“…massive deposits of subsea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats…”
Major methane release is almost inevitable
by Michael Marshall / 21 February 2013
We are on the cusp of a tipping point in the climate. If the global climate warms another few tenths of a degree, a large expanse of the Siberian permafrost will start to melt uncontrollably. The result: a significant amount of extra greenhouse gases released into the atmosphere, and a threat – ironically – to the infrastructure that carries natural gas from Russia to Europe. The Arctic is warming faster than the rest of the planet, and climatologists have long warned that this will cause positive feedbacks that will speed up climate change further. The region is home to enormous stores of organic carbon, mostly in the form of permafrost soils and icy clathrates that trap methane – a powerful greenhouse gas that could escape into the atmosphere.
The Siberian permafrost is a particular danger. A large region called the Yedoma could undergo runaway decomposition once it starts to melt, because microbes in the soil would eat the carbon and produce heat, melting more soil and releasing ever more greenhouse gases. In short, the melting of Yedoma is a tipping point: once it starts, there may be no stopping it. For the first time, we have an indication of when this could start happening.Anton Vaks of the University of Oxford in the UK and colleagues have reconstructed the history of the Siberian permafrost going back 500,000 years. We already know how global temperatures have risen and fallen as ice sheets have advanced and retreated, so Vaks’s team’s record of changing permafrost gives an indication of how sensitive it is to changing temperatures.
But there is no direct record of how the permafrost has changed, so Vaks had to find an indirect method. His team visited six caves that run along a south-north line, with the two southernmost ones being under the Gobi desert. Further north, three caves sit beneath a landscape of sporadic patches of permafrost, and the northernmost cave is right at the edge of Siberia’s continuous permafrost zone. The team focused on the 500,000-year history of stalagmites and similar rock formations in the caves. “Stalagmites only grow when water flows into caves,” Vaks says. “It cannot happen when the soil is frozen.” The team used radiometric dating to determine how old the stalagmites were. By building up a record of when they grew, Vaks could figure out when the ground above the caves was frozen and when it wasn’t.
As expected, in most of the caves, stalagmites formed during every warm interglacial period as the patchy permafrost melted overhead. But it took a particularly warm interglacial, from 424,000 and 374,000 years ago, for the stalagmites in the northernmost cave to grow – suggesting the continuous permafrost overhead melted just once in the last 500,000 years. At the time, global temperatures were 1.5 °C warmer than they have been in the last 10,000 years. In other words, today’s permafrost is likely to become vulnerable when we hit 1.5 °C of global warming, says Vaks. “Up until this point, we didn’t have direct evidence of how this happened in past warming periods,” says Ted Schuur of the University of Florida in Gainesville.
It will be very hard to stop the permafrost degrading as a warming of 1.5 °C is not far off. Between 1850 and 2005, global temperatures rose 0.8 °C,according to the 2007 report of the Intergovernmental Panel on Climate Change. Even if humanity stopped emitting greenhouse gases tomorrow, temperatures would rise another 0.2 °C over the next 20 years. That would leave a window of 0.5 °C – but in fact our emissions are increasing. What’s more, new fossil fuel power stations commit us to several decades of emissions.
What are the consequences? The greatest concern, says Tim Lenton of the University of Exeter in the UK, is the regional landscape. Buildings and infrastructure are often built on hard permafrost, and will start subsiding. “Ice roads won’t exist any more.” The increasingly soggy permafrost will also threaten the pipelines that transport Russian gas to Europe. “The maintenance and upkeep of that infrastructure is going to cost a lot more,” says Schuur. As for the methane that could be released into the atmosphere, Schuurestimates that emissions will be equivalent to between 160 and 290 billion tonnes of carbon dioxide. That sounds like a lot, but is little compared to the vast amount humans are likely to emit, says Lenton. “The signal’s going to be swamped by fossil fuel [emissions].” He says the dangers of the permafrost greenhouse gases have been overhyped, particularly as much of the methane will be converted to carbon dioxide by microbes in the soil, leading to a slower warming effect. Schuur agrees with Lenton that the methane emissions are “not a runaway effect but an additional source that is not accounted in current climate models”.
Journal reference: Science, DOI: 10.1126/science.1228729
the METHANE TIME BOMB
by Steve Connor / 23 September 2008
The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists. The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats. Underground stores of methane are important because scientists believe their sudden release has in the past been responsible for rapid increases in global temperatures, dramatic changes to the climate, and even the mass extinction of species. Scientists aboard a research ship that has sailed the entire length of Russia’s northern coast have discovered intense concentrations of methane – sometimes at up to 100 times background levels – over several areas covering thousands of square miles of the Siberian continental shelf.
