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."