The West Virginia coal mining accident yesterday killed at least 25, and hope is starting to fade for finding the four missing miners alive. It’s the deadliest mining accident in the United States in more than a quarter-century.
A methane explosion appears to be the cause. Normally when DISCOVER covers methane scares, it has to do with the potent greenhouse gas leaking from permafrost or the ocean. But for coal miners, methane represents a more clear and present danger: Underground mines can fill up with the flammable gas, and a stray spark can light it and cause an explosion. As a result, mines are required to have giant fans that blow methane out of the working area.
Methane not only appears to have caused the accident, it also held up the rescue effort. Operations had to be suspended because of a build-up of methane in the mine. It’s hoped that they can resume later today — but it will require drilling about 1,000 feet, through two coal seams, to get to where the men might have been able to find shelter [NPR].
Methane is ubiquitous in coal mines. The gas, like coal, is a molecule made of hydrogen and carbon, and it is produced from the same raw material as coal, ancient piles of biological material, by the same processes. Much of the natural gas sold in the United States is drawn from coal seams. In undisturbed coal deposits, the methane is kept loosely attached to the coal molecules by compression; when the area is opened up by miners, the pressure is reduced and the methane bubbles out [The New York Times].
Behind the ongoing back-and-forth fights over climate change that usually focus on carbon, there has lingered the threat of the powerful greenhouse gas methane being released into the atmosphere and causing even worse trouble. In August we reported on a study that noted methane bubbling up from the seafloor near islands north of Norway, giving scientists a scare. This week in Science, another team reports seeing the same thing during thousands of observations of the East Siberian Arctic Shelf on Russia’s north coast, which is even more worrisome because it’s a huge methane deposit.
The shelf, which covers about 800,000 square miles, was exposed during the last ice age. When the region was above sea level, tundra vegetation pulled carbon dioxide from the air as plants grew. That organic material, much of which didn’t decompose in the frigid Arctic, accumulated in the soil and is the source of modern methane [Science News]. Now underwater, it’s covered by a layer of permafrost. But that permafrost seems to be becoming unstable, thanks to the fact that the water on top of it is warmer than the air it was exposed to back when it was on dry land.
As the count of known planets in distant star systems continues to grow (the number now exceeds 400), so too does the number of ways we have to learn about them. Reporting in Nature this week, a team of astronomers say they have measured the makeup of an exoplanet‘s atmosphere using an Earth-based telescope for the first time.
Mark Swain’s team directed NASA’s Infrared Telescope Facility toward HD 189733 b, a planet 63 light years away, discovered back in 2005. HD 189733 b was already known from space-borne observations to harbor several specific molecules in its atmosphere: water, methane, carbon dioxide and carbon monoxide [Scientific American]. Swain’s analysis confirmed those previous findings using spectrography, in which the light from an object is broken down into its component wavelengths, allowing the identification of atoms or molecules by their unique emission or absorption properties [Scientific American]. Swain’s team also turned up something else—a spike in emissions at a very particular wavelength of light, 3.3 microns, that the earlier observations didn’t detect and that Swain’s team can’t explain–at least not yet.
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.
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.
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].
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.
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].
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].
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].