White Paper: Cause of Seasonal Changes in Atmospheric Methane Concentrations

A recently published paper Atmospheric methane emissions correlate with natural gas consumption from residential and commercial sectors in Los Angeles (He et al) asserts that winter increases in methane emissions are due to emissions stemming from natural gas consumption during that period of the year in the Los Angeles (LA) metropolitan area. The premise of this paper, however, does not include an important mechanism that is a key contributor to seasonal changes in atmospheric methane concentrations. The mechanism is better described as an enhanced version of the seasonal (summer) decrease in methane due to a phenomenon wherein the combination of longer daylight hours (i.e., higher ultraviolet radiation), atmospheric chemistry, and higher temperatures drive a process resulting in higher atmospheric methane oxidation rates.

In this GTI White Paper, a broader perspective explores all possible causes of the enhanced seasonal changes in atmospheric methane concentrations. Data indicates that an alternative cause of the enhanced seasonal changes in atmospheric methane concentration may be due to an increase in the “methane sink” activity during the summer period.

In addition, we highlight the unlikely assertion that natural gas space heating equipment are a major source of winter season methane emissions.

For more information, contact methane@gti.energy