Saturday, November 1, 2008

Mother Nature's Air Conditioners

The Amazon rainforest has long been recognized as the lungs of the earth due to the oxygenation of the atmosphere it provides. Now the rainforest and all other forests are beginning to be recognized for another role in helping to maintain the environment. The role of global air conditioners.

A new study reveals that forests help to block out some of the sun's heat that is causing global warming and many of the harmful effects of the sun’s rays than was previously thought. We realize now that this makes trees much more important to the Earth’s climate than previously thought.

Scientists in the UK as well as Germany have discovered that trees release a chemical that thickens the clouds above them. These thickened clouds help reflect sunlight back into space and thereby help cool the Earth. This discovery indicates that chopping down forests could accelerate global warming more than was previously believed. It now appears that protecting the world’s forests may be one of the most effective ways of tackling this problem.

Dominick Spracklen, of the Institute for Climate and Atmospheric Science at Leeds University, said: "We think this could have quite a significant effect. You can think of forests as climate air conditioners."

Anyone who lives near a boreal forest knows the distinctive smell of pine trees. The smell is unlike any other. It is a sweet, crisp, pungent smell that helps to clear lungs and sinuses. It is a smell that is familiar to those of us who live in northern regions such as Canada, Scandinavia and Russia. The chemicals that give pine trees their distinctive smell are called terpenes; but, their actual function has puzzled scientists for years. Various theories have evolved over the years: some say the trees use them for communication, others say they could offer protection from air pollution.

Children have known the truth for decades. Pine trees make your living room smell like Christmas when you cut them and decorate them for Santa.

The team in this latest study has found that the terpenes react in the air to form tiny particles called aerosols which turn water vapor in the atmosphere into clouds. Spacklen said the team’s computer models showed that the pine particles doubled the thickness of clouds some 1,000m above the forests reflecting an extra 5% sunlight back into space.

He said: "It might not sound a lot; but, that is quite a strong cooling effect. The climate is such a finely balanced system that we think this effect is large enough to reduce temperatures over quite large areas. It gives us another reason to preserve forests." The scientists say the findings "must be included in climate models in order to make realistic predictions".

As trees release more terpenes in warmer weather, the discovery suggests that forests could act as a negative feedback on climate. They can be used as a natural resource to help dampen future rises in temperature. While the team looked mainly at pine and spruce forests; Spracklen said other trees also produce terpenes, so the cooling effect should be found in other regions, including tropical rainforests.

The research, which will be published in a special edition of the Royal Society journal Philosophical Transactions A, is the first to quantify the cooling effect of the released chemicals.

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