Why Planting Trees for Carbon Guilt Doesn’t Add Up

I remember an illustration from rainforest campaign publicity in the 1990s that showed the billowing and multi-branched crowns of two trees, with the trunk of each joined at the roots, forming the shape of human lungs. The rainforests are the lungs of the world, it suggested. We breathe out and they breathe in, recycling our atmospheric waste. The basic photosynthesis equation suggests similar - what we put out, plants take in. However the photosynthesis equation is a basic starting point for further scientific investigation, and the lung image conceptualised a process that is broadly true but difficult to measure exactly. In fact, a 2002 article in Nature magazine suggested that far from being dependent on humanity’s next collective exhalation, the forest in the Amazon is in a state of carbon dioxide equilibrium, with its dry regions absorbing approximately the same amount of carbon dioxide that its rivers and wetlands produce.

A forest’s ability to store carbon cannot easily be equated with the carbon emitted from using fossil fuels such as oil. Carbon stored in trees is easily released, and rates of decay for a tree and its leaf litter vary; wildfires, pests and diseases are unpredictable influences; and the availability of nutrients for the tree can vary. Temperature change from global warming is a fairly predictable factor but the changes that this will bring in trees’ behaviour are not.

And although tree-planting is generally thought of as a "good thing", it isn’t always the best course to take for carbon storage. The draining of Finnish peatlands for industrial forestry, for example, has transformed those areas from carbon sinks to carbon sources. The UK’s own precious carbon-storing peatlands are being stripped mainly for use in home gardening. "Preserve a bog" may in some cases be a more appropriate action than "plant a tree".

Larry Lohmann of the environmental and social justice organisation The Corner House points out that, beyond the scientific uncertainties around the carbon absorption capacity of a tree, for forests to be used as carbon storage projects it would have to be ensured that they did not result in carbon being lost into the atmosphere outside the project boundaries. Lohmann suggests that new tree plantations occupying agricultural land would have to be shown to be in no danger of causing forests to be cleared elsewhere to make up for lost food or other crops. Forest products would have to be tracked as their carbon storage capacity may vary massively: some may be burned almost immediately; others may decay more slowly; and other wood may be landfilled, which could mean either long-term carbon storage or dangerous releases of methane, depending on circumstances. People displaced from the new project would have to be monitored to make sure that they did not cut down forests elsewhere or adopt more carbon-consuming lifestyles than they would have done if they had stayed put.

Though some carbon offsetting companies claim to consider land rights issues, not all are so scrupulous. After all, as the Industrial Revolution created the commodity of "labour time", so our Oil Age has made carbon dioxide marketable. As such, carbon storage forestry projects are likely to be located where land is cheapest, leaving the poor to deal with the changes in land and water use that they bring. Lohmann highlights the irony that a community evicted by oil drillers today may tomorrow find itself displaced by forestry planted to deal with the emissions from that oil use.

The carbon market currently includes one company offering an acre of forest in Ecuador for £25, which will apparently absorb as much carbon as is released by powering my television for a year. In theory, could I compensate for my environmental impact from watching I’m a Celebrity by arranging to possess their jungle home? Would another £25 allow me to boil the kettle in the ad breaks? Carbon offsetting claims active intervention for environmental gain while allowing for continued choice for consumers. But such "choice" is only available for a few. Its logic is that it is okay to carry on polluting so long as you have the capital to take control of more of the world’s resources. Its politics is to extend current inequality, where a minority of people have control over the majority of resources, by allocating more resources to that minority - but this time to deal with the waste from their first round of resource use! This distracts from the political need for climate justice, and the ecological need to shift away from current levels of consumption and reduce emissions at source.

A British advocate of using forestry for carbon storage said it was "like being polite enough to shut the door behind you when you leave the room". A more realistic exit analogy is hearing the stable door slam to, as you peg it with the last of the family silver, which you were too overburdened to carry last time.