View Full Version : Hints of methane's renewed rise
08-31-2008, 04:30 AM
One of the biggest problems awaiting us is the methane which is still sequestered in the Siberian permafrost soils. Like the ice at the top of our planet the permafrost is melting thus releasing the methane.
Methane output had stopped rising for a time but it's emissions are up and a lot seems to come from these soils.
The first few articles are from thread at the old board.
08-31-2008, 04:31 AM
Levels of the greenhouse gas methane in the atmosphere seem to be rising having remained stable for nearly 10 years.
Data from the National Oceanographic and Atmospheric Administration (Noaa) in the US suggest concentrations rose by about 0.5% between 2006 and 2007.
The rise could reflect melting of permafrost, increased industrialisation in Asia or drying of tropical wetlands.
The rise in carbon dioxide levels was significantly higher than the average annual increase for the last 30 years.
Noaa figures show CO2 concentrations rising by 2.4 parts per million (ppm) from 2006 to 2007. By comparison, the average annual increase between 1979 and 2007 was 1.65ppm.
Concentrations now stand at 384 ppm, compared to about 280 ppm before the era of human industrialisation began.
The rise in CO2 is not exceptional compared with the previous few years, but does add more evidence that concentrations are rising faster than they were a decade or so ago.
The methane figure is more interesting, and potentially of more concern.
Concentrations have been more or less stable since about 1999 following years of rapid increases. Industrial reform in the former Soviet bloc, changes to rice farming methods and the capture of methane from landfill sites all contributed to the levelling off.
But the 2007 figure indicates that levels may be on the rise again.
"Looking at the curve, there is a sign that methane is showing some increase," commented Geir Braathen, senior scientific officer with the World Meteorological Organization, who was not involved in the Noaa publication.
"But the mechanism behind that would be uncertain; and it's too early to say if this is the start of a new increase or not.
"We will need several years of increase before we can state that there is a rising trend."
Methane concentrations have shown small rises and falls during the years of stability, but rises have been associated with El Nino conditions which are known to induce more wildfires.
Currently, the world is experiencing La Nina conditions, the opposite of El Nino.
A sustained rise could be due to several reasons. Asia's spectacular industrialisation, reversion to older rice farming techniques, and a drying out of tropical wetlands would all be candidates if the rising trend is confirmed.
Equally possible would be the release of methane from frozen zones of the world, notably the Arctic permafrost, as they warm.
Methane is the second most important gas causing man-made climate change. Each molecule causes about 25 times more warming than a molecule of CO2, but it survives for shorter times in the atmosphere before being broken down.
08-31-2008, 04:32 AM
Siberian permafrost melting
Published: 15:48 EST, August 11, 2005
Russian scientists said the western Siberian sub-Arctic region -- a peat bog the size of France and Germany -- has begun to thaw.
The scientists warned the melting permafrost could unleash billions of tons of greenhouse gases into the atmosphere, the Daily Telegraph reported Thursday.
The 360,000 square miles of western Siberia may turn into a watery landscape of shallow lakes and it could release huge quantities of methane trapped in the frozen peat, according to researchers Sergei Kirpotin, a botanist from Tomsk State University in Russia, and Judith Marquand from Oxford University.
Kirpotin told New Scientist the western Siberian sub-Arctic region had begun to melt in the last three or four years in an "ecological landslide that is probably irreversible and undoubtedly connected to climatic warming.
08-31-2008, 04:33 AM
Warming climate is taking its toll on subterranean ice
Daniel Fortier spends his summers studying the permafrost on Bylot Island, high in the eastern Canadian Arctic. While hiking there early in the 1999 field season, he distinctly heard the sound of running water yet saw no streams nearby. "I thought to myself, 'Where is this sound coming from?'" says Fortier. "So, like a good researcher, I started to dig."
Excavating the soil, known as permafrost because its temperature is below 0°C year-round, Fortier tapped into a torrent-filled tunnel a meter or so below the surface. By tracking the water course uphill, he found its source: Large volumes of snowmelt had flowed into open fissures in the ground and had then melted a passage through a network of subterranean ice wedges that had formed over millennia (SN: 5/17/03, p. 314: http://www.sciencenews.org/articles/20030517/bob10.asp).
