And statistics. Hah!

Until now, it has been assumed that biogenic methane is formed anaerobically, that is, via micro-organisms and in the absence of oxygen. In this way, acetate or hydrogen and carbon dioxide are transformed into methane; they themselves are created in the anaerobic decomposition of organic materials. The largest anoxic sources of methane are wetlands and rice fields, as well as the digestion of ruminants and termites, waste disposal sites, and the gas produced by sewage treatment plants. According to previous estimates, these sources make up two-thirds of the 600 million tonnes worldwide annual methane production.

Scientists from the Max Planck Institute for Nuclear Physics have now discovered that plants themselves produce methane and emit it into the atmosphere, even in completely normal, oxygen-rich surroundings. The researchers made the surprising discovery during an investigation of which gases are emitted by dead and fresh leaves. Then, in the laboratory and in the wild, the scientists looked at the release of gases from living plants like maize and ryegrass (see image 1). In this investigation, it turned out that living plants let out some 10 to 1000 times more methane than dead plant material. The researchers then were able to show that the rate of methane production grew drastically when the plants were exposed to the sun.

Emphasis added. This discovery is surprising, but the fact that some discovery was made that shreds current climate thinking which is based on exceedingly sparse knowledge of natural systems, and models driven by that exceedingly sparse knowledge, is not surprising. I expect repeated occurrences. The "experts" have been bloviating madly and we all knew that.

It's one thing for a scientist to say that something seems true based on current evidence, but intellectual honesty requires that the primitive state of such evidence be revealed at the same time since this bears heavily on the reliability of the findings. But it is seldom explicitly stated. Other scientists assume this is the case, but policy makers and others often seem to be mesmerized by authority and forget to think. It's poking and hoping, primates playing with sticks and stones. Great fun!

Methane is best known as natural gas, currently an important energy source. Nonetheless, only part of the methane uptake in the atmosphere is due to industrial activities connected to energy production and use. More important for the increase of methane in the atmosphere is the increase in so-called "biogenic" sources, e.g., rice cultivation or domestic ruminants related to the rise in the world's population.

This makes no sense. The number of ruminants on the planet isn't larger than in preindustrial times. Millions of ruminants roamed wild in herds that stretched from horizon to horizon before they were hunted to near extinction and replaced by domestic varieties of the same type. Cattle replaced Bison, etc. Methane is produced in the rumen when they ruminate. It's belches not farts. But modern grain feeding reduces rumination, bypasses it to a great extent, and produces less methane than a natural grass diet. Increasing grain feeding is one of the recommendations of the silly scientists who are working this issue.

Besides, the loss of natural wetlands due to draining swamps seems as great as the creation of artificial swamps for rice cultivation. And the amount of both CO2 and methane emitted by plowing up the prairies is seldom even mentioned though it is a truly huge number. The claims have never seemed to add up, and now we have another major source to consider.

Apparently they made it all up.

Although the scientists have some first indications, it is still unclear what processes are responsible for the formation of methane in plants. The researchers from Heidelberg assume that there is an unknown, hidden reaction mechanism, which current knowledge about plants cannot explain - in other words, a new area of research for biochemistry and plant physiology.

In terms of total amount of production worldwide, the scientists' first guesses are between 60 and 240 million tonnes of methane per year. That means that about 10 to 30 percent of present annual methane production comes from plants. The largest portion of that - about two-thirds - originates from tropical areas, because that is where the most biomass is located. The evidence of direct methane emissions from plants also explains the unexpectedly high methane concentrations over tropical forests, measured only recently via satellite by a research group from the University of Heidelberg.

But why would such a seemingly obvious discovery only come about now, 20 years after hundreds of scientists around the globe started investigating the global methane cycle? "Methane could not really be created that way," says Dr. Frank Keppler. "Until now all the textbooks have said that biogenic methane can only be produced in the absence of oxygen. For that simple reason, nobody looked closely at this."

Nobody looked closely. Nobody thought deeply. Nobody questioned the experts or stepped back and used a little common sense. Typical. Happens all the time. Dead common. Happens to the best of us as well as the worst. It is what we should always expect. Every expert assertion must be understood to be only an informed account of current knowledge, not a true description of reality. The discoveries made about bacteria and fungi in soil (as well as the seas and just about everywhere else - clouds? - who knows) in the past decade have turned that science upside down. I expect all of the biological and geological sciences to continue in turmoil for a long time to come. This isn't a problem, it is progress. The beeb reports the political fallout of this discovery.

