Arctic Atmospheric Methane Trends 2013

It’s been a while since we’ve looked at methane trends in the Arctic atmosphere (just a little under a year in fact).  This important greenhouse gas has been on the rise over the past several decades, though that rise has not been nearly as steady as CO2. What’s worrisome to those who follow methane is the return to higher growth rates of the gas over the past few years.  This chart shows the atmospheric measurement of methane at Point Barrow cover the last 2.5 years:

What I’ve highlighted here in red are a few interesting features of the methane levels that are worth mentioning.

First, the horizontal red bar shows the lowest boundary of the yearly methane measured a few weeks ago. Methane always hits a low annual concentration at Point Barrow around the middle of the year, usually in June as part the natural fluctuations.  This year we saw the highest low point ever recorded.  This is significant because it shows the underlying long-term growth rate.  If you compare this year’s low point to last year’s, you get a sense of the upward turn in the atmospheric methane concentrations.

At the top of this graphic in the large red circle are several “anomalous” readings that were recorded over Barrow last year just about the time that GAC-2012 was hitting.  These are huge outliers, but because there were several of them occurring all about the same time, we can also assume they were valid data in the sense that it was really being recorded properly.  In direct email discussions with staff at Barrow station at the time, they characterized these as “likely” local anthropogenic sources, i.e. outgassing from drilling rigs, etc.  Note the word “likely”.  These samples are sent back to a lab for analysis that can better describe the sources.  My hunch, and again, this is only a hunch, is that GAC-2012 or simply the very low ice levels of last summer or some combination, may have brought up more methane and caused these very high anomalous readings. It is also important to note that all the data points in the graph that are orange have yet to be fully validated– though they are in the vast majority of cases.

Finally, in the small red circle is one the latest readings from Barrow.  It continues to show the higher long-term upward trend is accelerating and also shows the remainder of 2013 should be interesting to watch, as it will likely show the strong growth rate of methane in the Arctic atmosphere. Though the level will oscillate up and down a bit between now and its annual peak in early 2014, we should monitor the rest of the summer Arctic melt season for the kinds of “anomalies” that we saw last year. I will especially look for a period of anomalously high levels should another large cyclone hit in August or even September when sea ice is at its lowest.

The bottom line of all this is that methane levels remain an important metric to gauge both current and potential future changes in the Arctic climate, and the trends should be of great concern.

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Addendum by Neven:

Thanks go out to R. Gates for his update on methane. I’m taking the opportunity to draw attention to this effort to get methane levels back to 1250 ppb, much like the 350 movement is doing for CO2: 1250now.org

There is also a very cool interactive website that allows one to track methane in the atmosphere everywhere on the planet: Methane Tracker. The site is still in the pre-alpha phase, but when it’s finished, it’ll be announced here in a separate blog post.