By guest blogger Ray Harrington-Vail of the Footprint Trust

Carbon offsetting has become one of the buzz phases of the last year. It appeals to individuals and businesses that wish to carry on their current lifestyles and practices and buy a bit of green credibility.

But can planting trees really help negate our extravagant planet-damaging ways? The only people who really seem to think this can help are those who are selling the trees.

Planting trees is fun and good for wildlife - but does it offset carbon emissions?

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Planting trees to neutralise carbon emissions has become a big business: £60m worth of trees have been bought in 2007 up from £20m in 2005. By 2010 the market is expected to reach £300m.

Trees, like carrots and any vegetation do absorb carbon during the growing process but this will be released when the plant dies, is eaten or burnt. Most trees do not live to a majestic old age, the majority succumb to disease or predation in their early years.

Most of the trees being planted will only live a few years. To do any good they would have to grow very quickly and then be felled and then sunk into the deep ocean. Alternatively they could be stored where they could not rot - such as used as a building material.

Not destroying tropical forests would also make sense from an ecological and climate change point of view. But planting trees to offset carbon emissions could contribute to global warming if they are planted outside the tropics, scientists believe. Forests in the mid and high latitudes could make their parts of the world more than 3C warmer than would have occurred if the trees did not exist.

The Lawrence Livermore National Laboratory in the USA, has shown that only tropical rainforests are beneficial in helping slow global warming. The problem is that while the carbon dioxide forests use for photosynthesis indirectly helps cool the Earth by reducing the amount of greenhouse gases in the atmosphere, forests also trap heat from the sunlight they absorb. We must also protect moorlands from destruction as these do take-up and store carbon.

The whole idea of planting trees to soak-up carbon is based on a misunderstanding of the carbon cycle and the ability of trees to store enough carbon to make any real effect. The internationally renown Botanist and landscape historian Dr Oliver Rackham, has likened tree planting offsetting schemes to drinking water to stop rising sea levels!

There is increasing criticism from climate scientists of the benefits of forestry schemes to offset carbon emissions. Kevin Anderson, a scientist with the UK’s Tyndall Centre for Climate Change Research, warned recently that offsetting was a dangerous delaying technique that helped people "sleep well at night when we shouldn't sleep well at night".

If you are feeling guilty about all that carbon your putting into the environment it might be better to support a charity, which is helping to develop renewable energy in developing countries. Practical Action funds 'appropriate' or 'intermediate technology' for example, by developing efficient low cost cooking stoves which work from local biomass green fuels. They also support other options such as micro-hydro plants, small scale wind generators and solar lanterns. They state on their website:

Our climate is changing and it’s the world’s poorest people who are hardest hit by devastating droughts, floods and other extreme weather events. This is a massive injustice – climate change is caused by the world's richest countries.

If people wish to really do something to reduce their over-use of fossil fuels they need to change the way they operate. Walk more – fly less… would be a good strap-line. But not likely to make much money for the various off-setting schemes.

(Information from a number of resources including, New Scientist magazine, The Resource Recovery Forum and The Guardian.)