Climate change

Greenhouse effect

Some thermal energy from the Earth’s surface escapes into space. If too much thermal energy escaped, the planet would be very cold. However some gases in the atmosphere, called greenhouse gases, trap escaping thermal energy. This causes some of the thermal energy to pass back to the surface. This is called the greenhouse effect, and it keeps our planet warm. Carbon dioxide is an important greenhouse gas.

View of Earth showing how the sun's rays enter the atmosphere. Energy is absorbed by the surface. Some heat passes back into space, but some is absorbed by CO2, becoming trapped within the atmosphere.

Increasing carbon dioxide levels

Humans burn fossil fuels to power cars and other machines, to generate electricity, and to keep buildings warm. Waste gases are released during combustion, including carbon dioxide. As the human population increases, more fuel is used, and more carbon dioxide is released.

Graph shows how carbon dioxide has increased between 1700 and 2000. In the year 1700 there was 0.028% CO2 in the atmosphere, but at around 1850 this began to rise. By 2000, the percentage of CO2 was at 0.035, an increase of 0.007%Human activities have caused the percentage of carbon dioxide in the atmosphere to increase

Global warming

Extra carbon dioxide in the atmosphere increases the greenhouse effect. More thermal energy is trapped by the atmosphere, causing the planet to become warmer than it would be naturally. This increase in the Earth’s temperature is called global warming.

Graph showing how the global average temperature has changed from around 1870 - 2000. The line graph shows an increase in global temperatureThe average temperature of the planet has increased in recent years

The majority of climate scientists agree that there is a link between the increasing levels of carbon dioxide and the increasing temperatures. Global warming is having an effect on the world’s climates.

The impact of climate change

The weather includes the wind, sunshine and rain you see from day to day. The climate is the sort of weather seen over years and decades. Climate change and its effects as a result of global warming includes:

  • ice melting faster than it can be replaced in the Arctic and Antarctic
  • the oceans warming up – their water is expanding and causing sea levels to rise
  • changes in where different species of plants and animals can live

An examination of the evidence for climate change in glacial environments