Why global warming happens?
We control our body temperature by dressing heavily when it is cold and dressing lightly when it is hot.
Throwing a coat over your shoulders on a warm spring day would make anyone feel hot.
In the same way, the earth has its own clothes to control its temperature.
This function is fulfilled by the atmosphere, invisible to us, that wraps around the earth.
Without the earth's atmosphere, the air temperature on the earth's surface would be far below zero.
The carbon dioxide we discharge in the process of living our lives also becomes a constituent in the atmosphere.
When we release carbon dioxide it is like putting more clothes on the earth, leading to increased temperatures in the air from the ground surface up to an altitude of almost 20 kilometres.
Carbon dioxide is causing all the fuss now, but there are many other gases that also cause warming.
Other gases discharged through human activities such as methane gas, and chlorofluorocarbons, made famous by the ozone hole, are not thought to have as big an impact on global warming as carbon dioxide, but in the same amounts they cause more temperature rise than carbon dioxide, so concerns about them are rising.