In the past few days, the researchers have seen areas of sea foaming with gas bubbling up through “methane chimneys” rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a “lid” to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age. They have warned that this is likely to be linked with the rapid warming that the region has experienced in recent years. 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 amount of methane stored beneath the Arctic is calculated to be greater than the total amount of carbon locked up in global coal reserves so there is intense interest in the stability of these deposits as the region warms at a faster rate than other places on earth. Orjan Gustafsson of Stockholm University in Sweden, one of the leaders of the expedition, described the scale of the methane emissions in an email exchange sent from the Russian research ship Jacob Smirnitskyi. “We had a hectic finishing of the sampling programme yesterday and this past night,” said Dr Gustafsson. “An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday, for the first time, we documented a field where the release was so intense that the methane did not have time to dissolve into the seawater but was rising as methane bubbles to the sea surface. These ‘methane chimneys’ were documented on echo sounder and with seismic [instruments].”
At some locations, methane concentrations reached 100 times background levels. These anomalies have been seen in the East Siberian Sea and the Laptev Sea, covering several tens of thousands of square kilometres, amounting to millions of tons of methane, said Dr Gustafsson. “This may be of the same magnitude as presently estimated from the global ocean,” he said. “Nobody knows how many more such areas exist on the extensive East Siberian continental shelves. “The conventional thought has been that the permafrost ‘lid’ on the sub-sea sediments on the Siberian shelf should cap and hold the massive reservoirs of shallow methane deposits in place. The growing evidence for release of methane in this inaccessible region may suggest that the permafrost lid is starting to get perforated and thus leak methane… The permafrost now has small holes. We have found elevated levels of methane above the water surface and even more in the water just below. It is obvious that the source is the seabed.”
The preliminary findings of the International Siberian Shelf Study 2008, being prepared for publication by the American Geophysical Union, are being overseen by Igor Semiletov of the Far-Eastern branch of the Russian Academy of Sciences. Since 1994, he has led about 10 expeditions in the Laptev Sea but during the 1990s he did not detect any elevated levels of methane. However, since 2003 he reported a rising number of methane “hotspots”, which have now been confirmed using more sensitive instruments on board the Jacob Smirnitskyi. Dr Semiletov has suggested several possible reasons why methane is now being released from the Arctic, including the rising volume of relatively warmer water being discharged from Siberia’s rivers due to the melting of the permafrost on the land. The Arctic region as a whole has seen a 4C rise in average temperatures over recent decades and a dramatic decline in the area of the Arctic Ocean covered by summer sea ice. Many scientists fear that the loss of sea ice could accelerate the warming trend because open ocean soaks up more heat from the sun than the reflective surface of an ice-covered sea.
email : orjan.gustafsson [at] itm [dot] su [dot] se
email : igorsmat [at] iarc [dot] uaf [dot] edu
DMT is to ACID, as METHANE is to
The ultimate gas leak that scientists dreaded
by Steve Connor / 23 September 2008
There are two significant facts about methane in terms of global warming. It is about 20 times more potent as a greenhouse gas than carbon dioxide, and there are massive stores of it locked away under the permafrost of the northern hemisphere. Methane is produced naturally by the decay of water-logged vegetation. Over thousands of years it has accumulated under the ground at northern latitudes and has effectively been taken out of circulation by the permafrost acting as an impermeable lid.
What makes methane so potentially dangerous is that its release from under the now-leaking permafrost could accelerate global warming, which in turn would speed the melting of the permafrost and release even more methane. Scientists believe this has happened in the geological past with devastating consequences for the global climate and life. Like carbon dioxide, average methane concentrations in the atmosphere have risen significantly since the Industrial Revolution, increasing from about 700 parts per billion (ppb) in 1800 to about 1,790ppb today. Much of this increase is down to human activities, notably oil and gas exploration, and agriculture.
For the past 10 years, average global methane concentrations have levelled out, probably because of improvements in Russian gas exploration. However, for the first time in more than a decade, scientists recorded an increase in global methane in 2007 and are set to measure a further increase this year. Scientists at the US National Oceanic and Atmospheric Administration (NOAA) have identified the Arctic as a potentially important new source of methane as temperatures in the region increase; it is one of the most rapidly warming places on Earth. “We’re on the look-out for the first sign of a methane release from thawing Arctic permafrost. It’s too soon to tell whether last year’s spike in emissions includes the start of such a trend,” said NOAA’s methane expert Ed Dlugokencky last April.
