Global warming is the rise
in temperature of the Earth's atmosphere.

The earth is naturally warmed by rays from the sun.
 They pass through the atmosphere
and are reflected back out to space again.

The atmosphere's made up of layers of gases -
some of which are called greenhouse gases.

They're mostly natural and make up a kind
of thermal blanket over the Earth.


This lets some of the rays back out of the atmosphere,
keeping the earth at the right temperature for animals,
plants and humans to survive (60°F/16°C).

So some think global warming is good.

But most scientists think if extra greenhouse gases are made,
the thermal blanket gets thicker and too much heat
is kept in the earth's atmosphere - that's when global warming's bad.


                           Greenhouse gases are made out of:

-water vapour
-carbon dioxide
-nitrous oxide
-chlorofluorocarbons (CFCs)

They are all natural gases,
but extra greenhouses gases can be made by humans.
Environment experts are especially concerned about carbon dioxide.

How are extra greenhouse gases made?

Although plants absorb carbon as they grow,
extra carbon is released into the atmosphere
when humans cut down trees.

Extra greenhouse gases are produced through activities
which release carbon dioxide, methane, nitrous oxide and
ozone CFCs (chlorofluorocarbons).

These activities include:
-Burning coal and petrol, known as 'fossil fuels'
-Cutting down of rainforests and other forests
-Animal waste which lets off methane

What's the 'ozone layer' got to do with it?

The ozone layer is another important part of the atmosphere.

It's made up of ozone (a type of oxygen).
It protects the earth from too many harmful rays called UVB.

Some greenhouse gasses damage it -
letting in the harmful rays which could raise the Earth's temperature.

                                            What could happen?

If the Earth gets hotter,
these are some of the things that could happen:

-Water expands when it's heated so sea levels could rise.

-Sea levels could also rise due to the melting of the glaciers and sea ice.

-Animals like polar bears - which live on the ice - might die out.

-There could be more floods, especially near the coast and rivers.

-Places that usually get lots of rain and snowfall might get hotter and drier.

-Lakes and rivers could dry up.

-There would be more droughts, making it harder to grow crops.

-Less water would be available.

-Some plants and animals might become extinct
  because they cannot cope with higher temperatures.

-Hurricanes, tornadoes and other storms which are
  caused by changes in heat and water evaporation
  may get more common.


                      What's being done about it?

Every five years,
the United Nations has a meeting called the Earth Summit,
where world leaders agree on what to do about global warming.

In 1997, an important agreement was made
at the UN Conference on Climate Change in Kyoto,
Japan, to cut the amount of gases that industries make.

That agreement came into force in February 2005.

Some people say it won't have any real impact
because America - one of the world's biggest polluters
- has pulled out.

Leaders agree the world can cut the amount of carbon dioxide
that's released into the atmosphere by changing the way power
is produced too.


There are ways you can help cut greenhouse gases
and help stop global warming.

They are simple things, but can make a difference if everyone does them!

·  Recycle glass bottles, jars, newspapers and magazines and tin cans.
Save them and take them to local recycling centres.

·  Re-use plastic shopping bags and envelopes, don't get new ones.

·  Persuade your mum or dad (or whoever does the gardening)
to have a compost heap.

·  Put a brick in a plastic bag into your toilet cistern,
then the toilet will use less water each time you flush.

·  Use paper on both sides.

·  Try to buy products that don't use much packaging.

·  Give unwanted gifts and clothes to a charity shop.

·  Only fill the kettle up with the amount of water you need to boil that time.

·  Don't leave the TV or video on standby.

·  If you get lift to school in a car, take your mates along for the ride.

·  Ask whoever does your washing to use the machine at 40 degrees
- this helps conserve power.

·  Switch lights off when you're not in the room.

·  Get a clockwork mobile phone recharger

·  Have showers instead of baths.

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