So what is this thing called the greenhouse effect?

The greenhouse effect is actually a natural thing. We need it to keep the earth warm so that things can live and grow. Without it, the earth would be too cold to support life. Greenhouse gases (which include carbon dioxide and ozone) form a blanket which stops the sun's heat from being reflected back out into the atmosphere. It's a bit like the way the glass ceilings and walls in Dad's greenhouse keep the plants warm.

However, if these gases are allowed to increase to dangerous levels, too much heat will be trapped, and our climate will change. Unfortunately, this may be already happening. The burning of fossil fuels, such as coal and petroleum, the clearing of native forests for farms, and the use of CFCs in air-conditioning and refrigerators, have all contributed to the amount of carbon dioxide and ozone in the atmosphere.

How forests can help to slow down the greenhouse effect

Forests can play a huge part in helping to reduce the levels of carbon dioxide in our atmosphere. As they grow, trees absorb carbon dioxide from the air and replace it with oxygen. They store carbon in their trunks, branches and leaves. And young trees are able to do this much better than older, fully grown trees.

Young regrowth forests have a big appetite for carbon. Growing trees is a great way of taking carbon out of the atmosphere and storing it as wood. But wait - there's more!

Housing products made from wood need less energy to make than other building materials, such as steel, concrete or aluminium. When these materials are being manufactured, fossil fuels are burnt, and lots of carbon dioxide is released into the atmosphere. This contributes to the greenhouse effect.

But the carbon that trees have absorbed from the atmosphere gets stored in the wood. So long as the wood isn't burnt, or allowed to decompose, the carbon will stay in there for many generations.

An average-sized house with a wooden frame has removed 7.5 tonnes of carbon from the atmosphere, because the carbon is now stored in the wood. However, a house with a steel frame has actually added 2.9 tonnes of carbon to the atmosphere.

Timber is a more 'environmentally friendly' building material than steel and other metal products, concrete or plastics.