EcoAlert: Are Mega Cities Accelerating the Planet’s Biodiversity Crisis? (Today’s Most Popular)

Metropolis_above_2_2 "Every week humans create the equivalent of a city the size of Vancouver."

A new study outlines the uncomfortable question of what happens to the planet’s biodiversity when cities take over the world. Cities are growing, and they’re growing fast. It is projected that urban growth will create an additional 350,000 square miles of cities roads, buildings and parking lots—covering a combined area the size of Texas—by 2030. Every week humans create the equivalent of a city the size of Vancouver. What will this staggering growth mean for both nature and people?

According to the study, co-authored by Conservancy scientists Robert McDonald and Peter Kareiva McDonald, it means significant species loss and a further decline of natural resources like fresh water. They say we need to prepare—now.

“While the effects of urbanization are very localized, cumulatively it is a big threat to biodiversity,” says McDonald, 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.”

According to McDonald, governments and conservation organizations need to start planning for these trends immediately. Why? Because its a lot easier to design urban growth well in the first place, then it is to try and change it after the infrastructure has already been laid. By then it’s usually too late.

According to the United Nations, humans officially became an urban species in 2007 when a milestone was reached. Over half of the world’s population now live in cities. By 2030, 60 percent of the world’s citizens, including nearly 2 billion from rural migration, will be living in cities.

“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.”

Indeed, biocide is occurring at an alarming rate. Experts project that at least half of the world’s current animal species will be completely gone by the end of the century. Wild plant-life is also disappearing. Most biologists say that we are in the midst of an anthropogenic mass extinction that is at least partially caused by human encroachment on more and more areas of the planet. Numerous scientific studies confirm that this phenomenon needs to be addressed quickly.

McDonald’s study, published in the journal Biological Conservation, confirms what other experts have found: Wildlife is in trouble. The research projects urban growth scenarios, including how these models could affect ecoregions, rare species, and protected areas up until 2030. Here is a summary of some of their findings:

Around 25 percent of the world’s protected areas will be only a half-hour drive from an urban metropolis. Such proximity will increase the pressures on fragile natural resources and intensify the threats to protected ecosystems.

As cities start to creep up on protected areas and parks, they will likely change fire patterns as more people accidentally or intentionally start fires, as well as engage in more ecologically damaging attempts to hamper fires that threaten human structures. For example, Tijuca National Park near Rio de Janeiro, Brazil averages 75 wildfires a year. Nearly all of them are caused by humans living near the edge of the park.

Invasive species will increasingly take over native flora and fauna. In Table Mountain National Park, South Africa, for example, invasive plants are usually introduced from backyard gardens bordering the park.

Poaching and illegal timber harvesting will also increase as nearby towns respond to regional and/or global market demands, such as is now occurring in the Barisan I Nature Reserve in West Sumatra.

Water quality and quantity will continue to decline due to nearby urban growth, such as is currently happening in Donana National Park in Spain where dirty water from Sevilla, which is 30 miles upstream, pollutes the parks formerly pristine waters.

“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.”

On the bright side, McDonald says that urban growth is following a fairly predictable trend, so it’s not too late to start mitigating certain effects in advance.

“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.”

One challenge, especially in developing countries, is the lack of funds allocated towards smart planning practices. But regardless of where the threats are occurring, continued biodiversity is something the entire world needs to stand behind.

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

Rebecca Sato



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