The possible implications are set out in Nature by David Lowe of New Zealand's National Institute of Water and Atmospheric Research, who writes, "We now have the spectre that new forests might increase greenhouse warming through methane emissions rather than decrease it by sequestering carbon dioxide."

If this turned out to be true, it would have major implications for the rules of the Kyoto Protocol on climate change, which allows countries and companies to offset emissions from the burning of fossil fuels like coal and oil by funding the planting of new forests or the restoration of deforested areas. . .

It is tempting to conclude from this new study that in some way we have been conned into thinking that trees were great for the planet when it turns out they might be helping to cause global warming.

In fact, of course, trees are neither good nor bad. They are just there, and if they are producing methane now they always have been in natural conditions.

The study highlights, however, the extreme complexity of the relationship between the biological processes of the Earth and the chemistry of our atmosphere - and how much there is yet to discover.

Right. We are pretty much clueless. OK, we have some clues, but that's about it. And right again that "if they are producing methane now they always have been in natural conditions". The idea of trying to blame atmospheric change on swamps, vegetation, termites or ruminants when they have all been here all along is nonsense. Digging up the earth to extract fossil fuel, plant monocultures or bury wastes is another matter, clearly human behaviors that alter the preindustrial balances.

One thought that may be relevant is that our increasingly sophisticated use of nutrients such as nitrogen may have increased the total amount of biomass produced on the planet. OTOH we hear of desertification and reduced biomass production. It isn't clear what is going on or has gone on in the past. The more I learn the less I know. That's OK, I'm down with that, since most of what I know is undoubtedly wrong.

Update:

Those tricky trees!

Trees, particularly those with deep roots, contribute to the Earth's climate much more than scientists thought, according to a new study by biologists and climatologists from the University of California, Berkeley.

While scientists studying global climate change recognize the importance of vegetation in removing carbon dioxide from the atmosphere and in local cooling through transpiration, they have assumed a simple model of plants sucking water out of the soil and spewing water vapor into the atmosphere.

The new study in the Amazonian forest shows that trees use water in a much more complex way: The tap roots transfer rainwater from the surface to reservoirs deep underground and redistribute water upwards after the rains to keep the top layers moist, thereby accentuating both carbon uptake and localized atmospheric cooling during dry periods.

The researchers estimate this effect increases photosynthesis and the evaporation of water from plants, called transpiration, by 40 percent in the dry season, when photosynthesis otherwise would be limited.

"This shifting of water by roots has a physiological effect on the plants, letting them pull more carbon dioxide from the atmosphere as they conduct more photosynthesis," said co-author Todd Dawson, professor of integrative biology at UC Berkeley. "Because this has not been considered until now, people have likely underestimated the amount of carbon taken up by the Amazon and underestimated the impact of Amazonian deforestation on climate." . . .

"Global climate models don't do a very good job of capturing plant effects on how climate might behave," Lee said.

I wonder if the extra carbon taken up by the Amazon offsets the methane released? Maybe if the climate models continue to just leave out stuff and make incorrect assumptions everything will even out? Will they be right as often as a stopped clock?

Update:

An interesting bit from the Nature article about methane is speculation about the impact of this discovery on thinking about paleo-climate.

We also suggest that in pre-industrial times, that is, without anthropogenic emissions, the relative contribution of CH4 to the atmosphere by direct plant emissions may have been even larger than today. This could have far reaching implications for the interpretation of atmospheric CH4 levels and climate signals in the past. For example, variations in total global biomass over glacial cycles18 must contribute to reported differences in atmospheric CH4 mixing ratios between glacial and interglacial periods19. Recent measurements of delta13C values of atmospheric CH4 from ice cores covering the past 2,000 years (ref. 20) provide additional observational support for a prominent role of a plant source in the pre-industrial atmosphere. Unexpectedly enriched delta13C values of around -47permil were shown to persist over the time period 0 to 1200 ad. This cannot be reconciled with a pre-industrial methane budget dominated by isotopically depleted wetland emissions (delta13C - 60permil; ref. 8), as this would lead to atmospheric delta13C values in the region of -54 to -49permil (refs 21, 22). Since direct plant emissions are enriched in 13C compared to wetland emissions (from our measurements we derive a delta13C value of about -50permil based on a 60:40 ratio of C3 and C4 plants), the isotope mass balance for the pre-industrial atmosphere can be closed if plant emissions are included as an important natural CH4 source. Consequently, the role of natural CH4 sources in past climate change, particularly when biospheric productivity changed dramatically, may have to be reconsidered.

