GHG emissions (greenhouse gas emissions) are “gases released directly or indirectly from human activity that contribute to the Earth’s greenhouse effect.”  They trap heat in the atmosphere and cause the Earth’s average temperature to rise. They include water vapour, carbon dioxide, methane, nitrous oxide and ozone.
GHGs are measured in units of carbon dioxide equivalent (CO2e). This makes it easier to compare the emissions from different GHGs, as they all have different warming potentials. For example, methane is around 25 times more potent than carbon dioxide over a 100-year period.
They can come from both natural and human sources. Burning fossil fuels like coal, oil and gas releases GHGs into the atmosphere, as does farming, forestry and other land use.
Reducing GHGs – not just carbon dioxide – is essential to mitigating climate change and its impacts. There are a number of ways to do this, including switching to renewable energy, planting trees and improving agricultural practices.