Forest carbon credits aim to offset pollution

WASHINGTON (AP) — For years, airlines have offered passengers concerned about climate change an option: For an extra fee, cancel carbon dioxide pollution from their flight quota, paying to protect trees.

This is the idea behind forest carbon credits. Trees absorb carbon from the atmosphere. Forest carbon credits are promises that companies, individuals and governments can purchase to help tackle their emissions by paying to plant or protect trees. Here’s a look at this type of carbon credit.


Imagine a forest at risk of being cut down to make pastures for livestock or fields for crops. A broker comes along and promises to pay the owner of the forest – which may be a government – to prevent this from happening.

The land is formally designated as a carbon credit project. After that the trees should not be cut down or destroyed by fire. The developer sells these promises and keeps a portion of the money. Far away, a polluting company buys the credits instead of reducing its emissions by a certain amount.

Trees store carbon in their tissues, which means that the taller and healthier a tree grows, the more carbon it can store. Soil and vegetation also store carbon. When a tree is cut down, the carbon stored in it is often released into the atmosphere. If trees are ground into large chunks of wood, some of the carbon remains stored.


A forest carbon offset, like any carbon offset, equals one metric ton of carbon dioxide that is avoided, removed, or absorbed. A typical passenger car emits about 5 tons of carbon dioxide annually, according to the US Environmental Protection Agency.

Forest carbon offsets are a subset of the multibillion-dollar carbon “offset” market.

There are three main types of forest carbon offsets: credits that sequester carbon by replanting trees, those that protect trees at risk of being felled, and others that promise to improve the management of a forest and increase its carbon storage.

How do trees sequester carbon?

Trees absorb carbon through their leaves, making them crucial for maintaining a livable climate. Through photosynthesis – the process within plants that turns sunlight into chemical energy – they breathe out oxygen as a byproduct. Carbon is stored permanently in the fibers of a tree until it dies and decomposes.

Deforestation accelerates climate change in a couple of ways: It stops plant photosynthesis, so trees no longer absorb carbon. It is also often accompanied by burns, which release a lot of carbon dioxide.


The same problem that faces all types of carbon offsets: Do they really work?

The market for forest carbon offsets has grown dramatically over the past decade, with many policy makers seeing them as a way to combat climate change and even finance a transition to renewable energy. However, environmental groups, scientists and other experts say compensation programs can be misleading.

“The problem here is that most voluntary carbon markets are self-regulating,” said Arnaud Brohe, chief executive of Agendi, a climate consultancy and expert on carbon markets.

Assessing the climate benefit of a credit is often difficult. For a forest carbon credit to be viable, it has to do something for the environment that wouldn’t otherwise take place, a crucial concept known as ‘additionality’. Credits are only valid if those trees were at an active risk of being felled. If the trees were already protected, the offsets don’t make sense.

Another problem is loss, which is when protection of one tract of forest leads to deforestation in another. There are also sometimes double counting problems, when the same credits are counted in two different ledgers. For example, with limited regulation, credits issued for protected trees in one location could be counted by that country plus the country that bought the credits or some other entity.

Experts say sellers of forest carbon offsets often exaggerate the environmental benefits.

“Even though the projects may end up protecting and conserving some lands, the question is how much?” said Danny Cullenward, a California-based energy economist and attorney who studies carbon emissions.


The Associated Press’s climate and environmental coverage receives support from several private foundations. Learn more about AP’s climate initiative here. The AP is solely responsible for all content.

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