This continues the increase in global methane that has been observed globally by NOAA ESRL since 1983. It is almost a 13.4% increase in global mean methane since March, 1984.
This month's 11.2 ppb increase over March 2017, represents the highest rate of increase since December 2015, and if the results remain above a 10 ppb increase in the coming months, as more samples are collected, it will be the first month with an increase above 10 ppb since July 2016.
However, it is the longer trends that demonstrate the accelerating rate of increase of CH4 concentration in the atmosphere.
Since March 2013, global mean CH4 has increased by 46.1 ppb, the highest rate of increase since the collapse of the Soviet Union, and the most since May, 1993. It is also the eleventh month of five year comparison increases over 40 ppb, last experienced in 1992-1993.
The ten year increase, since March, 2008 is 73.6 ppb. This is the highest 10 year change since March, 1999. It is obvious from the data and graphic, that methane continues to increase in concentration and reflects increasing global emissions.
Recent research has attributed the methane increases primarily to growth in livestock production and changes in rainfall in the tropics. However, according to the USDA global markets report, there has not been a major increase in livestock (cattle or swine) production since 2014. We have seen significant increases in CH4 concentration during that time.
|USDA World Markets|
|Total Cattle Beginning Stocks||Total Cattle Production|
|Total Swine Beginning Stocks||Total Swine Production|
However more research is needed to localize sources and particularly to determine if natural gas production is making a higher contribution to changes in methane concentration.
There may be other natural methanogenic sources that need further consideration, but that is another post.