Trees absorb carbon dioxide and emit oxygen.

CO² warms up the planet by absorbing radiation.

Many scientists believe that the earth is getting hotter because of industrial pollution.

This is the greenhouse effect.

This kind of pollution puts more carbon dioxide and other heat absorbing chemicals into the atmosphere.

If there is a rise in temperature, sea water evaporates more easily and this causes more CO² pollution.

CO² pollution also causes a change in the weather.

We have recently seen hurricanes in the Caribbean,

terrible storms in France and flooding in Mozambique.

If the earth continues to heat up, it may melt the polar ice cap, and parts of the earth will be flooded permanently.

If there are more trees to absorb the CO², it will help to prevent this.

Sometimes we call the capital city's great parks "the lungs of London" for this reason.

DEVELOPMENT

In Britain there are already a lot of uninhabited buildings.

It costs a lot of money to develop these buildings.

It is quicker and cheaper to make new houses.r

Developers prefer to build new housesand leave the others empty - it is the easier option.

But it takes a very long time for a tree to grow - some trees take 40 years to grow.

ENVIROMENT

Mature trees are ecosystems.

This means they are places where a whole community of plants, insects, and animals can eat, live, reproduce and die.

If a wood is destroyed then thousands of insects, birds and small animals lose their homes and their food supply.

Wehn we build on the land the earth loses the minerals that it gets from being part of an ecosystem.

Sometimes the earth is polluted so badly that nothing can even grow on it again.