Where can you buy carbon offsets?

Carbon offsets can help to lessen your impact on the environment. As far as environmental actions go, they're relatively easy to enact – no matter where you live, you can purchase them from brokers online. Some of the more popular brokers of carbon offsets in the U.S. today are NativeEnergy, terrapass, and the Climate Trust.

In addition, it's increasingly common for retail companies to offer the option to purchase carbon offsets from a recommended provider, especially if what you're purchasing from them will directly result in more greenhouse gas emissions. For example, travel often results in comparatively high greenhouse gas emissions. Many airlines, rental car companies, and hotels offer the option for you to buy carbon offsets along with your reservation so that you can offset emissions from your use or trip.

If you're looking to be "green," purchasing carbon offsets isn't just a solution to decrease your personal greenhouse gas emissions – you can buy them to offset emissions whether or not you're trying to shrink your carbon footprint.

That's not to say you should blindly purchase carbon offsets anytime it's being offered as an option. There are do's and don'ts of purchasing these offsets that you want to keep in mind if you're in the market. Many companies offer carbon offsets, either from a third-party provider or for projects that their companies play a role in developing. Do your research to ensure that your investment is having the biggest impact possible on the planet as a consumer.

When you buy a carbon offset, you're often provided some sort of choice about the type of project (renewable energy, energy efficiency, methane capture, tree planting, etc.), along with details regarding the project.

One factor to consider is whether or not you want to purchase local carbon offsets or offsets for national or international projects. If you purchase local offsets, you can support projects close to your home, which has the added benefit of not only combating greenhouse gas emissions but also contributing to your local economy.

National and international offsets can also support their own local communities. Investing in national/international projects versus local also means that your money can go where it's most needed (if you want to invest in a project offset directed towards protecting rainforests but live in a city, buying offsets for a non-local project is probably going to be the direction to go in).

Overall, local and national/international offsets offer the same large-scale benefit in terms of environmental impact. The net effect of greenhouse gases in the global atmosphere is what's important – a tonne of carbon dioxide offset in China will have the same overall impact on the earth as the same amount of carbon offset in Boston, Massachusetts.

Some companies that offer carbon offsets are not transparent about the projects they are funding or the actual impact they will have on the environment. Not all offset projects are created equal, and if your aim in purchasing an offset is to have the greatest environmental and social impact possible, you want to make sure you're investing in a reputable organization.

What makes an offset (or a company that sells them) reputable? There are a few major questions that you should seek answers to before you invest in a carbon offset project.

Does the project have longevity and permanence?

If you're looking to have the greatest impact over time, you want to ensure that the project will continue for years to come. For example, one type of offsetting project that sometimes draws criticism is tree planting. Planting additional trees can lead to more sequestered carbon and decrease the overall concentration of greenhouse gases in the atmosphere. However, there isn't a guarantee when it comes to the health of the trees planted or their longevity – the initial action of planting trees doesn't help much if those trees don't grow and continue to capture carbon over time.

Is this project considered "additional" or not?

When a project is referred to as "additional," it's an indication that the primary purpose is to decrease greenhouse gas emissions rather than an action that is going to be done regardless of your investment. Another way to think of this: is your contribution preventing further GHGs from reaching the atmosphere, or is it funding an existing project or one that was going to happen anyway?

Is there any potential "leakage" associated with the project? 

It doesn't hurt to invest in any type of project that has the potential to decrease greenhouse gas emissions, but does the project you're looking to invest in have the possibility of increasing greenhouse gas emissions nearby? This is a common concern for forest preservation projects – if you invest to protect a portion of the Amazon, will logging companies simply move operations farther south and cut down a different part of the rainforest?

How is the carbon offset going to be measured? 

Is this measurement of the number of carbon tonnes going to be accurate and reported? If you're buying carbon offsets to combat a specific amount of emissions in the atmosphere, you want to ensure this is tracked for the project's scope.

Many third parties have developed certification programs for carbon offsets to provide transparency and verification of reputable offset projects. Among the most well-known reputable certifications and organizations recommending carbon offset projects are:

• Green-e Climate Protocol for Renewable Energy endorses specific certification programs like the Gold Standard, Verified Carbon Standard, and Climate Action Reserve and presents itself as consumer-focused to protect both buyers and sellers in the offset market.

• Gold Standard is a nonprofit that works with renewable energy and energy efficiency projects related to sustainable development.

• Verified Carbon Standard is a nonprofit organization that certifies additional projects outside solely renewable energy and energy efficiency (forestry, etc.)

• Climate Action Reserve certifies projects that are specifically in North America. If you're looking to invest in a more "local" carbon offset project, Climate Action Reserve is a good place to start.

Projects that meet the guidelines set by these organizations have to go through an application and verification process, which certifies that they meet basic criteria and ensures their authenticity and impact.