A carbon neutral lifestyle, business, or organization is an attainable goal. It can mostly be achieved through energy conservation and use of alternative fuels. But in these transitional times, before things like biofuels and wind power become widespread in the economy, there are instances when you just can’t avoid the use of fossil fuels. This is especially true for transportation over long distances, be it by plane, train, or automobile. To take those stray emissions out of the air, you can offset them.

Carbon offsetting involves undertaking an activity that ultimately takes carbon out of the air. Some projects involve donating money to startup alternative energy companies in exchange for emissions credits, considered to be a long-term investment in zero-carbon power or fuel production. Other projects, such as reforestation projects or just planting a few more trees, enhance the natural processes that trap carbon dioxide into solid form, thereby directly taking it out of the atmosphere. If you are responsible for more pounds of carbon than you can handle by yourself, there are companies that can help by doing the work for you.

But because the benefits of carbon offsetting are limited and somewhat uncertain, they should be used only to top off a comprehensive program of emissions reduction and energy efficiency, not as an alternative to them. There are also some companies that promise far more than they deliver, and even a few with questionable practices such as counting monocropped tree plantations, ultimately intended for industrial use, toward the emissions offset. Your best bet is to try to offset your own emissions with tree planting, focusing most of your efforts on energy conservation. If you can’t, then research the companies you are thinking about using to ensure that their business practices are as impeccable as they advertise. Carbonfund.org, Native Energy, and Terrapass are a few examples of organizations that the Will Steger Foundation has found to be committed partners in achieving a zero-carbon world.