Erik Daehler loves to travel. But every time he gets on an airplane, he knows his carbon footprint gets bigger. "It's had a horrible imprint on my carbon footprint," admits the 30-year-old physicist and aerospace engineer from Southern California.
What, might you ask, is a carbon footprint?
A carbon footprint is the measure of the amount of carbon dioxide -- the major man-made global warming greenhouse gas -- that goes into the atmosphere as you go about your daily life. Almost everything you do affects it: turning on a coffee maker, driving a car, buying food -- and in Daehler's case -- taking a ride on a passenger jet.
Air travel accounts for about 3.5 percent of the human contribution to global warming, according to the Intergovernmental Panel on Climate Change. The good news is you can offset -- if not eliminate -- your carbon footprint by making choices that can even save you money.
"What do I give up to do that air travel?" asked Daehler. "Well, maybe I won't use the heater as much this winter."
Making these kinds of choices has become a growing trend among people who want to reduce the size of their carbon footprints. At the same time, they must grapple with the question of whether their actions really make any difference.
Many people have employed a number of low-tech ideas that all play a small part in reducing their footprints: reusing canvas shopping bags, taking shorter showers, and walking or riding a bicycle for short trips around town.
Increasingly, many have turned to Web sites that offer carbon calculators, which add up how much carbon dioxide gas their lifestyle puts into the atmosphere. You increase your carbon footprint by driving a sport utility vehicle, for example, or reduce it by driving a hybrid.
Experts say one of the first things you can do to reduce your carbon footprint is to get smart about energy efficiency.
Many people may not realize that electricity production -- derived from coal-burning power plants -- is one of the biggest sources of carbon emissions. Seventy percent of all U.S. electricity is produced as a result of burning fossil fuels, according to the Union of Concerned Scientists.
"Efficiency is the least expensive way to cut down on your carbon footprint," said John Steelman, director of the climate program at the Natural Resources Defense Council.
On average, every American is responsible for about 22 tons of carbon dioxide emissions every year, according to statistics compiled by the United Nations. That is far above the world average of 6 tons per capita. Thus, experts say there's lots of ways to reduce your carbon footprint inexpensively by taking some simple steps at home.
How? Web sites like stopglobalwarming.org have carbon calculators that offer dozens of suggestions for cutting emissions around your house. For example, the site says that moving a thermostat down two degrees in winter and up two degrees in summer will save 2,000 pounds of carbon dioxide and $98 a year.
If every household in America replaced just three bulbs with energy-efficient fluorescent bulbs, we would all save $60 a year and collectively keep a trillion pounds of CO2 out of the atmosphere, according to the site.
Daehler has replaced all his light bulbs with energy-efficient bulbs and has watched his electricity bill drop 12 percent. He said many people often don't realize that electronic devices like VCRs and stereos that stay plugged in all day are also drawing power, even if they are turned off.
These items, which include cell phone and iPod chargers, draw what is known as a phantom load. "They call them vampires," said Daehler, who makes sure to unplug his chargers when he's not using them. "They constantly draw about a watt of energy," he said. "And if you have 10 of those in your house, always plugged in, that's 240 watt hours a day. That's simple. Unplug it."
Experts say another simple step is weatherizing your home. It can save hundreds of dollars and about 1,000 pounds of CO2 annually.
"There's so much you can do to stop bleeding wasted energy," Steelman said. He suggests calling your local utility provider to ask for a free energy audit that can point out where a home may be inefficient. "If a house still has single-pane windows, for example, it's almost like having a hole in the wall," said Steelman.
Stopglobalwarming.org says that installing double-pane windows can save 10,000 pounds of CO2 a year. But the upfront cost to install double-pane windows -- often thousands of dollars -- can be expensive. But some cities and power companies offer ways to offset those costs.
Tony Napolillo, a marketing manager with a green energy company in Texas, makes reducing his carbon footprint a part of everyday life. He credits the city of Austin with providing incentives and rebates on, for example, air conditioners and landscaping -- things that helped him transform his home into a model of energy efficiency.
"The programmable thermostat and the compact fluorescent light bulbs were all provided by the city," he said. "It's made a huge difference on what my house uses and loses."
Kym Trippsmith, a writer for a financial Web site, would like to go a step further and install a solar panel system for her California home. "But it's $40,000," she said, too expensive an upfront cost to install all at once. But if she could make it happen, she said her footprint would shrink and her wallet would grow. "I hope to save $6,000 a year," she said. "Within eight years, that system would completely pay for itself."
