Was doing a fundraiser saturday night, trying to finance my trip to AGU in San Francisico next month. Somebody popped the Methane question. My “more information needed” answer probably did not satisfy him. But, ..
more information is needed.
As a PhD student in 1991, I placed my first methane-emissions measurement chamber on the Alaskan tundra. My goal was to reduce uncertainties in the estimates of greenhouse-gas emissions from the Arctic. The first assessment report from the Intergovernmental Panel on Climate Change (IPCC) had been released, and methane emissions from wetlands in the region had been identified as a ‘wild card’ in the climate system. They still are.
I followed the best practices at the time. My gas samples were handled according to protocols and calibrated against ‘god bottles’ of gases with precisely known concentrations — part of the US National Oceanic and Atmospheric Administration’s network of standards for atmospheric trace gas analysis. Other scientists carried out similarly careful work. More than 20 years on, Arctic methane emissions remain just as uncertain.
The reason is natural variability. Methane fluxes can vary by a factor of two or more from year to year, which is as large as the measurement uncertainties that we once set out to reduce1. So the range for global wetland methane emissions recognized today2 (140–280 teragrams of methane per year; see ‘Methane sources‘) is the same as it was in 1974, when the first global methane budget was published3.
Methane is a powerful greenhouse gas — it is some 25 times stronger per tonne than carbon dioxide in warming the climate. So not knowing why it varies in the atmosphere is a serious problem. Worse, tipping points in the climate system that cause sudden surges in methane release from the Arctic would have a substantial effect on global temperatures.
To learn what governs this variability, we need to expand ground-based networks across the polar region for monitoring carbon release from ecosystems and its exchange with the atmosphere. Attention should focus on the most prolific sources in wetlands, lakes and coastal areas.
Wetlands, many of which are at high latitudes, are the main global source of naturally occurring methane in the atmosphere. The gas is also produced in the sediments of lakes and in coastal-shelf areas such as the Laptev Sea, including highly uncertain releases from storage in methane hydrates in deep sediments.
There are many unknowns. How thawing soils release methane is poorly understood. The biogeochemistry of the landscapes that result when permafrost thaws is not known. We cannot even predict why some areas become wetter as permafrost thaws, whereas others become drier.
Depending on factors including temperature, snow duration and soil moisture conditions, methane emissions from permafrost wetlands can vary by factors of 2–4 from year to year4. This variability is clear in atmospheric measurements of the gas, but a lack of ground-based data makes it hard to locate the methane sources responsible.
In 2007, for example, changes in biogenic (probably wetland) sources were implicated in a sudden rise in atmospheric concentrations of methane in the Arctic after years of stagnation, on the basis of the gas’s isotopic composition, among other evidence (see ‘Atmospheric variation‘). Suspected sources such as the West Siberian lowlands could not be pinpointed because there were no local flux measurements4. The lack of continuous and geographically distributed flux monitoring makes it difficult to estimate even the likelihood of particular sources being responsible.
Methane monitoring in the Arctic is expensive. It requires sophisticated equipment — such as laser spectrometers — and demanding logistics, including power supplies for remote stations. Research projects, therefore, typically focus on one site, and run for only a year or two. Longer-term monitoring programmes, which may document climate, hydrology, phenology and population dynamics of birds and mammals, rarely measure carbon fluxes, because it is technically challenging. One that does is the Greenland Ecosystem Monitoring programme, which started at the Zackenberg Research Station. It has recorded substantial methane-flux variations for almost a decade in northeast Greenland.
Such multi-year studies show that, although there is some connection between the amounts of methane released from one year to the next, accurate forecasting is difficult5. The state of the ecosystem at the point that it freezes in the autumn affects emission patterns the following year. Such circumstantial factors could induce a three- to fourfold difference in emissions between years5. They also highlight the importance of extending monitoring beyond the growing period into the frozen season, in both spring and autumn. The assumption that ecosystems become inactive when freezing starts has been proved utterly wrong.
