infrastructure we rely on to keep us safe and healthy: communication and transportation during emergencies, food and water systems during drought, energy grids during prolonged heat waves. As the magnitude and frequency of extreme weather events increase, the resilience of these systems will be tested, and vulnerabilities will be exposed. It is in this sense that climate change will serve as a risk multiplier, amplifying both the exposures that bring about health risks and the vulnerabilities to these exposures.
While climate change will be an important driver of human health, it does not work independently. Other trends that define the Anthropocene—such as urbanization, pollution, and land-use change—will work together with climate change to intensify the threats to human health. Perhaps the most defining feature of the Anthropocene for humans will be the dominance of the urban setting as the primary habitat for large populations. Today, more than half of the planet’s population lives in cities; fifty years ago, that number was only 30 percent. This unprecedented and rapid urbanization has led to a landscape transformed from native vegetation to an engineered built environment, resulting in significant differences between the urban climate and adjacent rural regions, a phenomenon known as the urban heat island (UHI) effect.
The UHI can exert a strong influence on local climate. The combined effect of the high thermal mass provided by concrete and blacktop roads, the exaggerated rainwater
runoff resulting from the scarcity of permeable surfaces, the low ventilation ability of the urban “canyons” created by tall buildings, and the point-source heat emitted from vehicles and air conditioners magnifies the multitude of impacts brought about by climate change. The health consequences of heightened UHI exposure include rises in both heat-related illness and respiratory illness due to an increase in tropospheric ozone and particulate matter. In a real sense, cities and climate are coevolving in a way that serves to amplify the health hazards resulting from extreme heat, degraded air quality, heavy precipitation runoff, and coastal storms.
In addition to the UHI effect, cities are sources of emissions, as a result of the high density of their housing, motor vehicles, and industry. This combination creates what is called the urban CO2 dome: higher carbon dioxide levels in cities than in the surrounding rural areas. While climate change is expected to alter the spatial and temporal distribution of several key allergen-producing plant species by lengthening their growing season and shifting their distribution northward, increased atmospheric carbon dioxide concentrations, independent of weather and climate effects, have been shown to stimulate pollen production. A series of studies found an association between elevated urban carbon dioxide concentrations in Baltimore and faster growth and earlier flowering of a ragweed species (Ambrosia artemisiifolia), along with greater production of ragweed pollen, leading, in some areas, to a measurable increase in hospital visits for allergic rhinitis. Other studies have shown that poison ivy (Toxicodendron radicans), another common allergenic species, responds to high carbon dioxide levels with increased growth and biomass. Its reaction exceeds that of most other woody species and also results in a more potent form of the primary allergenic compound urushiol.
Urban areas also focus risks to their populations from climate change by virtue of where they are located. Cities tend to be found in specific topographic settings: in valleys or basins, at low elevation, and, especially, near coasts. About 40 percent of the U.S. population lives in coastal cities, which are at increasing risk of multiple related threats, including heat waves, flooding from heavy rainfall events, and inundations caused by a combination of sea-level rise, storm surges, and heavy rainfall—all functions of climate change. Their vulnerability increases when the effects of climate change interact with preexisting stressors, such as aging infrastructure, high population density, and poverty. The potential failure of critical components such as water and sewage systems, roads, bridges, communication networks, and power grids increases with climate change and can result in significant threats to health.
Responding to the emergent threats posed by climate change, urbanization, vulnerable infrastructure, and demographic transition—hallmarks of the Anthropocene—requires rethinking the types of actions and policies we adopt to manage the harmful exposures associated with these trends and each population’s underlying vulnerability to them. An integrated, health-focused co-benefits approach can provide opportunities to improve environmental conditions while promoting healthy behavior. Its actions and policies can take many forms, including large-scale efforts to decarbonize power generation, “green” urban infrastructure, and transform communities to foster active transportation, and individual-level behavior-change efforts to promote low-carbon, healthy lifestyles.
For example, transitioning to solar, geothermal, or wind power not only reduces greenhouse gas emissions but also improves regional air quality, with benefits to respiratory and cardiovascular health. Policies to promote active transportation, by providing bike paths, walkable communities, and mass transit, not only lower motor vehicle emissions but also promote physical activity, with direct benefits to cardiovascular health and obesity prevention. More-connected, walkable communities can also reduce social isolation, especially among the elderly, which has been shown to be an effective strategy to protect those most vulnerable during heat waves. Individual behaviors such as adopting a plant-based diet can also help reduce the large greenhouse gas footprint of livestock production while reducing the risk of cardiovascular disease and some types of cancers associated with a diet high in red meat. Certainly, many of these policies will have large economic costs, but so does the true burden, often unacknowledged, of carbon emissions on human health and infrastructure. And these policies may be the best way to address the threats posed by the Anthropocene.