Eventually, the surprising tunnel grew so wide that its roof caved in, creating a gully that erosion then widened, says Fortier, a geomorphologist at the University of Alaska in Fairbanks. By the end of the summer, that gully was about 250 m long and 4 m wide. During the next 4 years, the network of underground tunnels at the site turned into a 750-m-long system of gullies that drained an area about the size of four soccer fields. Since then, Fortier and his colleagues have observed the same phenomenon at other sites on Bylot Island.
Several teams of scientists had previously described similar networks of gullies at various sites in the Arctic, but those highly eroded features had been deemed as much as several thousand years old. "No one had ever seen one of these things forming," says Fortier. "We were in the right place at the right time."
Researchers are observing many new phenomena in the Arctic—most of them related to the world's changing climate. Globally, 11 of the 12 years from 1995 to 2006 are among the dozen warmest since the mid-1800s, scientists of the Intergovernmental Panel on Climate Change reported last month (SN: 2/10/07, p. 83: Available to subscribers at http://www.sciencenews.org/articles/20070210/fob1.asp). Average temperatures worldwide have risen about 0.7°C in the past 100 years, but those in the Arctic have risen even more. In high-latitude portions of Alaska and western Canada, average summer temperatures have increased by about 1.4°C just since 1961 (SN: 11/12/05, p. 312: Available to subscribers at http://www.sciencenews.org/articles/20051112/bob9.asp).
Those warmer air temperatures are significantly boosting soil temperatures in many regions, new studies show. Because the average annual temperature at many Arctic sites sits at or just below water's freezing point, even a small increase in local warming can have big consequences. Besides rendering underground ice wedges more susceptible to melting, the hike in temperatures threatens near-surface permafrost that has been in place since the height of the last ice age, about 25,000 years ago. Ecological changes, such as shifts in the patterns and timing of forest fires, further endanger near-surface permafrost. But researchers are still working out whether the permafrost will disappear over decades or millennia.
Permafrost serves as a stable foundation for much of the Arctic's infrastructure, including pipelines, roads, buildings, and bridges. In many areas, that frozen ground also contains huge amounts of organic material, which could readily decompose and send carbon dioxide, a greenhouse gas, into the atmosphere if the permafrost thaws (SN: 11/12/05, p. 312: Available to subscribers at http://www.sciencenews.org/articles/20051112/bob9.asp).
When most people think of permafrost, they envision the coldest Arctic landscapes, where layers of ground hundreds of meters thick have remained deep-frozen since the last ice age, maybe even longer. However, permafrost need not be either long-lived or icy. Geologists consider any soil or rock that's been colder than 0°C for more than 2 years to be permafrost.
Permafrost lies beneath as much as 25 percent of the land area of the Northern Hemisphere. Although much of the frozen ground occurs in high-latitude regions, the rocky summits of many high-altitude peaks in temperate and tropical latitudes also consist of permafrost, says Margareta Johansson, a physical geographer at the Abisko Scientific Research Station in Abisko, Sweden. She and her colleagues have conducted long-term permafrost studies in the region surrounding Abisko, which is about 200 kilometers north of the Arctic Circle. They reviewed their findings in the June 2006 Ambio.
The presence or absence of permafrost at any particular spot depends on the balance between geothermal heat making its way up from Earth's interior and the average annual air temperature at the site, says Johansson. "The lower a site's average air temperature is, the more heat the air pulls from the ground," she notes, leaving the soil colder and the permafrost thicker.
The slope of the terrain has a significant effect as well. South-facing slopes usually receive more direct sunlight and therefore are warmer than flat terrain would be. By contrast, northern slopes spend much of the day in shade, so soil temperatures there are chillier than the region's average and more conducive to the formation of permafrost.
Although permafrost can form in any climate where the average annual air temperature is below freezing, it doesn't normally occur or persist widely until temperatures are substantially lower, says Johansson. When an area's average temperature lies between 0°C and –1.5°C, permafrost is patchy and typically underlies no more than 10 percent of the region. At sites with average air temperatures below –6°C, few spots if any are free of permafrost.
