Fugitive emissions are released during gas, oil and coal production. When fossil fuels are extracted and produced, greenhouse gases are released into the atmosphere via deliberate releases (aka venting) or innumerable leaks in equipment. What is Mt CO₂-e? Emissions are a combination of gases. Most are Carbon Dioxide (CO₂). The other gases are measured as a Carbon Dioxide equivalent (CO₂-e) based on the amount of heat they trap in the atmosphere. They’re measured in Million Tonnes (Mt).