As the 2012 Summer Olympics get underway this weekend, the world's attention will be focused on London.
But a team of scientists has recently been keeping a very close eye on the city that hosted the games four years ago: Beijing.
They've discovered that China's efforts to cut back on traffic and clean up its air during the 2008 Olympics could have big implications for curbing climate change.
A recent study published in the journal of Geophysical Research Letters shows that Beijing's traffic restrictions during the games led to a significant reduction in emissions of a powerful greenhouse gas: carbon dioxide (CO2).
An international team of scientists led by the National Center for Atmospheric Research in Boulder, Colorado used satellite instruments and computer models to measure what happened to Beijing's CO2 emissions before and after the Olympic games.
In addition to shutting down factories and scaling back construction work, Chinese officials implemented a 50 percent ban on private vehicles during the Olympics. Beijing motorists were restricted to driving every other day.
The researchers found that the traffic restrictions alone cut CO2 emissions by up to 96,000 metric tons. That represents about one quarter of one percent of what would be needed on a global scale to prevent the planet from heating up by 3.6 degrees Fahrenheit by the end of the century.
"A quarter of a percent might sound like a small number, but this is just one city," says Helen Worden, lead author of the study. "If urban traffic was reduced globally, then it might start to make a big difference."
Beijing is among the most populous metropolitan areas in the world. Worden says it's obvious that cutting traffic reduces CO2 emissions, but this was a unique opportunity to measure just how much.
"We could see the differences from space ... It was very interesting in terms of what happens when one city cuts its traffic by half," she says.
It's hard to know how feasible traffic restrictions could be in other cities around the world, but as urban planners look to curb traffic for other reasons, like congestion or air quality, Worden says that cutting carbon emissions is a powerful added benefit.