"The amount of snowfall at a site significantly affects the permafrost there, but in a counterintuitive way," says Johansson. When snow forms a thick blanket that lasts all winter, it insulates the ground from the most frigid air of the year. Near Abisko, which receives only about 30 centimeters of snow each year, the permafrost is about 16 meters thick, the deepest in the region, she notes. At similarly cold sites that receive as little as 1 m of snowfall each winter, permafrost is patchier and only a few meters thick.
In experiments at several sites in the Abisko region, Johansson and her colleagues piled up extra snow at some sites, artificially doubling or tripling the snowfall that the spot would normally receive over a winter. As a result, average ground temperatures rose as much as 2.2°C. That large a change can melt underlying permafrost.
Scientists elsewhere have noted that winter snow cover can keep the average ground temperature as much as 10°C higher than the average air temperature, Johansson notes.
It's often difficult for scientists to accurately predict how vegetation will affect ground temperatures, says Johansson. Evergreen trees and shrubs cast shadows that cool the ground during the summer. However, the vegetation forms a windbreak that tends to trap snow in winter, creating drifts that warm the soil. Computer simulations suggest that shrubby sites in northern Alaska accumulate as much as 20 percent more snow than bare ones do, and scientists have found that the soil in shrubby areas is about 2°C warmer than soil in shrub free spots nearby.
Fire and ice
The wildfires that intermittently ravage Arctic forests can exact a harsh toll from permafrost. It's not the heat of the conflagration that does the damage but the changes that take place after the fire dies down.
A severe fire strips away the foliage that shades the forest floor. The resulting increase in sunlight reaching the ground boosts soil temperature, says Eric S. Kasischke, a fire ecologist at the University of Maryland, College Park.
An even greater warming effect stems from the fire's consumption of the limbs, twigs, needles, and leaves that had fallen to the ground and insulated it. Unlike a blanket of snow, forest litter insulates the ground year-round. It keeps the ground warmer in winter and cooler in summer. On balance, the insulation favors permafrost formation and retention.
Consider what happens in a black spruce forest, the type that makes up more than half of North America's boreal forests. Scientists have gathered data at more than 200 central-Alaska sites that had recently suffered wildfires. On average, between 50 and 60 percent of the forest-floor litter goes up in smoke during a fire, Kasischke and his colleagues reported at a meeting of the American Geophysical Union in San Francisco last December.
After a fire has destroyed so much litter, a much thicker surface layer of soil thaws each summer, says Kasischke. During the growing season, seedlings quickly become established in that thawed soil. Then, as trees mature, they shade the ground more effectively and drop limbs and needles to reestablish the forest floor's veneer of insulation.
Computer models suggest that permafrost begins to recover when organic material on the forest floor accumulates to a depth of at least 9 cm. In a region where trees grow slowly, that could take decades.
The interval between wildfires in any particular patch of boreal forest ranges between 30 and 300 years, Kasischke notes. But, the postfire recuperation of a forest's permafrost isn't a sure bet. Because today's climate in a region may be substantially warmer than it was the last time fire swept through, conditions may not be conducive to permafrost recovery.
When the centuries-long cold spell called the Little Ice Age ended about 150 years ago, glaciers and permafrost reached their maximum extent of the past few millennia. Deep remnants of that permafrost will probably persist for millennia to come. However, in a world that's warming, it's only a matter of time until much of that ice melts. Most permafrost loss will take place at shallow depths, where it will have the greatest effect on ecosystems and people.
In many regions, permafrost temperatures, like air temperatures, have been climbing steadily for decades, says Sergei Marchenko, a permafrost researcher at the University of Alaska in Fairbanks. Data gathered in field studies since the early 1970s indicate that permafrost temperatures in the Altai region of Mongolia and the Tian Shan mountains of central Asia have risen as much as 0.2°C per decade, he notes. Similar rates of warming have been observed on the Tibetan Plateau since 1985.
