An action or activity that balances the emission of carbon dioxide or other green gases into the atmosphere. "A carbon offset credit is a transferrable instrument certified by governments or independent certification bodies to represent an emission reduction of one metric tonne of CO2, or an equivalent amount of other GHGs" - Carbon Offset Guide A carbon offset is any activity that compensates the emission of carbon dioxide (CO2) or other greenhouse gases (measured in carbon dioxide equivalents ) by providing for an emission reduction elsewhere" - Britannica