Roadtrippers Karin Catchpole and Eric Mohl are buying carbon offsets to reduce the impact of their Trans-Americas Journey.

The money they use to purchase offsets is spent on carbon-reducing projects such as renewable energy, energy efficiency and reforestation initiatives.

Although actual greenhouse gas emission reductions should be the primary goal, carbon offsets are seen as an important component of most GHG reduction strategies.

Catchpole and Mohl are using the offset projects available though the Chicago Climate Exchange ("CCX") to reduce their carbon footprint.

While only CCX members can buy offsets directly from the exchange, roadtrippers can use third party organizations like Carbonfund.org, Terrapass.com and Liveneutral.org to purchase offsets on their behalf.

Each of these organizations' websites also have carbon calculators that allow roadtrippers to tally up their emissions based on distance traveled and vehicle used.

According to a November 2007 article in the New York Times, the number of offsets sold by TerraPass, Carbonfund.org and other online retailers is increasing significantly on a year to year basis.