Civil and military collaborations should also be sought for monitoring methane point sources. Countries in the Arctic Council together spend more than US$9 billion per year on military activities in the region, which is of increasing geopolitical and commercial interest owing to the retreat of sea ice (see go.nature.com/kqsga3). A small share of the funds could support scientific research that aligns with military interests, such as the factors affecting Arctic thaw. Ships, drones, aircraft, satellites and methane-measurement platforms on land could be shared, for instance. The Canadian Coast Guard and Danish navy fleets already collaborate with public scientific institutions in the Arctic.
Don’t forget rising atmospheric methane levels due to fugitive losses of natural gas wells => New Cornell study shows urgent need to reduce methane emissions
Also losses at oil wells, pipeline losses, and losses at fossil fuel processing facilities, not to mention what is released from coal or tar sands mining (and I don’t recall any recent studies on those two). Peter is right. More information is needed, and considering how potent methane is as a GHG, and how much of it there is in the permafrost and in seabed clathrates, we need to get moving fast before “we’re F**Ked”, as Dr. Box put it.
Reported earlier this month:
http://www.scientificamerican.com/article/the-biggest-methane-leak-in-america-is-in-new-mexico/
Yale Forestry says trees are a source of methane worth noting:
Diseased trees in forests may be a significant source of methane that causes climate change, according to a study by researchers at the Yale School of Forestry & Environmental Studies (F&ES) published in Geophysical Research Letters.
Sixty trees sampled at Yale Myers Forest in northeastern Connecticut contained concentrations of methane that were as high as 80,000 times ambient levels. Normal air concentrations are less than 2 parts per million, but the Yale researchers found average levels of 15,000 parts per million inside trees.
“These are flammable concentrations,” said Kristofer Covey, the study’s lead author and a Ph.D. candidate at Yale. “Because the conditions thought to be driving this process are common throughout the world’s forests, we believe we have found a globally significant new source of this potent greenhouse gas.”
The estimated emission rate from an upland site at the Yale forest is roughly equivalent to burning 40 gallons of gasoline per hectare of forest per year. It also has a global warming potential equivalent to 18 percent of the carbon being sequestered by these forests, reducing their climate benefit of carbon sequestration by nearly one-fifth.
“If we extrapolate these findings to forests globally, the methane produced in trees represents 10 percent of global emissions,” said Xuhui Lee, a co-author of the study and the Sara Shallenberger Brown Professor of Meteorology at Yale. “We didn’t know this pathway existed.”
The trees producing methane are older — between 80 and 100 years old — and diseased. Although outwardly healthy, they are being hollowed out by a common fungal infection that slowly eats through the trunk, creating conditions favorable to methane-producing microorganisms called methanogens.
“No one until now has linked the idea that fungal rot of timber trees, a production problem in commercial forestry, might also present a problem for greenhouse gas and climate change mitigation,” said Mark Bradford, a co-author and assistant professor of terrestrial ecosystem ecology at F&ES.
Red maple, an abundant species in North America, had the highest methane concentrations, but other common species, including oak, birch, and pine were also producers of the gas. The rate of methane emissions was 3.1 times higher in the summer, suggesting that higher temperatures may lead to increasing levels of forest methane that, in turn, lead to ever-higher temperatures.
“These findings suggest decay in living trees is important to biogeochemists and atmospheric scientists seeking to understand global greenhouse gas budgets and associated climate change,” said Covey.
The other co-authors of the paper, “Elevated Methane Concentrations in Trees of an Upland Forest,” are Stephen Wood, a Ph.D. student at Columbia University, and Robert Warren, former postdoctoral researcher at Yale and now an assistant professor at Buffalo State. The paper can be viewed online.
http://news.yale.edu/2012/08/08/diseased-trees-are-source-climate-changing-gas
Heck, even Ronald Reagan knew trees contributed to air pollution. Are you old enough to remember that? It has been talked about for years that the VOC’s released by trees are pollutants, mainly isoprene and terpene, and that the trees being killed in the west and in BC by bark beetles are releasing methane and CO2 as they decay.
This bit about methane from decay in living trees is something new and bears further study. A quick google didn’t turn up anything more recent (?). It does seem a bit over-hyped.
I interpreted the 10% claim to be merely illustrative and not a true scientific claim because its given that each area of the globe has its own varieties/species of trees and pathogens, and rates of infection/resistance.
I’d put it in the ‘more study needed’ category with everything else.