SCIENCE: Oil and gas boom not to blame for methane spike -- study -- Friday, March 11, 2016 -- www.eenews.net Relatively new (I believe satellite) data is that global methane has been increasing last 10-15 yrs. But why? Most have assumed USA fracking. But maybe not. Appears to be ag sources, it tentatively seems.
Some of the potentially runaway methane sources are scary to think about, such as the increased release from the arctic upon thawing of the permafrost and the ice over ancient lakes. I'll try to be more conscientious about reducing my personal methane emissions as well.
If someone here is interested in global methane, they would look at both this recent Schaefer et al in Science (no known relation) and Tian et al in Nature. They take different approaches, look at different data, and might finally be arriving at different conclusions. Before digging into that I'd like to mention that the slowed rate if methane increase 1992-2006 was (at the time) heralded in 'non-mainstream' climate literature as evidence that everything was OK and there were no climate problems. I am unaware of any retractions on that point, with methane increase since returning to the prior upward slope. Now, methane increase has returned to that increase, and we wonder if the cause is more from Ag, high-latitude soils, or fossil-fuel extraction. At first reading, the first paper above argues in favor of increase from non-fossil-fuel sources. I don't yet see that they have separated Ag. from other biological sources. But they do suggest a combination of ruminants (incl. cattle) and wetland rice to be the source of the increase, as opposed to fossil C. Cows& rice may have much increased since 2006, or not. I really don't know. Anyway, as methane is such a good IR absorber, this ought to be examined further.
For release sources, don't forget the cold underwater methane ices / hydrates / clathrates. As ocean waters warm, more of this stored stock should melt and release. Not all of this reaches the atmosphere, but I don't know what fraction is retained and consumed in the water.
quote from the GreenAtom article: Since 2007, methane has been on the rise, and no one is quite sure why. Some scientists think tropical wetlands have gotten a bit wetter and are releasing more gas. Others point to the natural gas fracking boom in North America and its sometimes leaky infrastructure. Others wonder if changes in agriculture may be playing a role. “There is no question that methane is doing some very odd and worrying things,” said Euan Nisbet, an atmospheric scientist at Royal Holloway, University of London. The big question is why. Scientists wonder if they will have the right monitoring systems in place to answer that question adequately.
Aside from look-down satellites, we have very poor ways to know marine methane sources. Traditional oceanographic cruises cost a lot. If this is 'a thing', it might be handled more cheaply via long-range big-drone flights. Those can be fitted to do science instead of launching Hellfire missiles.
Another new publication in Atmospheric Chemistry and Physics, suggests that (oh maybe 1/3) of the recent methane increase can be attributed to fossil fuel extraction. Based on also measuring ethane increases. That molecule does not arise from biogenic processes. But they only have a couple of sites, so the situation appears complex. As so often the case eh? Something for everybody. The way they measure ethane is amazingly complex and will not happen at many other places I suppose.
