At the bottom of the Arctic Sea lie vast deposits of methane gas trapped in frozen, icy forms called methane hydrates, and climate scientists would very much prefer that it remains trapped down there. Methane is a powerful greenhouse gas, and some researchers worry that a warming ocean may melt the icy structures, allowing the gas to travel up through the water to the atmosphere, where it could further contribute to global warming. Now, scientists who have been scanning the seas for signs of trouble say they may have found some.
The researchers spotted 250 plumes of methane gas bubbling up through the sea north of Norway. The region where the team found the plumes is being warmed by the West Spitsbergen current, which has warmed by 1 °C over the past 30 years. “Hydrates are stable only within a particular range of temperatures,” says [study coauthor Tim] Minshull. “So if the ocean warms, some of the hydrates will break down and release their methane” [New Scientist]. However, the scientists couldn’t prove that the methane is being released as a direct result of the warming, and say it’s possible there have always been methane seeps like these.
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A new study of the atmosphere of Mars casts doubt on the enticing possibility that methane plumes emanating from the planet are a signature of microbial life. The researchers found that the variations in methane concentration across Mars could only be explained if the methane produced was quickly broken down by unknown forces, before atmospheric currents could distribute the gas evenly around the planet. But methane is the simplest organic molecule, so if something is destroying it, then other, more complex organic molecules could suffer the same fate [New Scientist].
The mystery began in 2003, when scientists first detected plumes of methane coming from the Martian surface; further observations revealed that the hotspots varied with the Martian seasons. Researchers said the methane could come from volcanic activity, but said it could also, theoretically, be the gaseous excretions of bacteria buried deep underground. To probe the mystery, researchers used a model of the Martian climate that accounted for the chemistry of the atmosphere and its wind patterns, and studied whether the planet’s conditions would allow for the isolated bursts of methane that researchers had previously observed.
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It’s not just humans who can take part in combating global warming–cows can play a role, too. Scientists say that the methane belched up by cows is a significant source of the greenhouse gas, and are searching for ways to reduce these burps. The digestive bacteria in the cows’ stomach produces the methane, which is the second-most significant gas (behind carbon dioxide) driving global warming. While methane is much less prevalent in the atmosphere than carbon dioxide, it traps heat 20 times more efficiently than carbon dioxide.
Researchers are examining a variety of tactics, including breeding or genetically engineering cows that belch less, or adjusting the bacterial mix in cows’ stomachs. But altering the cows’ feed has shown the most promise thus far. Since January, cows at 15 farms across Vermont have had their grain feed adjusted to include more plants like alfalfa and flaxseed — substances that, unlike corn or soy, mimic the spring grasses that the animals evolved long ago to eat. As of the last reading in mid-May, the methane output of [one test] herd had dropped 18 percent. Meanwhile, milk production has held its own [The New York Times].
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About 2.7 billion years ago, the primordial seas already hosted the first photosynthetic microbes, the blue-green algae that took in carbon dioxide and released oxygen into the air. But they were outnumbered by methane-producing bacteria called methanogens [that] thrived in nickel-rich seas. The high amounts of methane that this early life pumped into the environment prevented oxygen accumulation in the atmosphere because the methane reacted with any oxygen, creating carbon dioxide and water [Science News], according to one theory. Now, a group of researchers say they’ve found the trigger that allowed oxygen to build up, and therefore allowed for a profusion of oxygen-breathing life.
The secret was the concentrations of the metal nickel, according to the new study, published in Nature. The scientists found that by analysing a type of sedimentary rock known as banded-iron formations they could monitor levels of nickel in the oceans of the early Earth dating as far back as 3.8 billion years ago. They found there was a marked fall in nickel between 2.7 billion and 2.5 billion years ago [The Independent]. That stretch of time correlates with what researchers call the Great Oxidation Event, when oxygen began to take hold in the atmosphere.
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NASA has proposed sending both an orbiter and a robotic explorer to Mars in the next decade to follow up on the recent report that Mars “hotspots” emit plumes of methane gas, which could be produced by either geothermal reactions or by deeply buried bacteria that breathe out methane as a waste product. That exciting phenomenon, which is still being debated by Mars experts, was observed by researchers using ground-based telescopes to measure seasonal fluctuations of gases on the planet. Researchers say closer observations would have a much better chance of determining whether the methane does signal the ultimate prize: extraterrestrial life.
NASA officials sketched out their proposal at a meeting of Mars scientists, but stressed that plans could change. The current idea is to launch the Mars Science Orbiter in 2016 followed by a exobiology lander or rover mission launched during a particularly juicy launch window in 2018 (the best since the Spirit and Opportunity rovers)…. The plan would also follow a natural progression: MSO would map the methane; the lander or rover would go after it with a suite of astrobiological instruments [Nature blog].
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It’s entirely possible that researchers may have detected the first ever evidence of extraterrestrial life. Researchers who spent seven years studying the atmosphere of Mars say they glimpsed discrete plumes of methane gas rising from the surface of the planet in 2003, which could have been produced by bacteria living deep underground. On Earth, a class of bacteria known as methanogens breathes out methane as a waste product [The New York Times].
