The Earth's climate is changing because of the effect man's activities have had on the atmosphere and the consequences are already being experienced? terrible storms, floods, intense heat and prolonged drought.The future of life on Earth is threatened but forests can help to slow the process of climate change? these web pages explain how.

Start with this brief overview and then visit the relevant sections of the site for more detailed information.

Wood and Mankind

The first humans were very dependent on wood? most of the land was covered with forests that provided them with shelter, fuel and food (nuts and berries). The forests were also the habitat of the animals they hunted.

But, when people began to grow food crops and keep domestic animals, the forests were cut down to make space for fields, farms and villages.

Grazing animals turned loose in woodland ate nuts and new seedlings which meant that the forest areas shrank even more quickly. And, as the human population grew and skills developed, more and more wood was used , for fuel, buildings, carts, boats, ships, furniture and all kinds of tools and equipment. A lot of forests were cut down to feed this huge demand.

Then, in the 19th and 20th centuries new materials and sources of energy were discovered and substituted for wood? new metals, plastics, concrete, etc. But, the rapid development of towns and cities meant that although less wood was being used, the forests were still shrinking.

Factories and houses burning coal; power stations burning coal, oil and gas to make electricity; the rapid increase in motor vehicles? all combined to cause atmospheric pollution and there were serious public health problems. People recognised that trees are good for the air , they produce oxygen and remove carbon dioxide by their natural processes. In many countries there were campaigns to save trees and use alternative materials instead of wood.

Then, in the 1980s and 1990s it was realised that these alternative materials take a lot of energy to produce and are very harmful to the atmosphere because when coal, oil and gas are burned to make electricity, large amounts of carbon dioxide are released. The ever-increasing levels of carbon dioxide in the air began to prevent the heat of the sun from radiating back into the outer layers of the atmosphere and then harmlessly away into space.? Man?s activities have created a global greenhouse and the worlds weather is warming up? this is a threat to the future of life on earth.

Today, people are being urged to use more wood to help protect the environment. This is because if more wood is used, more trees will be planted to meet the increasing demand. If there are a lot more trees .then more carbon dioxide will be taken out of the air and, at the same time, less carbon dioxide will be released because we will be using less of the high energy materials like steel and concrete.

By using more wood we could slow down the effects of global warming.

Climate Change

The Earth's climate is getting hotter. This is because many human activities produce greenhouse gases. these gases trap the heat of the sun inside the Earth is atmosphere creating the greenhouse effect.

The 3 main greenhouse gases are:

?Carbon dioxide? released when coal, oil and gas are burnt for fuel.

?Methane? released by rotting vegetation and the digestive processes of grazing animals.

?Nitrous oxide? released through soil cultivation and use of nitrogen fertilisers.

Methane is a very potent greenhouse gas. it is 20 times more effective at trapping heat in the atmosphere than carbon dioxide.

Trees reduce the effects of global warming because they take in carbon dioxide. the most common greenhouse gas - through their leaves.
Carbon dioxide is a source of food for trees , they break it down using water and oxygen to make soluble carbohydrate? sugars. The sugars are made into starch for storage and the starch becomes cellulose the building material for the structural cells of the wood. Cellulose is made up of long chains of carbon and hydrogen atoms? in this way the carbon becomes a part of the growing tree. As long as the tree is in the ground it takes in more and more carbon dioxide and when it is cut down; the carbon stays locked up in the wood products made from the sawn lumber.

New Zealand is lucky because about 30% of the country is covered in trees and these help to soak up some of the carbon dioxide that New Zealand's growing population is producing through power generation, cars and industrial activities. But not as many trees have been planted in recent years? only 6000 ha of new forest was planted in 2005 compared to 40,600 ha in 2003 and a peak level of 98,000 ha in 1994.This drop is because of complex economic and political factors.
The Kyoto Protocol? a global initiative to fight climate change? has set greenhouse gas emission targets for all the countries who signed up to the treaty. The aim is to cut emissions by 10% by 2012. Estimates of how much carbon any country is locking up in its forests will be taken into account to help meet the targets.
When New Zealand signed up to the Protocol in 2002, the Government was confident that it would have plenty of carbon credits to help to meet its target but now planting levels have dropped, there is likely to be a shortfall and New Zealand will have to buy credits from other countries who have a surplus.This could cost as much as NZ$1 billion.
New Zealand needs a lot more trees to offset its increasing greenhouse gas emissions.
So, the promotion of wood products to stimulate demand and increase forest planting is important to New Zealand. People must begin to understand all the good reasons for using wood and why using other materials like steel, aluminium and concrete will only make global warming get worse.
The energy needed to make a cubic metre of aluminium produces 6325 kg of carbon

The energy needed to make a cubic metre of steel produces 8117 kg of carbon

But a cubic metre of wood represents a 228 kg reduction in the amount of carbon in the atmosphere.This is because carbon is locked up in the wood and the preparation of the timber for market does not need much electricity or fuel? compared to the other materials.
Wood is a very environmentally friendly material to use but it also has many other qualities, for instance:
- it looks good
- it is strong but light in weight compared to steel and concrete
- it is easy to handle and install
- it is flexible and so can tolerate high winds

?Using more wood does mean that people will have to go back to living in old-fashioned buildings or change their lifestyle. Wood not only looks good, it also performs well and modern wood products are very versatile? architects design wonderful structures using wood? not just houses but even public buildings like airports and concert halls.

See also...

• Introduction
• Remarkable pine
• The frefered Species
• Use of Radiata Pine
• Properties