Name which of these spring break staples doesn't fit:

A) Cancun

B) Caribbean cruises

C) Carbon offsets

Letter C, right? When most college students think about spring break, they likely envision tropical climates, cold drinks and swaths of other young spring breakers just like them. And carbon offsets? Not so much.

But environmentally conscious travel companies such as REI Adventures and Adventure Collection are looking to change that, mixing in a new green twist.

Even if you can't afford a vacation package, college students can cut back with little effort. Choose local restaurants and bars over franchise eateries. Ask for locally brewed beers. If you're feeling especially green (and have the cash), buy carbon offsets to reduce your carbon footprint. Stay in more environmentally friendly digs. Avoiding buying souvenirs derived from protected or endangered animals.

But first, how you're getting to your S.B. '09 destination. While flying may be the quickest and most efficient way to travel, it's also one of the least environmentally friendly, as planes emit significant amounts of greenhouse gases. For instance, my own round trip spring break flight from Detroit to Fort Lauderdale last week alone emitted 738 pounds of CO2. (Calculate CO2 emissions for your own flights here.)

If you have no choice but to fly (driving to Puerto Vallarta from Boston isn't really an option, now is it?) but want to do something about your flight's environmental impact, then buying carbon offsets isn't a bad way to go.

Carbon offsets are credits individuals or businesses can buy that neutralize their carbon output: You pay a company like Carbon Fund, who will help you calculate your carbon footprint and suggest how much you should pay, and then that company uses your money to support renewable energy, sustainability and reforestation projects.

Now, carbon offsets are hardly an ideal solution—that would be cutting emissions to start with—but they're better than nothing and a worthwhile cause if you can't avoid that spring break flight.

Otherwise, if you can drive, do it. Or even better, bike. Or best of all, walk. Consider taking a staycation—a vacation where you don't have to leave home.

Odds are there are a few prime vacation spots right under your nose that you have yet to discover but would make great spring break destinations. And not only do staycations cut your carbon footprint, but they're easily done on a tight budget, too.

Now, if you're feeling particularly inspired to not only cut emissions and give back to a community, options like Alternative Spring Break and Habitat for Humanity's Collegiate Challenge send students and young people out into communities throughout the country as volunteers, helping to plant trees and gardens or build homes in urban and rural locations. The costs of such trips are dirt cheap—$150 for the United Way's ASB program and $15 for the Collegiate Challenge—and you actually contribute to the environment instead of only minimizing your impact on it.

For some, it may be too late now to overhaul your plans—but that doesn't mean you can't purchase a few carbon offsets, eat and drink local wherever you're heading and walk instead of take cabs between, say, the hotel and the beach. (As long as it's safe, of course.) So add some green to your sun and sand.