Quiz: What You Don't Know About Cities and Energy


Photograph by Jim Richardson, National Geographic

You know it takes power to make the lights of the metropolis glimmer, but how much do you really know about cities and energy?

The world's cities occupy about 2 percent of the land on Earth. About what percentage of the world's greenhouse gas emissions can be attributed to cities?

  • 10 percent
  • 20 percent
  • 50 percent
  • 70 percent

The United Nations estimates cities are responsible for 70 percent of harmful greenhouse gas emissions.

On a per-person basis, greenhouse gas emissions in cities are often far below the national average, thanks to public transit, density and smaller living spaces. But which of the following cities has higher per-capita emissions than its nation's average?

  • Seoul
  • Beijing
  • New York
  • Brussels

Beijing's per-capita carbon emissions exceed those of China as a whole because so much of the rest of the country is less developed than the capital.

In the Kangnam section of Seoul, what home energy-saving measure is visible from the outside?

  • Buildings are close together.
  • Reflective glass is used for windows.
  • Buildings are spaced far apart.
  • Buildings face south.

Apartment buildings are lined up like soldiers on parade, as one urban planner describes it, in an effort to maximize warmth from south-facing windows. Koreans prefer to keep their apartments warm, yet the nation is heavily dependent on energy imports.

Which large U.S. city had the largest share of working-age residents with close access to mass transit in 2011?

  • Honolulu
  • Chicago
  • New York
  • Boston

Thanks to Honolulu's TheBus system, the city's constrained geography, and centralized employment base, 97 percent of the city's adults are within three-quarters of a mile of a transit stop, the best coverage among U.S. cities, a Brookings Institution analysis concluded.

What year did New York establish Broadway at Times Square as a car-free zone?

  • 1928
  • 1972
  • 2009
  • 2011

On Memorial Day 2009, New York began an experimental pedestrian plaza on Times Square, a change made permanent the following year after statistics showed an improvement in traffic patterns and significant decline in pedestrian and motorist injuries. Nitrogen oxide emissions also have dropped precipitously in Times Square.

A survey of more than 430 U.S. cities showed that the average automobile commuter spent 34 hours stuck in traffic congestion in 2010. How much gasoline was wasted, or burned while idling, as a result for each driver?

  • 1 gallon (3.8 liters)
  • 4 gallons (15 liters)
  • 14 gallons (53 liters)
  • 40 gallons (151 liters)

The average U.S. urban commuter wasted 14 gallons (53 liters) of gasoline while idling in traffic congestion in 2010, according to the Texas Transportation Institute's analysis. The study said that adds up to 1.9 billion gallons of waste—or two months' flow from the Alaska oil pipeline.

Automobile traffic declined 20 percent in London in the first few months after it implemented a congestion charge program—tolls for vehicles entering the city's center—in 2003. What has happened to traffic since?

  • It has declined another 20 percent, as of 2011.
  • It has stayed relatively stable.
  • It has returned to levels seen before the congestion charge.
  • It has increased 20 percent above congestion charge levels, as of 2011.

Transport for London says congestion has risen back to the levels seen before the charge began, which it blames in part on reduced road capacity due to widespread utility work. But the city agency says congestion would be much worse without the charge.

A 2011 Stanford University study considered the urban heat island effect and its impact on global warming. What did the researchers conclude?

  • It is a far more significant contributor to global warming than fossil fuel emissions.
  • It is as significant a factor in global warming as fossil fuel emissions.
  • It is a far less significant contributor to global warming than fossil fuel emissions.
  • It plays no role as a contributor to global warming.

The researchers concluded that the excess heat released by cities (compared to vegetated areas) is responsible for between 2 and 4 percent of the gross global warming since the Industrial Revolution. In contrast, greenhouse gases contributed 79 percent; black carbon, about 18 percent.

Rotterdam, in The Netherlands, ranked as highest among 100 global cities in terms of greenhouse gas emissions per person, according to a 2011 study. What is the most likely factor accounting for the city's high fossil fuel emissions?

  • It is a port city.
  • It has a relatively large population.
  • It has a relatively young population.
  • It has relatively cold temperatures.

As Europe's largest port, and a trading hub for petroleum products and major ship refueling center, Rotterdam has higher per-capita emissions than other cities of similar size or climate, researchers found.

In 2011, Beijing faced pressure from critics because of a practice they said underestimated air pollution due to fossil fuel emissions. What was the practice?

  • Only tracking large particle pollution
  • Only tracking small particle pollution
  • Not tracking smokestack pollution
  • Not tracking automobile pollution

Beijing meteorological authorities were delivering “good” air quality readings at the same time the U.S. embassy in Beijing gauged pollution to be at “hazardous” levels, because the city was tracking only coarse particle pollution, and missing fine particles released by petrochemical industries and vehicles.





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