There are six main GHGs, so it's helpful to count them with a single unit: tCO2e. tCO2e stands for tonnes (t) of carbon dioxide (CO2) equivalent (e). "Tonne" is a fancy way of writing metric ton, or 2,200 pounds. “Carbon dioxide equivalent” is a standard unit for counting greenhouse gas (GHG) emissions regardless of whether they’re from carbon dioxide or another gas, such as methane.
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