Not if you ask Gavin Newson, mayor of San Francisco, who helped bring carbon offset kiosks to that city’s airport. Last week, SFO became the first airport in the nation to offer air travelers a way to offset the greenhouse gases their flight will add to the Earth’s atmosphere.

A buildup of greenhouse gases, including carbon dioxide (CO2), is known to cause global warming.

Here’s how the three Climate Passport kiosks at SFO work:

• you enter information about your trip on a touch screen
• the computer calculates how many pounds of carbon dioxide (and other greenhouse gases) your trip will produce
• it suggests how much you’d need to donate to local projects aimed at reducing greenhouse gases in order to “offset” the damage your trip will inflict on the environment
• the money goes to renewable energy, energy efficiency, and reforestation projects, like Garcia River Forest and Dogpatch Biofuels
• The kiosks are after the security checkpoints on both sides of the International Terminal, and in Terminal 3.

How much does a clean conscious cost? According to the computer, a trip from Vancouver to SFO and back, for instance, would produce 1,186 pounds of carbon dioxide, which could be offset with a contribution of $7.26, while a one-way trip from SFO to Boston would produce 1,999 pounds of carbon dioxide, which could be offset for $12.24.

Naysayers: Carbon offsetting is a complex issue, and the naysayers are already out in force, with hundreds commenting on Sfgate.com’s article on the kiosks, most of the comments were along these lines:

• There’s a sucker born every minute.
• Fool + money = parted
• BUY THIS AND YOU ARE AS DUMB AS A STONE!!
• PT Barnum would have been proud.

Funny, yes,  but I think this one is actually more accurate:

“I betcha a lot more people have an idea of how much carbon their flights are producing after having read this story than before. Fighting global warming is a hearts and minds struggle.”

Want to know more about carbon offsets and what air travel does to the environment?

• Learn more about the carbon footprint of your flight.
• Wikipedia on how to become carbon neutral.
• Budget Travel defines carbon offsets and discusses whether or not they work.
• Ed Hasbrouck, round-the-world travel guru and blogger, has a great post on this year’s conference on aviation and the environment in Geneva.  He writes of struggling with the recognition that “all travel, and especially long-haul air travel, has adverse ecological consequences” while still believing that “long-haul travel, even by air, can in particular cases have a net positive effect on the world, mainly through the secondary effects of the permanent changes it can bring about in our worldview, which result in changes in how we go on with our lives.”