22 April 2007

Carbon Offsets -- Can They Help?

photo of jet airliner from a NASA site

Carbon Offsets May or May Not Offset Any Carbon

When you pay for a "carbon offset" the money goes to a company or non-profit project (maybe through a broker or other agent, who takes a cut). That company or project is doing something that sequesters carbon or generates low-carbon energy. The money it gets by selling offsets helps the economics of the project.

People often buy offsets because it is easier or cheaper for them to do so than to actually reduce the carbon their activities emit. For example, you may really want to take a plane trip. When that plane flys it emits CO2. (Of course, it would emit essentially the same amount of CO2 if you stayed home.) You can "offset" the carbon emissions your trip caused by arranging, for example, to reduce greenhouse gas emissions somewhere else.

The key to getting carbon offsets to make sense is: Whatever you buy when you buy the carbon offset must actually result in the absorption of the amount of CO2 you produce, or the substitution of energy made without emitting CO2 for carbon-intensive energy, or by capture of emissions that would have been released if you hadn't chipped in. But what if:
  • The trees would have been planted anyway, even if you had not bought the offset.

  • The trees are to be planted in a northern clime where they will absorb more winter sunlight than the snow they cover, thus actually increasing global warming in spite of the carbon they absorb? (See this study and these comments.)

  • The trees are planted in what was a tropical peat bog or forest, and more CO2 is emitted when planting them than they will ever absorb? (This study)

  • The electricity generated by the wind-power project you supported will not substitute for carbon-based power, but just add to it, driving down the price of electricity and encouraging consumption?


There are certification schemes to assure that at least some offsets don't have these problems. The key is that the projects provide "additionality". That means that they offer additional carbon reduction that wouldn't have been achieved without your purchase of an offset. Here is the complicated method used to determine additionality.

In general, if you want your carbon offsets to really reduce CO2 emissions, they should comply with the criteria established by The Gold Standard, which specifically excludes tree-planting and similar schemes, or other strict certification programs. This paper by Friends of the Earth, Greenpeace and WWF explains why.

How do you find an offset that will really reduce global carbon in a way that will make up for the greenhouse gasses you continue to produce? The Environmental Defense "Fight Global Warming" page lists some offset projects they have vetted.

But wouldn't it be better for you to actually reduce the amount of carbon your activities emit? At worst, carbon offsets provide a way for wealthy people to ease their consciences when they pursue carbon-intensive activities. At best, they compensate for those activities, so we come out even. The only way to come out ahead (that is, to actually reduce your carbon emissions) is to change your lifestyle.


Carbon offsets can help, but only if you do your homework. And they can't do the whole job.

Some questions:

  • Should new nuclear power plants be able to sell carbon offsets?

  • Currently, British Airways offers to arrange carbon offsets for its passengers (the passengers pay for them). Why doesn't it simply buy enough offsets to make the flight carbon neutral and add the cost to the price of the tickets? (Answer obvious: people would fly cheaper, carbon-positive flights with competitors.)

  • Could you make money setting up a gas station that bought carbon offsets to make all the fuel it sold carbon neutral, and added their cost to the cost of the gas? How much more would the gas cost? Would anybody buy it? (Business plan idea here -- maybe you could enter the California CleanTech Open and win $100,000.)

  • What if the legislature mandated that all gas stations do this, so that the cost of fuel would reflect its true environmental impact?

These posts are thoughts that have occurred to us here at GCF Associates and Global Climate Fund. Feel free to contact us if you have any questions or ideas for future posts.

Here are some useful links:


David Suzuki Foundation has some good links

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