The Sun emits radiation, mainly visible and ultraviolet, which passes through the atmosphere and warms the Earth's surface. The warm Earth then emits infrared radiation.
Greenhouse gases, such as carbon dioxide, water vapour and methane, absorb this infrared radiation. The energy makes their bonds vibrate more, and they then re-emit infrared in all directions, including back towards the Earth. This is the greenhouse effect.The natural greenhouse effect keeps the Earth warm enough for life. Human activities, especially burning fossil fuels, are increasing the amount of CO2 in the atmosphere. This enhanced greenhouse effect is causing global warming.How much a gas contributes depends on its concentration, how long it stays in the atmosphere and how well each molecule absorbs infrared. Methane absorbs infrared much more strongly than CO2 but is present in much lower amounts.
Greenhouse gases, such as carbon dioxide, water vapour and methane, absorb this infrared radiation. The energy makes their bonds vibrate more, and they then re-emit infrared in all directions, including back towards the Earth. This is the greenhouse effect.The natural greenhouse effect keeps the Earth warm enough for life. Human activities, especially burning fossil fuels, are increasing the amount of CO2 in the atmosphere. This enhanced greenhouse effect is causing global warming.How much a gas contributes depends on its concentration, how long it stays in the atmosphere and how well each molecule absorbs infrared. Methane absorbs infrared much more strongly than CO2 but is present in much lower amounts.