The good news about methane is that it is quickly degraded in the environment, with an average lifetime of about 12 years, compared to the 100 years of carbon dioxide. The bad news is that we do not understand how the methane stores in the north will behave as the region experiences more extensive thaws. The fear is that the amounts released will make global warming far worse than expected.
email : g.k.westbrook [at] bham [dot] ac [dot] uk
ARCTIC METHANE RESERVE
Hundreds of methane ‘plumes’ discovered
by Steve Connor / 25 September 2008
British scientists have discovered hundreds more methane “plumes” bubbling up from the Arctic seabed, in an area to the west of the Norwegian island of Svalbard. It is the second time in a week that scientists have reported methane emissions from the Arctic. Methane is 20 times more potent than carbon dioxide as a greenhouse gas and the latest findings from two separate teams of scientists suggest it is being released in significant amounts from within the Arctic Circle. On Tuesday, The Independent revealed that scientists on board a Russian research ship had detected vast quantities of methane breaking through the melting permafrost under the seabed of the shallow continental shelf off the Siberian coast.
Yesterday, researchers on board the British research ship the James Clark Ross said they had counted about 250 methane plumes bubbling from the seabed in an area of about 30 square miles in water less than 400 metres (1,300 feet) deep off the west coast of Svalbard. They have also discovered a set of deeper plumes at depths of about 1,200 metres at a second site near by. Analysis of sediments and seawater has confirmed the rising gas is methane, said Professor Graham Westbrook of Birmingham University, the study’s principal investigator. “The discovery of this system is important as its presence provides evidence that methane, which is a greenhouse gas, has been released in this climactically sensitive region since the last ice age,” Professor Westbrook said. An analysis of sediments taken from the seabed show that the gas is coming from methane hydrates – ice-like crystals where molecules of the gas are captured in “cages” made of water molecules, which become unstable as water pressures fall or temperatures rise.
Professor Westbrook said the area surveyed off the west coast of Svalbard was very different to the area being studied by the Russian vessel because the water was much deeper and does not have a layer of permafrost sealing the methane under the seabed. It is likely that methane emissions off Svalbard have been continuous for about 15,000 years – since the last ice age – but as yet no one knows whether recent climactic shifts in the Arctic have begun to accelerate them to a point where they could in themselves exacerbate climate change, he said. “We were very excited when we found these plumes because it was the first evidence there was an active gas system in this part of the world,” Professor Westbrook said after disembarking from the ship, which arrived back in Britain yesterday. “Now we know it’s there we know we have to very seriously consider its effect.”
Antarctic sea ice increases despite warming / 12 September 2008
The amount of sea ice around Antarctica has grown in recent Septembers in what could be an unusual side-effect of global warming, experts say. In the southern hemisphere winter, when emperor penguins huddle together against the biting cold, ice on the sea around Antarctica has been increasing since the late 1970s, perhaps because climate change means shifts in winds, sea currents or snowfall. At the other end of the planet, Arctic sea ice is now close to matching a September 2007 record low at the tail end of the northern summer, in a threat to the hunting lifestyles of indigenous peoples and creatures such as polar bears. “The Antarctic wintertime ice extent increased…at a rate of 0.6% per decade” from 1979 to 2006, says Donald Cavalieri, a senior research scientist at the NASA Goddard Space Flight Center in Maryland. At 19 million square kilometres, it is still slightly below records from the early 1970s of 20 million, he says. Since 1979 however, the average year-round ice extent has risen too.
Some climate sceptics point to the differing trends at the poles as a sign that worries about climate change are exaggerated, but experts say they can explain the development. “What’s happening is not unexpected… Climate modellers predicted a long time ago that the Arctic would warm fastest and the Antarctic would be stable for a long time,” says Ted Maksym, a sea ice specialist at the British Antarctic Survey. The UN Climate Panel says it is at least 90% sure that people are stoking global warming – mainly by burning fossil fuels. But it says each region will react differently. A key difference is that Arctic ice floats on an ocean and is warmed by shifting currents and winds from the south. By contrast, Antarctica is an isolated continent bigger than the US that creates its own deep freeze. “The air temperature in Antarctica has increased very little compared to the Arctic,” says Ola Johannessen, director of the Nansen Environmental and Remote Sensing Center in Bergen, Norway. “The reason is you have a huge ocean surrounding the land.” Cavalieri says some computer models indicate a reduction in the amount of heat coming up from the ocean around Antarctica as one possible explanation for growing ice.
Another theory was that warmer air absorbs more moisture and means more snow and rainfall, he says. That could mean more fresh water at the sea surface around Antarctica – fresh water freezes at a higher temperature than salt water. “There has been a strengthening of the winds that circumnavigate the Antarctic,” says Maksym. That might be linked to a thinning of the ozone layer high above the continent, blamed in turn on human use of chemicals used in refrigerants. In some places, stronger winds might blow ice out to sea to areas where ice would not naturally form. Maksym predicted that global warming would eventually warm the southern oceans, and shrink the sea ice around Antarctica. “A lot of the modellers are predicting the turning point to be right about this time,” he says.
email : emak [at] bas [dot] ac [dot] uk