Decline in CH4 Flask Monitoring as Atmospheric Methane Increases

Live Science posted an article last week with interview excerpts from Ed Dlugokencky, an atmospheric chemist with NOAA's Earth Sciences Research Laboratory in Boulder, Colorado. He is one of the most important scientists involved in collecting green house gases from global monitoring sites and maintaining those records.

His comments quoted in the article add urgency to preservation of the monitoring system, and also to improving current and future satellite based methane monitoring. (More on this in later posts.)

"We've had about a 25 percent decrease in the number of air samples measured from the global cooperative network," Dlugokencky told Live Science. "If we want to understand what is happening [with methane], we're going in the wrong direction to do that."

"In the past six years, funding for part of the network — the collection of air samples in flasks — has not kept pace with cost increases."

He attributes the renewed increase in atmospheric CH4 after 2007, "likely due to increased tropical wetlands emissions. The recent string of La Niña years has meant more rainfall in the tropics, leading to more methane."

Dlugokencky added, "We can pretty much tell what's happening at a global level, but if we want to understand what's happening in different regions, we really need to have a denser measurement network and a combination of different approaches, like aircraft and tall towers."

What he does not include in this mix is an increase in satellite observations such as those available from the AIRS and IASI instruments, which would enhance our understanding of CH4 distribution and concentration closer to their sources and global distribution over far more area than the scattering of monitoring stations. See ESRL for the global monitoring data: http://www.esrl.noaa.gov/gmd/ccgg/data-products.html

The article claims that "NOAA complements its air-sample measurements with continuous measurements at six observatories — in Hawaii, Alaska, Greenland, Antarctica, American Samoa and California — and tall towers throughout the United States."

However the network is far more complete with numerous data collection locations available in the ESRL global monitoring network. See http://www.esrl.noaa.gov/gmd/ccgg/index.html

One more significant item regarding Arctic methane. Live Science intimates that Dlugokencky holds the view that "the warming Arctic could add significant amounts of methane gas to the atmosphere as permafrost melts and releases huge quantities of gas trapped in previously frozen ground. While some studies indicate methane may already be escaping from the Arctic ground, atmospheric levels of methane in the Arctic have not increased yet." (Underlined emphasis is mine)

This perspective is debatable. Given the availability of the IASI methane data, this view needs further challenge. More on this in future posts.

Over all, however, the flask monitoring network is of great importance in methane tracking, given its long term readings. However, it needs careful consideration on what it exactly tells us, and how well it fills that role. The challenge to the ground network is that it only monitors specific locations, and their are major gaps in the network, especially in the Arctic and Antarctic.

Read more of the Live Science article at: http://www.livescience.com/42986-methane-greenhouse-gas-monitoring-threatened.html