NOAA: Unusual Arctic Warmth, Tropical Wetness Likely Cause for Methane Increase:

Unusually high temperatures in the Arctic and heavy rains in the tropics likely drove a global increase in atmospheric methane in 2007 and 2008 after a decade of near-zero growth, according to a new study. Methane is the second most abundant greenhouse gas after carbon dioxide, albeit a distant second.

NOAA scientists and their colleagues analyzed measurements from 1983 to 2008 from air samples collected weekly at 46 surface locations around the world. Their findings will appear in the September 28 print edition of the American Geophysical Union’s Geophysical Research Letters and are available online now.

“At least three factors likely contributed to the methane increase,” said Ed Dlugokencky, a methane expert at NOAA’s Earth System Research Laboratory in Boulder, Colo. “It was very warm in the Arctic, there was some tropical forest burning, and there was increased rain in Indonesia and the Amazon.”

In the tropics, the scientists note, the increased rainfall resulted in longer periods of rainfall and larger wetland areas, allowing microbes to produce more methane. Starting in mid-2007, scientists noticed La Niña conditions beginning, waning and then intensifying in early 2008. This kind of climate condition typically brings wetter-than-normal conditions in some tropical regions and cooler sea surface temperatures in the central and eastern tropical Pacific Ocean. It can persist for as long as two years. In the United States, La Niña often signals drier-than-normal conditions in the Southwest and Central Plains regions, and wetter fall and winter seasons in the Pacific Northwest.

Observations from satellites and ground sites suggest that biomass burning – the burning of plant and other organic material that releases carbon dioxide and methane – contributed about 20 percent, of the total methane released into the atmosphere in 2007.

However, during the scientists’ 2007 measurement of methane for northern wetland regions, including the Arctic, temperatures for the year were the warmest on record. This temperature increase coincided with the large jump in the amount of methane measured in that area.

Dlugokencky and his colleagues from the United States and Brazil note that while climate change can trigger a process which converts trapped carbon in permafrost to methane, as well as release methane embedded in Arctic hydrates – a compound formed with water - their observations “are not consistent with sustained changes there yet.”

I’ve written endlessly about the leap in atmospheric methane levels since late 2006, and pointed out that we should not leap to conclusions about this most recent surge in methane levels. (See Methane checkpoint for the latest installment and a graph of the observations.) My main point was simply that we’ve seen other multiple-year jumps in the methane level, so we shouldn’t leap to the conclusion that what we’re seeing now is either the permafrost or hydrates time bomb going off. Of course, we should also not assume that it isn’t either or both of those scary things, either.

The paper described above (which I haven’t seen, but I will try to obtain a copy) seems to say that it’s a mix:

• 20% of all methane release, not just the additional increment, was from biomass burning. This raises some interesting questions–how much CO2 was associated with this burning, and how much more biomass can we expect to see burn because of climate change-induced conditions? (I’m also wondering how much of that increment came from biomass burning. It seems that if burning accounted for 20% of all methane emissions in the period in question then it would have to account for nearly 100% of the incremental amount.)
• As for the Arctic wetlands emissions, I have no idea what a “large jump in the amount of methane measured in that area” means in terms of metric tons/year.
• The last graf I quoted above seems to address the hydrates and permafrost time bombs, in that order. The fact that the authors are quoted as saying their observations “are not consistent with sustained changes there yet” sounds to me like they (and the author of the above piece) were and are acutely aware of the implications of hydrates and/or permafrost being the source. Note their careful wording, which I interpret as meaning they have no evidence to link the observed methane emissions to those two particular mechanisms, but that a lack of such evidence should not rule out those coming into play in the future. Sounds to me like the work of true scientists, exhibiting an appropriate level of caution. After reading some of the bare knuckles, ignorant idiocy online, this is refreshing.

I have to wonder if this Arctic wetlands effect explains the prior run-ups in atmospheric methane we’ve seen in recent decades. (Again, see the graph in Methane checkpoint.) Perhaps we’re seeing an interaction between climate change (which is accelerated in the Arctic, compared to the overall average) and geography–as warming progresses, different sections of land cross temperature boundaries and become susceptible to greater methane production from wetlands.

I hope that the study is correct, and that the permafrost and hydrates are not contributing significantly to atmospheric methane levels. If those sources and mechanisms, which I’ve long considered the very real monster under our climate bed, came into play, it could be spectacularly bad news.

Of course, the big question is how far away are we from hydrates and permafrost being triggered in large enough quantities to speed up warming. (We’ve surely all seen the videos of scientists poking holes in Arctic ice and then lighting the blast of released methane, or heard the stories of large numbers of bubbling sites in the Arctic.) At some point warming will set off those two time bombs. A secondary question is whether the wetlands emissions identified in this study are enough of a “kicker” to push us toward the point where the hydrates and permafrost get into the act.

For now, I consider this moderately good news. But until we find out how much methane and CO2 we’ll get from biomass burning, and how much more methane we’ll see from the wetlands effect, it’s still premature to pop any champagne corks.