And consider the much discussed 'CO2 fertilization effect' in which plant growth accelerates in an atmosphere richer in CO2 while water use declines as leaf stomata don't need to gape open as much to "breathe" CO2. Increased plant growth could also bring increased methane emission.

The effect seems to increase as temperature and sunshine increase. It seems that as the world warms more will be emitted, and also that as the world has warmed since the end of the "little ice age" methane emissions would have increased. This confuses the idea of pre-industrial climate effects. Natural warming would have been contributing to ever increasing warming in a feedback loop.

The effects on policy seem complex. For example, the Methane To Markets initiative which would help developing countries capture and use methane emitted from landfills, coal mines and oil and gas operations may have less effect on climate than previously thought, but be all the more important since it is one of the few ways to reduce emissions, and seems to target the real culprits in post-industrial methane emissions increases.

I suspect we will be thinking and reading about this for some time.

Update:

Transect Points dicusses some implications of the water habits of trees, transfering rainwater from the surface to reservoirs underground and retrieving that water as needed in dryer times. It not only serves the trees needs and accentuates both carbon uptake and localized atmospheric cooling during dry periods, it also serves others in the soil community.

[T]his point concerning nutrition is worth expanding upon. The article indicates that stored water is transferred to the shallower portion of the root system where it must exude into the soil "for keeping the surface soil moist". Soil ion adsorption and plant nutrient exchange processes are moist (vs dry) soil phenomena. Keeping the soil moist just at the root surface would put minimal demand on plant water reserves but have a significant effect on nutrient availability.

It would also support the symbiotic community of soil microorganisms supported by the root system. Arbuscular mycorrhizal fungi and symbiotic soil bacteria are sustained by rhizodeposition, a term which can encompass both liquid root exudates and solid plant cell material. In my experience, root exudates are normally explained as simply an energy or carbon source for the microbes, a carbohydrate quid-pro-quo in exchange for mineral nutrients. It is a fairly thrifty exchange. The water supply component of root exudates highlighted in this new research is an exciting emphasis, at least to your author. Access to steady and stable supply of water, even a parsimonious supply, is ideal for sustaining soil fungi. Resulting beneficial effects, in the form of mycorrhizal hyphae, can extend out from a few centimeters to many meters. Perhaps future observations will be able to determine if the fungi component also plays a role in moistening soil.

See the post for links to supportive material and references to print.

It may be worth adding that mycorrhizal hyphae also transport carbon in the soil, moving the carbs bought from trees and other plants out into the soil, and are made of carbon themselves, and so play a great role in carbon sequestration in the soil. This is in addition to the carbon squirreled away by tree roots.

Update:

The author's of the study offer some perspective.

We first stress that our findings are preliminary with regard to the methane emission strength. Emissions most certainly depend on plant type and environmental conditions and more experiments are certainly necessary to quantify the process under natural conditions. As a first rough estimate of the order of magnitude we have taken the global average methane emissions as representative to provide a rough estimate of its potential effect on climate. These estimates (for details, see below) show that methane emissions by plants may slightly diminish the effect of reforestation programs. However, the climatic benefits gained through carbon sequestration by reforestation far exceed the relatively small negative effect, which may reduce the carbon uptake effect by up to 4 per cent. Thus, the potential for reduction of global warming by planting trees is most definitely positive. The fundamental problem still remaining is the global large-scale anthropogenic burning of fossil fuels. . .

In our study, we have linked global methane emission estimates to plant growth, which is generally quantified as net primary productivity (NPP). On a global basis NPP amounts to ~62 x 1015 g of carbon/yr, which corresponds to an uptake of 227 x 1015 g of CO2/yr. On the emission side, our study suggests annual global methane emissions by plants of 62-236 x 1012 g/yr CH4. Thus, for each kg of CO2 assimilated by a plant roughly 0.25 to 1 to 4 g of CH4 is released. During growth of a new forest, up to 50% of plant tissue is lost again in the short term through decomposition of plant litter of leaves and roots [1]. This then doubles the estimate to 0.5 to 2 g methane emitted per kg of CO2 assimilated and stored in plants for longer periods. Over a 100-year horizon, the global warming potential of methane is ~20 times higher than that of carbon dioxide. Thus, for climate, the benefits gained by reforestation programs would be lessened by between 1 and 4 per cent due to methane emissions from the plants themselves.

I'm not sure about their assumptions. I think more than 50% of the tissue produced in a new forest is ephemeral growth that just recirculates. And this formula seems to mix apples and oranges, trees and all plants.