Practically everything we buy has a carbon cost associated with it that consists of things like transportation costs and the amount of electricity that goes into manufacturing a product or packaging.
Even natural foods often have a carbon impact.
For example, fruits and vegetables are transported on trucks that drive an average of 1,500 miles from field to supermarket, according to a 2001 U.S. Department of Agriculture study.
So Daehler buys fruits and vegetables only from local farmers' markets.
"The negative side is that you can't buy some things in season," he said. "I can't get strawberries 100 percent of the year. But that's OK. I'd much rather have strawberries that are fresh and locally grown, since that reduces the total transportation cost."
Personal transportation choices can also shrink a carbon footprint. Many people choose to walk, ride a bicycle or a scooter on short trips around town. Some cut their emissions by shopping at stores -- or even by taking jobs -- that are closer to home.
Another choice requires giving up the gas-guzzling car you have now for something more efficient.
"People don't want to hear that," said Napolillo. "They want to drive what they want to drive and they don't want someone to tell them what to do. But eventually it's going to catch up with us. Or maybe not us, but it's going to catch up with our kids or our grandkids or further down."
If you can afford a hybrid, stopglobalwarming.org says you can save 16,000 pounds of CO2 and $3,750 a year. You don't even have to give up your SUV.
"SUVs out there now have hybrid options," said Steelman. "With a little bit of research, people can have a big impact on what they buy without sacrificing any aspect of their comfort or what they like to drive. But it just takes a little more effort upfront."
In Daeler's case, carpooling didn't just help reduce his carbon footprint by 1,590 pounds a year. For a while, he commuted with his boss. When the boss moved on to another job, Daehler was promoted to fill the slot.
"It's very beneficial to your career if you're commuting with your boss," Daehler said.
So you've improved energy efficiency at home, when you drive, and when you shop. What else can you do to reduce your carbon footprint?
Many people are now asking their utility companies for "green power" options in which they pay a little extra for power that is generated by cleaner wind or solar technology. If your utility doesn't offer a green option, a growing number of private companies offer "green tags" that help you offset your carbon emissions from electricity.
"The average residential utility usage in the United States is about 1,000 kilowatt hours, or one megawatt hour a month," said Tom Starrs at Bonneville Environmental Foundation in Portland, Ore.
Bonneville offers green tags that cost $20 to $24 a month, depending on what combination of clean power you choose. The clean power won't actually be delivered to your home, but the money goes toward investing in wind or solar technology that, proponents said, reduces the electricity that has to be generated by coal-burning power plants.
"When you offset your usage through a green tag purchase, you're preventing about 1,400 pounds of CO2 and other greenhouse gas emissions a month, or about 16,800 pounds a year," said Starrs.
Napolillo said the green power option in Austin has actually become cheaper than regular power, which, in Austin, is generated by higher-priced natural gas. "It's actually exceeding the cost of green energy," Napolillo said.
The real question, of course, is whether individual efforts to reduce carbon footprints will have a positive effect on cutting greenhouse gases, or be worth the sacrifice. Some are not optimistic.
"I drive a Prius. I have a garden," said Trippsmith. "We have a smaller footprint than most. But it's a drop in the bucket. If everybody drove a hybrid in America, we might have a chance."
Erik Daehler said sacrifice is a small part of reducing your carbon footprint, but it's worth it.
"You do have to sacrifice," said Daehler. "I think a lot of people are going to have to soon assess themselves and figure out that what they give up now may allow their kids to have it, or their kids' kids to have it. It's sort of a selfish relationship we have with the environment right now."
Daehler said that his individual contribution to reducing greenhouse gas pollution is small, but has begun to see anecdotal evidence that people are changing their ways.
"Is one person making a little bit of an impact when there's five billion people in the world? It seems insignificant," he said. "But what you find is, the more people you touch, and give the word to and talk to, the more it moves.
"When I first bought my first hybrid three years ago," Daehler adds, "no one I knew had one. And within six months, I had four or five friends sell their trucks and SUVs and purchase hybrids. Now I can name a dozen friends who have hybrids. So you start to see a cumulative effect."
But even reducing your footprint to zero and living a so-called carbon neutral life may not be enough, said the NRDC's Steelman.
"You can take yourself out of the equation," he said. "But that doesn't change that coal plant into a clean power generation plant. So, in addition to making changes in your own life, it's holding politicians accountable and raising your political voice to solve the problem."
But Tony Napolillo said he won't wait for politicians to act.
"Everybody has to realize they have personal responsibility," he said. "They can't just wait for the government or the corporate world to do something about it. If everybody could strive to be carbon neutral, this would be a greater world."