Phones, Facebook, and the environment: a group of kids is using technology to reduce their carbon output.

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Cell phones and Facebook can do more than send messages--they can also help teens keep track of their impact on the environment. Using cell phones equipped with Global Positioning Systems (GPS), 25 students at the Urban School in San Francisco tracked their modes of transportation and the resulting emissions of carbon dioxide, a greenhouse gas that contributes to global warming.

Whenever students got in a car, biked, took the bus, or walked somewhere, the Center for Embedded Networked Sensing at the University of California, Los Angeles, would collect information every 30 seconds from the traveling teenagers. Using special software, the center could determine the students' mode of transport and calculate how much pollution they released into the atmosphere as a result of their trip. When the students arrived at their destination, they could post the data on their Facebook pages.

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The collected information allowed the students to see how their choices contributed to their carbon footprint, or the quantity of greenhouse gases like carbon dioxide produced by their everyday actions.

CARBON COUNTS

Powered transportation accounts for about one third of greenhouse gas emissions in the U.S. When we burn fossil fuels, like the oil and gasoline used to power planes, cars, and buses, carbon dioxide is released into the air.

"This carbon dioxide has been building up in the atmosphere--increasing by more than 30 percent because of human activities," says Gavin Schmidt, a climatologist at the NASA Goddard Institute for Space Studies in New York.

Those changes strengthen the greenhouse effect, the process by which heat from the sun is trapped by certain gases in the atmosphere, making our planet livable. According to most scientists, though, too high a concentration of those gases can cause global warming, leading to changes in Earth's temperature, melting ice caps, and rising sea levels.

By knowing their carbon footprint, the students could work to shrink it in the future. They could even figure out ways to have smaller carbon footprints than their friends. "You can think about [climate change], and you can want to do something about [it], but to make a conscious decision to take another form of transportation instead of driving a car is where the real change lies," says Julia Evans, who carried one of the phones last year as a senior. Schmidt agrees. "Keeping track of your emissions, and hopefully reducing them in concert with everyone else, is a positive step toward reducing the scale of future problems," he says.

COOLER SOLUTIONS

One way to reduce the amount of carbon dioxide emitted into the atmosphere is to choose forms of transportation that release less of the gas.

"Using bikes and mass transit, and walking instead of relying on a vehicle is often a realistic, environmentally friendly, and healthy option for many trips that people take," says Aaron Huertas from the non-profit group Union of Concerned Scientists.

The Go Green Foundation that worked with the students at the Urban School in San Francisco hopes to spotlight those choices. It is planning to expand the project so that 75 kids from three different high schools can track their transportation emissions. The schools will compete to reduce their collective emissions, including those from transportation, by a total of 525,000 pounds of carbon dioxide. That is the equivalent of taking 44 cars off the road for a year.

It's important for teenagers to see how they contribute to global warming, according to Huertas. "Students will inherit the climate future we're locking in today," he says.

web extra

Calculate your family's carbon footprint and more at Scholastic's Act Green site: www.scholastic.com/scienceworld

DID YOU KNOW?

* The average American generates 20 tons of carbon dioxide per year, which is well above the world average of 4 tons of carbon dioxide per person per year.

CRITICAL THINKING:

* The students featured in the article used their cell phones to track their C[O.sub.2] emissions and then posted their results on Facebook. Would you want to be part of a similar program at your school? Why or why not?

CROSS-CURRICULAR CONNECTIONS:

ART: Check out the suggestions of ways to reduce your carbon footprint in this article: www.guardian.co.uk/environment/2009/sep/01/how-to-reduce-emissions-10-10 Then, pick one of the ideas and make an informative poster.

RESOURCE Find this link at www.scholastic.com/scienceworld

* Check out the Environmental Protection Agency's Climate Change Kids Site that's full of information, activities, and lesson plans: http://epa.gov/climatechange/kids.

DIRECTIONS: Answer the following questions in complete sentences.

1. What tools did the students at Urban School use to track their carbon dioxide emissions?

2. What lifestyle changes does the article mention that can reduce your carbon footprint?

3. How is the Go Green Foundation planning to expand its program?

1. The students at Urban School used cell phones equipped with GPS technology to track their carbon emissions as they traveled, They then uploaded their data to Facebook.

2. Some lifestyle changes that you can make to reduce your carbon footprint are: using bikes, mass transit, and walking instead of relying on a car.

3. The Go Green Foundation is planning on expanding its program from 25 kids in one school to 75 kids in three different high schools. Then the schools can compete to reduce their collective emissions.