In the Tian Shan mountains, the thickness of the seasonally thawed layer has increased 23 percent since the early 1970s. It's now 5 m thick, says Marchenko. Climate simulations suggest that since the end of the Little Ice Age, the lowest altitude at which permafrost could persist has climbed about 200 m. During that time, about 16 percent of the region's permafrost would have disappeared, according to the model that Marchenko and his University of Alaska colleague Vladimir Romanovsky described at the American Geophysical Union meeting.
Measurements taken inside three boreholes, each at least 400 m deep, at a mine in the barren terrain of northern Quebec also chronicle modern-day warming, says Christian Chouinard, a paleoclimatologist at McGill University in Montreal. The data suggest that surface soil has heated up about 2.75°C in the past 150 years, he and his colleagues reported at the meeting.
A slight cooling trend in the region from the 1940s to the early 1990s has since been replaced by extremely rapid warming—more than 1°C in the past 15 years or so, the researchers note.
Permafrost can be quick to warm to its melting point but then slow to melt. The energy needed to melt a block of ice at 0°C is about 160 times the amount that's needed to raise its temperature from –1°C to 0°C, says Sharon L. Smith, a permafrost researcher at the Geological Survey of Canada in Ottawa.
Data gathered throughout Canada show that permafrost in the coldest regions of the country is steadily warming, as are soils in areas free of permafrost. However, in the areas where permafrost sits at its melting point, ground temperatures aren't changing significantly. Much of the air's thermal energy goes into melting the permafrost rather than into warming it.
About 42 percent of Canada's land area, or about 4 million square kilometers, overlies permafrost, says Smith. In about half that area, the permafrost is patchy and thin, with a temperature above –2°C. If many scientists' climate-warming scenarios come to pass, Smith says, "permafrost in those regions could ultimately disappear."
When it will disappear is another issue. Research published in 2005 sparked a major debate. In that report, climate scientists David M. Lawrence of the National Center for Atmospheric Research in Boulder, Colo., and Andrew G. Slater of the University of Colorado at Boulder suggested that climate warming will wipe out more than 90 percent of the world's near-surface permafrost by the year 2100.
That dramatic claim is almost certainly wrong, says Christopher Burn, a permafrost researcher at Carleton University in Ottawa. Burn says that although he doesn't dispute the predictions of climate warming, he does question Lawrence and Slater's predictions concerning the pace and extent of the permafrost's demise.
Burn says that the Colorado scientists' estimate requires that permafrost melt almost instantaneously. Instead, the time lag between the climate warming and the permafrost melting will probably be hundreds of years, he suggests.
Lawrence agrees that the computer model that he and Slater used for their study had some limitations—for instance, it included only the top 3.4 m of the ground and didn't account for conditions associated with some soil types. The pair has now modified its model to look 50 m into the ground, says Lawrence. Preliminary results suggest that this deeper permafrost will indeed last longer than they'd previously predicted—but only a couple of decades longer at most—he reports.
Nevertheless, Burn says that the model doesn't take into account the cooling effect of permafrost that lies deeper. For example, permafrost in Alaska and western Canada extends as much as 600 m into the ground, and in Siberia it's more than 1.5 km thick. "The persistence of permafrost increases with its thickness," Burn adds. So, deep soil will stay cold for millennia, thereby putting brakes on the warming of the higher layers.
Whatever the rate of permafrost loss, Earth's rapidly warming climate will continue to gnaw at the long-frozen soil that serves as the bedrock of the Arctic. The carbon dioxide that will probably be released in the process will only tend to accelerate the permafrost's disappearance.
08-31-2008, 04:33 AM
Over 10% of the earth’s surface is covered in tundra, a thin layer of slow-growing plant matter (dwarf shrubs, grasses, mosses, lichens, etc.), which covers a frozen bog of organic matter called permafrost.
Due to very short growing seasons and very low temperatures, the expansive areas of tundra in the frigid north of Russia, Alaska, Canada, etc., can only support an incredibly slow breakdown of organic material. Essentially, permafrost stores thousands of years of plant and animal organic matter. It is a vast carbon sink. Or, at least, it was….
If you’ve ever heard the terms ‘runaway effects’ or ‘feedback loops’ in connection with climate change - this is one of the most significant.
