Here's How You Can Reduce Your Carbon Footprint

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WATCH Reduce your Carbon Footprint

Do you know your carbon footprint? Probably not, unless you are incredibly well informed about the many factors that determine how much impact you will leave on this planet during your journey through life. And now researchers at the University of California, Berkeley, have added a new level of complexity to the problem.

One size does not fit all. What works for Uncle Billy in Plaintown, Nebraska, probably won't work for you.

Lifestyle, family income and even age all contribute to a wide variation in the size of an individual's carbon footprint.

Researchers Christopher Jones and Daniel Kammen of Berkeley's Energy and Resources Group have tried to make it easier for a family or an individual to come up with a reasonable estimate of how many tons of carbon they contribute each year.

"Everyone has a unique carbon footprint," said Jones, lead author of the study published in the journal Environmental Science & Technology. The researchers studied all 50 states and 28 metropolitan areas to determine which strategies would work best in each of those areas.

The bottom line: it is possible to reduce a carbon footprint and save money at the same time. It may not be a huge difference, but multiplied by potentially millions of concerned citizens it could add up to a major impact.

Berkeley Scientists Create Online Carbon Calculator

Jones and Kammen have created a "carbon calculator" that is available to anyone at The calculator asks the visitor a few questions and determines which actions would likely lead to the greatest reduction in the size of the footprint.

It's not a perfect solution, because conditions vary so much across the country, even within individual cities and states. But the researchers say it's easy to use and should be helpful to nearly anyone. They picked two locations to illustrate the considerable differences from one region to another.

A couple living in San Francisco and earning $90,000 a year leave a carbon footprint dominated by emissions from motor vehicles and air travel. Their household energy consumption is about half the national average because of a moderate climate. They could reduce their footprint the most by trading their car for a hybrid and reducing their air travel. That would also save them about $2,100 a year, and maybe even improve their social status by choosing a vehicle based on its fuel consumption.

Carbon Footprints Vary Across the Country

It's a very different story for a household of five living in St. Louis earning $45,000 a year. Their footprint is dominated by emissions from electricity because of the need to heat and cool the house throughout the year. They could reduce their footprint by raising the thermostat in the summer and lowering it in the winter just a few degrees, possibly saving $1,400 a year while reducing their footprint.

Here are some other variations across the country:

San Francisco and San Diego have the lowest household energy emissions, but very high transportation footprints. Minneapolis, which has the lowest household size also has the largest overall carbon footprint, a bit of a surprise. New York, Boston and Baltimore have relatively high household incomes, and low overall carbon footprints. Changing diet (less red meat and dairy products) saved the most money, about $850 a year. Driving a more fuel-efficient car had the greatest impact on the footprint, even if the gain is only five miles per gallon.

The researchers note that if a person can't afford a new economical car, he or she could achieve a similar result by driving slower and less aggressively. That could also save a life.

Footprint Calculators Viewed as Simplistic by Some

The Berkeley website is the latest in a long line of "footprint calculators," many of which have come under attack by researchers who view them as simplistic -- and often incorrect -- answers to a very complex problem. To really know your footprint, you need to know just about everything that is required to sustain your life: How much damage was done all along the way in building that economy car, or getting that steak to the dinner table, or producing the electricity to power your coffee pot.

That has become a somewhat heated issue in the production of biofuels. A Duke University study found that if you want to reduce greenhouse gas emissions, don't plant corn for ethanol production. Leave the land vacant instead. Growing, harvesting and converting corn can be a messy business. That, in turn, has come under attack by other researchers, including Michigan State University's Bruce Dale, who argues that proper crop management could still make corn-ethanol production a good deal.

Carbon Footprint Not a New Phenomenon

It's a very complex issue with many poorly understood variables, as evidenced by the lack of consensus among experts.

Incidentally, carbon footprint may be a relatively new term, but it's not a new phenomenon.

Ohio University scientists stumbled upon evidence that native Americans left a carbon footprint more than 2,000 years ago. Working with scientists at several other institutions, the Ohio team was studying historic drought cycles in North America using carbon isotopes in stalagmites. To their surprise, the carbon record contained evidence of a major change in the local ecosystem at around 100 B.C.

That coincided with archeological evidence found in a nearby cave of a Native American community there 2,000 years ago. The scientists believe the Indians altered the local ecosystem by clearing and burning forests, probably to increase production of nuts and fruits.

So, long before anyone knew that greenhouse gases were altering the global climate, humans were already leaving a carbon footprint.