Stories of questionable "carbon offset" sales schemes keep blowing in. Here are articles on this hot global warming industry in The Sun, The Washington Post, The Kansas City Star and some discussion of the problems on businessGreenblog.

It's beginning to sound like multiple sightings of the emperor's lack of clothing. Perhaps one problem lies in the ambiguity of the term "carbon offset" itself -- which smells of an Orwellian pollution of the English language.

After all, when you buy "carbon offsets" that doesn't necessarily mean you're paying for a reduction in carbon dioxide pollution. You could be sending payments to a utility company that might (or might not) use your money to help build a wind turbine that might eventually generate a small amount of electricity -- as it continues to build more coal-fired power plants that spew even more greenhouse gases.

But that's the magic of the word "offset" -- it doesn't promise a reduction. It doesn't really promise anything. You are "setting" something "off" somewhere -- perhaps only setting off a migrane in customers trying to figure out where the hell their money is going.

As I reported in The Sun, a growing number of firms -- including the nonprofit group Carbonfund in Silver Spring, Md. -- are selling what is essentially an invisible balm to soothe people's feelings of guilt over global warming.

If you feel bad about the carbon dioxide generated by your driving and flying, you can type your credit card number in to the website of Carbonfund and for $99 get a "total carbon offset" for a whole year -- meaning a bumper sticker proclaiming that you are fighting global warming. In theory, that money could go to plant trees (which absorb carbon dioxide as they grow). But some critics argue that the real cause of deforestation is government land-use policies and development -- which won't be affected by a few hundred bucks donated to plant saplings.

Or the money you donate could go to buy "renewable energy certificates" (another wonderfully opaque term). These are essentially subsidies sent to utilies after they build wind turnbines to make the wind industry in general more profitable. But that doesn't mean the money is going to build new wind turbines. It could be going to build profit.

Or as David Fahrenthold and Steven Mufson of The Washington Post wrote in their Aug. 16 story: "The offset is among the most unusual of commodities. It's substance is intangible, the absence of something. Some pollution would have existed, somewhere, sometime, the seller says, and now it won't."

Businessgreenblog writes of the industry: "Several experts claim there are instances where the same carbon credit - representing a tonne of saved carbon - has been sold several times over. There are also concerns that calculations used to work out if a tonne of carbon has genuinely been saved are unreliable, with some critics suggesting credits are being sold on the basis of projects that may have gone ahead anyway."

Concerned? Here is a consumer's guide to buying carbon offsets.

Some carbon offset companies pay a fee to be able to display a "Green E" guarantee on their website -- which supposedly means that an independent firm has verified the offsets. But the Green E program told The Sun that they routinely let their clients display this logo for up to a year before they do any checking of anything -- and then it's only a paper check. Oh, and they don't actually certify carbon offsets -- just alternative energy projects. So the Green E is essentially a big green question mark.

A simple solution: stop calling them "carbon offsets." Instead, if you want to raise donations to plant trees, market yourself as a tree planting organization. If you want to build wind turbines, call yourself a wind power firm. That way, there would be no linguistic ambiguity -- and people could hold you responsible for doing exactly what you say you're going to do with their money.

Nobody would be left twisting in the wind.