As the world warms, the permafrost melts - speeding up the ‘metabolism’ of these regions. This allows micro-organisms that normally struggle to function at lower temperatures to suddenly begin working at an accelerated rate - subsequently releasing incomprehensible amounts of CO2, and, even worse, methane, into the atmosphere. Methane is "over 20 times more effective in trapping heat in the atmosphere than carbon dioxide (CO2) over a 100-year period" (USEPA). Currently, scientists state our atmosphere contains two and a half times as much methane as it did in pre-industrial times, and with millions of square miles of permafrost beginning to melt, this looks set to increase dramatically.
08-31-2008, 04:34 AM
Methane rise points to wetlands
Higher atmospheric levels of the greenhouse gas methane noted last year are probably related to emissions from wetlands, especially around the Arctic.
Scientists have found indications that extra amounts of the gas in the Arctic region are of biological origin.
Global levels of methane had been roughly stable for almost a decade.
Rising levels in the Arctic could mean that some of the methane stored away in permafrost is being released, which would have major climatic implications.
The gas is about 25 times more potent than carbon dioxide as a greenhouse gas, though it survives for a shorter time in the atmosphere before being broken down by natural chemical processes.
Indications that methane levels might be rising after almost a decade of stability came last month, when the US National Oceanic and Atmospheric Administration (Noaa) released a preliminary analysis of readings taken at monitoring stations worldwide.
Noaa suggested that 2007 had seen a global rise of about 0.5%.
Some stations around the Arctic showed rises of more than double that amount.
One is the station at Mount Zeppelin in Svalbard, north of Scandinavia.
In addition to the long-term monitoring carried out there by Norway and Sweden, a British team has recently started gathering samples and analysing them in a way that could reveal where the methane is coming from.
Methane produced by bacteria contains a high proportion of molecules with the lighter form (isotope) of carbon, carbon-12, rather than the heavier form, carbon-13.
"Anything where bacteria form methane, you get depletion in C-13 because methanogens (the bacteria) preferentially use C-12," said Rebecca Fisher from Royal Holloway, University of London, who has been running the Svalbard experiments.
"The results we have so far imply a predominantly biogenic source," she told BBC News.
The researchers also match methane levels with wind direction, so they can see where the gas is being produced. This analysis also implies a source in the Arctic regions, rather than one further afield such as the additional output from Asia's rapid industrialisation.
Warm and wet
Ed Dlugokencky, the scientist at Noaa's Earth System Research Laboratory (ESRL) who collates and analyses data from atmospheric monitoring stations, agrees that the 2007 rise has a biological cause.
"We're pretty sure it's not biomass burning; and I think 2007 is probably down to wetland emissions," he said.
"In boreal regions it was warmer and wetter than usual, and microbes there produce methane faster at higher temperatures."
Dr Dlugokencky also suggested that the drastic reduction in summer sea ice around the Arctic between 2006 and 2007 could have increased release of methane from seawater into the atmosphere.
A further possibility is that the gas is being released in increasing amounts from
permafrost as temperatures rise.
Researchers will be keeping a close eye on this year's data which will indicate whether 2007 was just a blip or the beginning of a sustained rise.
Methane concentrations had been more or less stable since about 1999 following years of rapid increases, with industrial reform in the former Soviet bloc, changes to rice farming methods and the capture of methane from landfill sites all contributing to the levelling off.
In the recent past, concentrations have risen during El Nino events, whereas the world is currently amid the opposite climatic pattern, La Nina.
An upturn in methane concentrations emissions could have significant implications for the Earth's climatic future.
A sustained release from Arctic regions or tropical wetlands could drive a feedback mechanism, whereby higher temperatures liberate more of the greenhouse gas which in turn forces temperatures still higher.
A particularly pertinent question is whether methane is being released from hydrates on the ocean floor.
These solids are formed from water and methane under high pressure, and may begin to give off methane as water temperatures rise.
The amount of the gas held in oceanic hydrates is thought to be larger than the Earth's remaining reserves of natural gas.
In collaboration with other British institutions, Dr Fisher's team will begin work this summer sampling water near hydrate deposits to look for indications of gas emerging.
