What is Global Warming?
The rise in temperature in the earth's atmosphere is known as Global Warming
How Does it Happen?
The earth's atmosphere is made up of layer of gases, many of which are called 'greeenhouse gases'. Most of these are natural gases and form a thermal blanket around the earth. As greenhouse gases build, the blanket is made thicker. As the suns rays hit and heat the earth, they bounce back out of the atmosphere but cannot escape throught the thick wall of gas. The rays are trapped and make the atmosphere hot. This is potentially very harmful to all life on earth.
What are Greenhouse Gases?
Greenhouse gases are those that can absorb and emit infrared radiation.In order, the most abundant greenhouse gases in Earth's atmosphere are:
- water vapor (H2O) - from liquid evaporation
- carbon dioxide (CO2) - from human and animal respiration
- methane (CH4) - from animal waste
- nitrous oxide (N2O) - laughing gas
- ozone (O3) - formed from dioxygen by the power of ultra-violet light
Greenhouse gases are also produced by burning fossil fuels such as coal, oil and natural gas; deforestation and animal waste.
What Happens if the Earth Heats Up?
The damage caused by global warming could be great. In particular, the natural habitat of polar bears in the Artic Circle could be devastatingly affected. They live, feed and breed on the sea ice. Global warming is causing this sea ice to melt and so the animals have little or no habitat left. the warming seas also cause the artic sealife to migrate to better waters therefore removing the only food sources for the polar bears to survive on.