Why climate change happens
To understand global warming, we need to understand what controls the temperature on Earth. This is best explained by the greenhouse effect.
The Sun emits radiation, which provides us and the Earth's ecosystems, with light and heat. Some of the Sun's radiation is absorbed by the Earth's surface, while the rest is reflected from the surface of the Earth, and either escapes into outer space, or is retained within our atmosphere by the gases that form a blanketing layer around the Earth's surface. The gases that remain in the atmosphere are called 'Greenhouse Gases' and include CO2 (carbon dioxide) and methane.
When these greenhouse gases in the atmosphere trap the Sun's radiation, the Earth's surface temperature increases - like the glass windows of a greenhouse.
Until recently the concentration of greenhouse gases in the atmosphere remained pretty much constant for 10,000 years. However, in the last 100 years or so, the concentration of these gases, like CO2 (carbon dioxide), has increased rapidly. Many scientists believe that this has caused more infrared heat to be trapped around the surface of the Earth by the atmospheric blanket of greenhouse gases and that this is the cause of global warming. It is this rapid warming that is causing scientists' such concern.
The rapid increased concentration of these gases is largely attributed to human activities, such as burning fossil fuels and cutting down large areas of forest.