What Is Global Climate Change ?

What Is Global Climate Change ?

Greenhouse gases keep our planet warm. They exist naturally in the atmosphere, heating it by trapping energy that has originally come from the Sun. This process is called the greenhouse effect. Without the greenhouse gases the surface of the Earth would be as cold as the surface of the Moon (about -18 degrees Celsius or °C). In fact the typical surface temperature of the Earth is about 15°C.

Changing Temperatures

Measurements taken from all over the world, however, have shown that the global climate is changing. In the last 100 years the atmosphere has warmed up by about half a degree Celsius.

Also during this time humans have been emitting extra greenhouse gases, which are the result of burning fossil fuels (like coal, oil and gas). These gases include carbon dioxide, methane and nitrous oxide

Greenhouse Gases

It is thought that the man-made emissions of greenhouse gases, from the increased use of fossil fuels, are responsible for some of the warming of the global climate during the 20^th century. The extra greenhouse gases in the atmosphere trap more energy and therefore enhance the greenhouse effect. This may cause more warming. Greenhouse gases are also released by the exhausts of motor vehicles. The cutting down of rain forests also releases carbon dioxide, which is a greenhouse gas and causes global warming.

Natural Changes

There are also natural ways in which the climate can be altered. Volcanoes release gases, whichmix with water vapour in the airto make aerosols, and cool the atmosphere. Changes in the Sun's energy and the circulation of the ocean also affect climate.

The Future

If the Earth continues to warm as climate models have predicted, the temperature at the Earth's surface may be 3°C warmer by 2100 than it is today. This rapid change in temperature would be harmful to many ecosystems, and many species of plants and animals

Impacts

Climate change will affect rainfall, sea level and storm

events, and humans would also be affected by these factors. Food crops would be altered, as well as forests and water supplies. People’s health will also be affected.