The main reason why our planet is getting warmer is because of an increase in greenhouse gases. We need some greenhouse gases to trap heat and keep the planet warm, but too much of them traps more heat than we need and leads to a hotter Earth and a change in our climate.

Human activities over the past 150 years have dramatically increased greenhouse gases levels in our atmosphere. The main causes are:

• Burning fossil fuels like coal and oil to heat our houses, produce electricity and drive our cars
• Destruction of forests and other natural areas
• Agricultural activities such as fertilizer use, rice paddies and livestock