The global transformation of our planetary systems, what we are calling the Anthropocene, is increasingly evident and stands to bring substantial challenges to Earth’s future. These include climate change, urbanization, difficult demographic trends, and habitat loss and fragmentation. These transformations cannot be looked at as independent phenomena and studied alone but must rather be considered as an intersecting and coevolving set of drivers with great significance for planetary, and human, health.
Steady planetary change lacks the visual drama of singular catastrophic events, such as the types that inspire Hollywood movies or paintings of volcanic eruptions. The gradual pace and invisibility of threats such as ocean acidification and biodiversity loss increase the challenge for artists seeking to communicate about environmental change. Essays in this section describe a variety of approaches. The paintings of the American artist Alexis Rockman imagine an urbanized world transformed by extreme climate alterations and underscore the futility of human efforts to battle nature. In contrast, contemporary African artists document the continent’s ubiquitous environmental disruptions while campaigning against socially and ecologically unsustainable choices. In the Arctic, where global warming’s early impacts have been the most pronounced and where indigenous peoples have disproportionately borne the detrimental effects, depictions of polar bears over the past half century illustrate how local artistic engagement with climate change has shifted from an initial celebration of life to mourning and a call for political action. Visual expression via film and video offers other ways to engage audiences. Recognizing that people are more likely to support the conservation of objects and species they have come to care about, makers of natural history documentaries, for instance, are learning to balance messages of despair and hope in ways that encourage action and discourage cynicism. In the mass media, where communication of scientific information can be more wholesale than retail, the images and metaphors of visual culture provide essential tools for conveying the complex and often counterintuitive impacts of human activities on Earth’s biogeochemical systems. The contributions of artists can stir our collective imagination, capture deep anxieties about degradation of the environment, and fuel the empathy that will be invaluable to attaining a just and sustainable future in an increasingly uncertain world.
THE CITY IN THE SEA
ALEXIS ROCKMAN’S ANTHROPOCENE IMAGININGS
JOANNA MARSH
Modern megacities are among the most conspicuous signs of the Anthropocene. Towering centers of glass, concrete, and steel have altered the surface of Earth in previously unimaginable ways. One hundred years ago, only 10 percent of the world’s population lived in cities, but it is estimated that by 2050, nearly 75 percent of people on the planet will live in a major urban center. This unimpeded growth of the world’s cities coincides with climate extremes previously unseen by humanity—heat waves, intense rainfall, and rising sea levels. Cities are at the forefront of global climate change, in both its causes and its effects. Greenhouse gas emissions and energy demand are highest in metropolitan centers, which are also more vulnerable to extreme climate events caused by warming temperatures. In short, the modern megacity has increased the threat of megadisasters. Many experts believe that urbanization and climate change are on a collision course that will either spur new, more sustainable living solutions or exacerbate resource scarcity and endanger already vulnerable communities. As the journalist Gaia Vince writes, “The urban revolution of the Anthropocene could prove to be the solution to many of our environmental and social problems….Or, it could finally prove to be our species’ undoing, the apocalyptic version of the dystopi
an megacity so often portrayed in science fiction.”
The artist Alexis Rockman is well versed in these alarming statistics and dire environmental predictions. Over the past twenty-five years, he has created an extensive body of work that combines art, history, science, and popular culture to comment on the myriad ways that humans have altered the planet, from deforestation and biodiversity loss to genetic engineering. Long before Paul Crutzen coined the term Anthropocene, Rockman was giving visual form to the transformations—visible and invisible, real and imagined—that have come to characterize the Age of Humans. His vivid paintings imagine a familiar yet fictional world, anchored in disturbing reality.
Among the many locales that he has depicted over the years, New York City holds a special attraction for Rockman. The artist was born and raised there and continues to live and work in the city. He spent his childhood exploring the exhibit halls of the American Museum of Natural History, where he developed a passion for science and natural history. His early work frequently references the displays and dioramas that he saw there, but in recent years the city itself has become a recurring subject. Rockman’s first major painting of New York City, Manifest Destiny (2004), was also his first work to directly confront the climate crisis and its toll.
Now in the collection of the Smithsonian American Art Museum, Manifest Destiny presents a postapocalyptic vision of Brooklyn several hundred years in the future. The borough is inundated by floods or rising sea levels that have rendered the metropolis a semitropical water world. Rockman drew upon extensive scientific research, including consultations with ecologists, climatologists, urban planners, and architects, to create his image of a future New York. This convergence of scientific thought and visionary premonition recalls the style of science-fiction storytelling—a major influence on Rockman’s work.
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