How does offsetting work?

Greenhouse gases are emitted when fossil-fuelled energy is consumed. One tonne of carbon dioxide (CO2) has the same impact on climate change wherever in the world it is emitted - or saved. You can use less energy, travel less and use public transport, but some emissions are hard to avoid. You can offset the environmental impact of these emissions by reducing somewhere else.You can plant trees, which absorb CO2 out of the air, or you can help someone else to emit less.