Greenhouse gases are substances that contribute to the increased greenhouse gas effect and heating of the planet. Different greenhouse gases affect the climate to varying extents.
Large anthropogenic sources of greenhouse gases include combustion of fossil fuels and agriculture. All greenhouse gases are gaseous and occur in air.
The increase of greenhouse gases in the atmosphere is a global issue and measures to decrease the emissions are taken on global as well as local level. Sweden reports emissions of greehouse gases to the United Nations Framework Convention on Climate Change.