Before the public could get too excited, the researchers noted that that the biological explanation is just one of two possibilities–there’s also geological processes to consider. The methane could have been produced by geothermal chemical reactions involving water and heat like those in the hot springs of Yellowstone…. [N]o signs of recent volcanism, or even any hot spots, have been spotted on Mars [The New York Times], but ancient volcanic activity could have left methane deposits trapped underground, and puffs of that gas could be routinely released. Finally, the source could be a process known as serpentinisation that occurs at low temperatures and occurs when rocks rich in the minerals olivine and pyroxene react chemically with water, releasing methane [BBC News].
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Three years ago, a controversial study alarmed climate researchers by stating that plants produce methane, a potent greenhouse gas, as part of their normal operations. Those findings went against the standard idea that forests are one of our few buffers against global warming since they absorb and store carbon dioxide; suddenly, scientists began wondering if planting more trees might do more harm than good. But now a new group of researchers says it has refuted the 2006 study, although the scientist who did the original work is not backing down from his claims.
In the new study, to be published in the Proceedings of the Royal Society B, researcher Ellen Nisbet first looked at how that earlier study was conducted, and saw that the earlier researchers had put glass chambers over plants growing in the wild and measured how the mix of gases within the chamber changed. Nisbet says that procedure meant that the plants could have absorbed methane from the soil, instead of creating it themselves. Part of her team’s work involved growing several different varieties of plant, including maize and rice, in media that contained no organic material, so eliminating the chances of methane being formed through decay in soil. They found during these experiments, conducted in closed chambers, that the plants produced no methane at all [BBC News].
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The Arctic plains of Greenland may not seem like a very dynamic place in the autumn, as the cold descends and the topsoil slowly freezes. But researchers who lingered there into the darker months last year discovered that there’s more happening than meets the eye: Methane emissions from the ground spike every fall, just when they were expected to be dropping off to zero. Says lead author Torben Christensen: “Mother Nature is showing us something that is really surprising…. Nobody would expect to have loads of gas seeping out from a frozen environment” [Reuters].
Methane is created when bacteria in the soil feed on rotting organic matter, a decomposition process that requires the warmth of spring and summer. But Christensen hypothesizes that the methane released in the fall is the end of a process that began months earlier. “Most of the methane is produced during the warm summer months, but not all of it is emitted then,” says Christensen. At the Greenland site, for example, only the uppermost 30 to 50 centimeters of soil thaws each summer. In autumn, the ground freezes from above. The top layer of soil freezes and expands, pressurizing the soil beneath, Christensen contends. Because the underlying permafrost is impermeable, any methane that has accumulated in the thawed soil during the summer is squeezed out and forced to the surface [Science News].
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Alarming but preliminary reports of methane gas bubbling up from the Arctic Ocean have raised the specter of precipitous global warming in the minds of some climate scientists.
While aboard a research ship sailing off the coast of Siberia, scientists observed high levels of methane in the water, and then spotted several areas where the gas bubbles were fizzing up from the ocean floor, which contains vast amounts of frozen methane. That was enough to ring the alarm bells: Methane is about 20 times more powerful as a greenhouse gas than carbon dioxide and many scientists fear that its release could accelerate global warming in a giant positive feedback where more atmospheric methane causes higher temperatures, leading to further permafrost melting and the release of yet more methane [The Independent].
While the news seems disquieting, some researchers are expressing some skepticism about the findings, which haven’t yet been published in a peer-reviewed journal. The initial word from a heap of scientists who are focused on sub-sea methane deposits, including a group that videotaped big burps of methane bubbles off Santa Barbara, Calif., a few years ago, is a note of caution about overinterpreting the Arctic bubbling and high gas concentrations as something a) new or b) driven by human-caused global warming [The New York Times, Dot Earth blog].
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Methane, a natural gaseous byproduct of both rotting garbage in landfills and raw sewage, is increasingly regarded as being valuable. Instead of allowing methane to float up into the atmosphere, waste companies are increasingly harnessing it for use as heating gas and as a means to produce electricity [San Francisco Chronicle blog]. It seems to be an alternative energy whose time has come: Methane landfill projects are already online in almost every state, and San Antonio has just signed on to become the first city to harvest methane from its sewage treatment facility.
Harvesting methane serves a two-fold purpose: If it is not captured, the E.P.A. says, landfill methane becomes a greenhouse gas at least 20 times more potent than carbon dioxide, the principal greenhouse gas, when it rises into the atmosphere. The agency estimates that landfills account for 25 percent of all methane releases linked to human activity. As a result, capturing methane at former and active landfills is a global housekeeping benefit as well as an important alternative energy niche [The New York Times].
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The Earth was an inhospitable place 635 million years ago, when ice sheets that extended to the equator. Scientists have long wondered how the planet rebounded from that icy era, known as “Snowball Earth.”
Now a new study suggests that a stream of methane gas escaping from the ice brought the planet to a climate tipping point and transformed it into a lush, tropical world, in what researchers called one of the most severe climate change events recorded in Earth history [Nature, subscription required].
Paleoclimatology has become a hot field, as researchers believe that the planet’s dramatic prehistoric climate shifts can help predict the effects of present-day global warming. Since methane figures into one of the most ominous global warming scenarios, this latest study is being eagerly scrutinized for clues to our planet’s fate.
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