By Erica Rychwalski

Imagine 350,000 square miles of back-to-back cities — roads, buildings, parking lots and not a lot of open space.

If you push together all the new urban areas humanity will build by 2030, this vision is exactly what you would see — a giant city covering the entire state of Texas.

But what does this staggering urban growth mean for nature and people? A lot — including species loss and declining natural resources such as fresh water — according to a new study co-authored by Conservancy scientists Robert McDonald and Peter Kareiva.

“While the effects of urbanization are very localized, cumulatively it is a big threat to biodiversity,” says McDonald, the lead-author of the study. “Our urban footprint covers much of the globe and is coming closer to stomping out many endangered species and posing new risks to protected areas and parks.”

And McDonald adds that governments and conservation organizations need to start planning for these trends — now.

Urbanization and Conservation

Humans officially became an urban species in 2007, according to the United Nations — with at least 50 percent of the world’s population currently living in cities.

By 2030, that number will jump to 60 percent, with nearly 2 billion new city residents, many migrating from rural areas. Humans are building the equivalent of a city the size of Vancouver every week.

Most of the growth is occurring in developing countries like China, India and Africa and in ecologically-rich, but threatened areas such as coasts and islands.

“As a species we have lived in wild nature for hundreds of thousands of years, and now suddenly most of us live in cities—the ultimate escape from nature,” says Kareiva. “If we do not learn to build, expand and design our cities with a respect for nature, we will have no nature left anywhere.”

In the study — published in the journal Biological Conservation — McDonald and fellow authors built scenarios of urban growth and examined how these models might affect ecoregions, rare species and protected areas through 2030. Their findings include:

• Ecoregions most affected by urban growth contain some of the highest concentrations of endemic species in the world — these places tend to be small, but significant. For example the Wimmer’s Shrew, found only in the outskirts of the capitol of Cote D’Ivoire on Africa’s west coast, will unlikely survive the expansion of Abidjan without some help from conservation.
• Eight percent of the vertebrate species of the IUCN Red List of endangered species are there largely because of urban development. And that number may continue to rise with new urban expansion and growth.
• Around 25 percent of the world’s protected areas will be within a day’s walk or half-hour drive of urban areas by 2030. Such proximity will increase the pressures on natural resources and intensify the threats to these protected places.

The Threat to Parks and Protected Areas

The data on protected areas may be the most alarming. The proximity of cities will increase the likelihood of resource extraction and other threats. As cities creep closer to these carefully protected areas and parks, they will cause changes such as:

• Different fire patterns as people tend to accidentally or intentionally start more fires as well as engage in more vigorous attempts to suppress fires that threaten human structures. Tijuca National Park near Rio de Janeiro, Brazil averages 75 wildfires a year, almost all caused by humans and most started at the edge of the park by surrounding residents.
• More invasive species. In Table Mountain National Park, South Africa, invasive plants are most frequently introduced near the edge of the park by wind or animals from backyard gardens.
• Poaching and illegal timber harvesting. Nearby towns are often the source of labor for illegal harvesting in response to regional or global market demands, as in the Barisan I Nature Reserve in West Sumatra.
• The decline of water quality and quantity. For example, Donana National Park in Spain is affected by dirty water from Sevilla, some 30 miles upstream.

“This is yet another vivid example of why conservation cannot simply be about sequestering nature in parks and reserves,” says Kareiva.

“We can set up all the reserves we want, but if we do not take care in where we place our cities, how we grow our cities, and how we live in our cities, then we will fail in our mission to protect biodiversity.”

Planning for Protection

Fortunately, according to McDonald, urban growth is a fairly predictable trend.

“Governments, city-planners and conservationists can work together to predict and plan in advance for some of these threats to nature,” he says. “Some species just have the bad luck of living where cities have been built. But by knowing our impact to these endangered species and protected areas, planners can start to shape the growth of cities to be more environmentally-friendly.”

However, a lack of funding, especially in developing countries, may prevent the implementation of smart-growth plans and expanded public transit systems — paving the way for more vehicles and drivers contributing more greenhouse gases to the atmosphere, a major cause of climate change.

“The structure of these cities will create long-term challenges for urban planners,” says McDonald. "And that could spell trouble for nature near these urban centers unless society rises to the challenge.”

McDonald is hopeful that this research and some of his follow-up studies will start those conversations between government officials and conservation scientists and encourage long-term planning.

“Only by addressing this growing conflict between cities and biodiversity can society achieve genuine conservation in an urbanizing world,” he says.

Erica Rychwalski is an associate director of marketing for The Nature Conservancy.

Nature picture credits (top to bottom, left to right): Photo © Scott Warren (Sao Paulo; Photo © Richard Herrmann (Development outside of San Diego, California).