Growth of cities endangers global environment

Aug 19, 2011

The explosive growth of cities worldwide over the next two decades poses significant risks to people and the global environment, according to a meta-analysis published today in Plos One.

Researchers from Yale, Arizona State, Texas A&M and Stanford predict that by 2030 urban areas will expand by 590,000 square miles—nearly the size of Mongolia—to accommodate the needs of 1.47 billion more people living in urban areas.

"It is likely that these cities are going to be developed in places that are the most biologically diverse," said Karen Seto, the study's lead author and associate professor in the urban environment at the Yale School of Forestry & Environmental Studies. "They're going to be growing and expanding into forests, biological hotspots, savannas, coastlines—sensitive and vulnerable places."

Urban areas, they found, have been expanding more rapidly along coasts. "Of all the places for cities to grow, coasts are the most vulnerable. People and infrastructure are at risk to flooding, tsunamis, hurricanes and other environmental disasters," said Seto.

The study provides the first estimate of how fast urban areas globally are growing and how fast they may grow in the future. "We know a lot about global patterns of urban population growth, but we know significantly less about how urban areas are changing," she said. "Changes in land cover associated with urbanization drive many environmental changes, from habitat loss and agricultural land conversion to changes in local and regional climate."

The researchers examined peer-reviewed studies that used satellite data to map urban growth and found that from 1970 to 2000 the world's urban footprint had grown by at least 22,400 square miles—half the size of Ohio.

"This number is enormous, but, in actuality, urban land expansion has been far greater than what our analysis shows because we only looked at published studies that used satellite data," said Seto. "We found that 48 of the most populated have been studied using satellite data, with findings in peer-reviewed journals. This means that we're not tracking the physical expansion of more than half of the world's largest cities."

Half of urban land expansion in China is driven by a rising middle class, whereas the size of cities in India and Africa is driven primarily by population growth. "Rising incomes translate into rising demand for bigger homes and more land for urban development, which has big implications for biodiversity conservation, loss of carbon sinks and energy use."

Explore further: Yale journal explores advances in sustainable manufacturing

More information: The paper, "A Meta-analysis of Global Urban Expansion," can be viewed on the Plos One website at dx.plos.org/10.1371/journal.pone.0023777

Related Stories

Ecological impact of African cities

Dec 02, 2008

African cities are growing faster than anywhere else in the world. This is having a major impact, but few ecologists are studying the urban environment and effect of cities on rural areas. One of the most important ecological ...

There's a change in rain around desert cities

Jul 26, 2006

Urban areas with high concentrations of buildings, roads and other artificial surface soak up heat, lead to warmer surrounding temperatures, and create "urban heat-islands." This increased heat may promote ...

'Satellites and the city'

Jul 21, 2005

Just how does society's desire to live in densely populated areas have the potential to change our Earth's climate? According to a new paper, satellites can help us answer that question.

Recommended for you

User comments : 8

Adjust slider to filter visible comments by rank

Display comments: newest first

Moebius
1 / 5 (1) Aug 19, 2011
Especially the biggest city of all, China.
Nanobanano
Aug 19, 2011
This comment has been removed by a moderator.
Scottingham
2 / 5 (1) Aug 19, 2011
Perhaps indoor multistory hydroponic farms could help mitigate the effect these cities have on the land around them.

They'd need a lot of energy though, a source of energy that doesn't require hundreds of thousands of acres.

Start crackin' them atoms!
Nanobanano
2 / 5 (2) Aug 19, 2011
Perhaps indoor multistory hydroponic farms could help mitigate the effect these cities have on the land around them.

They'd need a lot of energy though, a source of energy that doesn't require hundreds of thousands of acres.

Start crackin' them atoms!


One of the ideas I had was to use off-shore floating farms in areas of the ocean which are hypoxic anyway. Since nothing grows there, having floating platforms on which you grow food crops would not affect the natural environment all that much anyway.

Nuclear isn't really needed for hydroponics farming, even with world population swelling significantly.

Something else, the gulf stream between Florida and Bahamas flows at between 1.5m/s and 2.5m/s. A water turbine at 30% efficient should be able to harness anywhere from 500 to 2300 watts/m^2 of turbine area.

I don't know why Florida isn't using this to power the Keys and Miami. This is the most energy dense form of solar energy on earth.
omatumr
1 / 5 (5) Aug 19, 2011
Almost two years ago released e-mail messages confirmed our worse suspicions about the AGW story and the environmentalist movement.

World leaders and leaders of scientific organizations and the news media have closed ranks in defending data manipulation and outright deceit as good government science.

Frankly I think it is time for citizens worldwide to close ranks with the Australians [1,2] in demanding an end to tyranny and a return of the basic human right for citizens to control their government!

1. JoNova's blog:

http://joannenova...ensland/

2. "No Confidence Rally", The International News Magazine

www.international...ce-rally

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo
Nexus789
5 / 5 (5) Aug 19, 2011
An inability to deal with the elephant in the room - excessive and destructive population growth will result in economic and social collapse for two reasons - finite resources compounded by unequal distribution of what we do have.

Land, habitat, etc, destruction by the growth of cities is just a by-product.
Sean_W
1 / 5 (2) Aug 20, 2011
Meta-analysis = mating call of the red-breasted big fat liar.
_nigmatic10
not rated yet Aug 20, 2011
the flip side to this is the increase in resources to build and the increase in farm land to feed. Why do i feel a hit piece out of this article. More alarmism?
MarkyMark
5 / 5 (1) Aug 21, 2011
Almost two years ago released e-mail messages confirmed our worse suspicions about the AGW story and the environmentalist movement.

World leaders and leaders of scientific organizations and the news media have closed ranks in defending data manipulation and outright deceit as good government science.

Frankly I think it is time for citizens worldwide to close ranks with the Australians [1,2] in demanding an end to tyranny and a return of the basic human right for citizens to control their government!

1. JoNova's blog:

http://joannenova...ensland/

With kind regards,
Oliver K. Manuel
Former NASA Principal
Investigator for Apollo

Jeez what is it with you !!!