As the holiday season rolls around, many families across America are thinking of vacation travel—a drive back to the family home, a train ride out of the city, or a flight to warmer climes. But while green vacations have become de rigeur among the eco-conscious, surprisingly few vacation packages take into account the impact transportation will have on a vacation's overall carbon footprint. In fact, until now, no hard, analytic guide has been released to provide consumers with the facts they need to best mitigate the emissions impact of their next vacation.

Fortunately, for consumers and green travel planning agencies alike, the Union of Concerned Scientists has released Getting There Greener, a first-of-its-kind green travel guide designed to help families, couples and solo travelers determine the cleanest way to to move about the country. Weighing in at a hefty 67 pages, the report is straightforward and surprisingly readable, distilling its scientific methodology into easy-to-comprehend charts and tables. A single-page quick reference chart [pdf] has also been produced, perfect for keeping around the office to plan business trips.

While many Americans go to great lengths to limit emissions created in their daily commute, Jim Kliesch, a UCS senior engineer who helped author the guide, notes in the UCS press release, "Vacation travel can generate a surprising amount of global warming pollution." Indeed, in the report's opening pages, it reveals how a Disneyworld vacation for a family of four can in a single weekend easily outstrip the parents' commuting emissions for the entire year.

Aside from basic travel tips and advice, the guide also fills an important factual niche. Before its release, uncertainty reigned over what methods of transportation offer travelers the smallest environmental impact. Claims still range wildly, with some saying rail is the best, and motor coaches are the worst, and others citing trains as the most harmful. But the UCS study, planned and designed from the outset to directly compare the carbon impact of various modes of transport, shows all but irrefutably that motorcoaches—yes, tour buses—are, in most cases, the most carbon-friendly way to get around the United States.

Rather than cling to that simple, rule, though Getting There Greener digs further, providing an array of tables and charts that allows travelers to carefully asses their own impacts for each leg of their journey, and calculate a reliable estimate for any combination of multimodal journeys. While the data is largely specific to the US, many carbon saving tips (e.g., relying on better fuel economy cars, choosing direct flights) will apply elsewhere as well.

Flickr photo courtesy of TeamYeti