Methane, the primary component of natural gas and a greenhouse gas (GHG), is released into the atmosphere during production and through leaks and operational venting during delivery. Greenhouse gases warm the earth by absorbing energy and slowing the rate at which the energy escapes to space. Different GHGs can have different effects on the Earth's warming called global warming potential (GWP). The GWP for a GHG is determined based on the gases' ability to absorb energy and how long the gas stays in the atmosphere.
Methane has a higher ability to absorb energy than the most common GHG, carbon dioxide. This means that when initially released, methane has a greater impact on global warming. However, the lifetime for methane is significantly shorter meaning that this effect lasts for a shorter period of time than it does for carbon dioxide. Depending on the period of time considered, methane has a GWP of 84 (if considered over a decade) or 32 (if considered over a 100-year period). In November 2017, a number of gas companies signed a set of Guiding Principles on Reducing Methane Emissions across the Natural Gas Value Chain outlining specific steps associated with reducing methane emissions.
Natural gas also releases GHGs when combusted:
However, when combusted methane (CH4) is converted to CO2, which is a less potent GHG than methane. And when used in place of coal as a fuel source for electric generation, natural gas reduces GHGs per MWh by about a factor of on average 50% .