What does 'carbon offset' mean?

The idea

Carbon is an element, so it is not created or destroyed. No carbon enters or leaves earth. Therefore, the amount of carbon on earth never changes. It exists in several forms:

• carbon dioxide, a greenhouse gas
• inside living things - people, animals, trees, plankton, etc.
• buried underground (in land or sea) in the form of fossil fuels (coal, oil and natural gas)

When we burn fossil fuels, the carbon in them is turned to carbon dioxide and released into the air, where it causes global warming.

However, life is largely made of carbon; anything alive has got carbon from somewhere. Plants take carbon dioxide from the air and turn it into the organic chemicals they need to survive and grow (we say they "fix carbon"). In this way carbon is moved from the air to a "carbon sink", which is a good thing.

Suppose I cause one kilogram of carbon to be released into the air (say, by driving to work every day). Now suppose I plant a tree which will eventually grow so big that it contains one kilogram of carbon. Then the tree would have absorbed the carbon from the air, and my overall contribution to global warming would be zero.

But instead of planting trees in my own back garden, I can pay a company to plant trees. These companies plant lots of trees, and for every kilogram of carbon they offset they issue a certificate. I can buy one of these certificates, which effectively means I'm planting trees (by paying the company that plants them).

(There's another idea, known as "Carbon Capture and Storage". This hasn't (yet) been made to work. The idea is to freeze carbon dioxide and store it at the bottom of the sea, or pump it deep below the ground where it won't leak out.)

Problems

There are objections to carbon offsetting. In my opinion, fossil fuels are a much better carbon sink than trees, because they are out of the way. Trees, on the other hand, can be cut down to make way for farmland or towns. We can take land from farms and plant it with trees, but since the demand for food is the same it just means someone else will start a farm somewhere else, probably cutting down more trees to do so. So carbon offsetting doesn't work very well.

Also, the trees planted are usually fast-growing trees like pine trees. So you get forests which are monocultures - in other words, there is only one type of tree, and relatively few other forms of life. Meanwhile, the trees that are cut down to make way for farmland (for instance) are often old, natural, tropical rainforests with many different kinds of plants and animals.

And even with pine trees, it will be many years before the trees grow big enough to absorb the carbon they promised. This means there is more global warming in the short term.

Carbon Offsets Indulgences

Carbon offsets are analogous to the indulgences sold by the Catholic church in the 15th century. It allows rich people to pay for their "sins" rather than actually changing their lifestyle.

For example, Al Gore's mansion in Tennessee uses 20 times more electricity than an average person's home (without even considering his other house or place in Washington DC). Instead of actually practicing what he preaches and reducing his electricity usage, he just buys carbon credits (or offsets) so he doesn't have to feel guilty about his extravagant, carbon-heavy lifestyle. (Not to mention that he buys the carbon credits from a company he founded and owns. In other words, he's paying himself.) But since Al is the Messiah of the Church of Environmentalism, he can't be held to the same standards as everyone else.

First answer by ID1079232089. Last edit by Pure.mathmo. Contributor trust: 73 [recommend contributor]. Question popularity: 52 [recommend question]