GLOBAL WARMING Summary from BBC site

What is global warming?

Global warming is the rise in temperature of the earth’s atmosphere. It’s said that by the time a baby born today is 80 years old, the world could be 11 degrees warmer than it is now.

Is global warming bad?

The earth is naturally warmed by rays (or radiation) from the sun which pass through the earth’s 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 global warming is good. But 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.

What are the greenhouse gases?

Greenhouse gases are made out of:

• water vapour
• carbon dioxide
• methane
• nitrous oxide
• ozone
• chlorofluorocarbons (CFCs)

How are extra greenhouse gases produced?

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 global warming?

The ozone layer is another important part of the atmosphere. It’s made up of ozone (a type of oxygen) that 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.

So what could happen?

 

If Earth gets hotter, some of the important changes could happen:

• Water expands when it’s heated and oceans absorb more heat than land, so sea levels would rise.
• Sea levels would also rise due to the melting of the glaciers and sea ice.
• Animals like polar bears, which live on the ice, might die out.
• Cities on coasts would flood.
• 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 hard to grow crops.
• Less water would be available for drinking, showers and swimming pools.
• Some plants and animals might become extinct because of the heat.
• Hurricanes, tornadoes and other storms which are caused by changes in heat and water evaporation may get more common
  

~ by stufffromthelab on April 24, 2007.