08-31-2008, 04:34 AM
Permafrost Threatened by Rapid Retreat of Arctic Sea Ice, NCAR Study Finds
juni 10, 2008
BOULDER—The rate of climate warming over northern Alaska, Canada, and Russia could more than triple during periods of rapid sea ice loss, according to a new study led by the National Center for Atmospheric Research (NCAR). The findings raise concerns about the thawing of permafrost, or permanently frozen soil, and the potential consequences for sensitive ecosystems, human infrastructure, and the release of additional greenhouse gases.
"Our study suggests that, if sea-ice continues to contract rapidly over the next several years, Arctic land warming and permafrost thaw are likely to accelerate," says lead author David Lawrence of NCAR.
The study, by scientists from NCAR and the National Snow and Ice Data Center, will be published Friday in Geophysical Research Letters. It was funded by the U.S. Department of Energy and by the National Science Foundation, NCAR's sponsor.
The research was spurred in part by events last summer, when the extent of Arctic sea ice shrank to more than 30 percent below average, setting a modern-day record. From August to October last year, air temperatures over land in the western Arctic were also unusually warm, reaching more than 4 degree Fahrenheit (2 degrees Celsius) above the 1978-2006 average and raising the question of whether or not the unusually low sea-ice extent and warm land temperatures were related.
To investigate this question, Lawrence and his colleagues analyzed climate change simulations generated by the NCAR-based Community Climate System Model. Previous analysis of these simulations suggested that a sustained period of rapid ice loss lasting roughly 5 to 10 years can occur when the ice thins enough. During such an event, the model revealed, the minimum sea-ice extent can drop by an area greater than the size of Alaska and Colorado combined.
The team found that during episodes of rapid sea-ice loss, the rate of Arctic land warming is 3.5 times greater than the average 21st century warming rates predicted in global climate models. While this warming is largest over the ocean, the simulations suggest that it can penetrate as far as 900 miles inland. The simulations also indicate that the warming acceleration during such events is especially pronounced in autumn. The decade during which a rapid sea-ice loss event occurs could see autumn temperatures warm by as much as 9 degrees F (5 degrees C) along the Arctic coasts of Russia, Alaska, and Canada.
Lawrence and his colleagues then used the model to study the influence of accelerated warming on permafrost and found that in areas where permafrost is already at risk, such as central Alaska, a period of abrupt sea-ice loss could lead to rapid soil thaw. This situation, when summer thaw extends more deeply than the next winter’s freeze, can lead to a talik, which is a layer of permanently unfrozen soil sandwiched between the seasonally frozen layer above and the perennially frozen layer below. A talik allows heat to build more quickly in the soil, hastening the long-term thaw of permafrost.
Potential impacts on greenhouse gase
Arctic soils are believed to hold 30 percent or more of all the carbon stored in soils worldwide. Although researchers are uncertain what will happen to this carbon as soils warm and permafrost thaws, one possibility is that the thaw will initiate significant additional emissions of carbon dioxide or the more potent greenhouse gas, methane.
About a quarter of the Northern Hemisphere's land contains permafrost, defined as soil that remains below 32 degrees F (0 degrees C) for at least two years. Recent warming has degraded large sections of permafrost, with pockets of soil collapsing as the ice within it melts. The results include buckled highways, destabilized houses, and "drunken forests" of trees that lean at wild angles.
"An important unresolved question is how the delicate balance of life in the Arctic will respond to such a rapid warming," Lawrence says. "Will we see, for example, accelerated coastal erosion, or increased methane emissions, or faster shrub encroachment into tundra regions if sea ice continues to retreat rapidly?"
The study sheds light on how interconnected the Arctic system is, says co-author Andrew Slater, a scientist at the National Snow and Ice Data Center (NSIDC). "The loss of sea ice can trigger widespread changes that would be felt across the region."
About the article
Authors: David Lawrence, Andrew Slater, Robert Tomas, Marika Holland, and Clara Deser
Publication: Geophysical Research Letters, June 13, 2008
08-31-2008, 04:36 AM
Methane leaks from seabed
Web posted at: 8/31/2008 8:11:53
Source ::: AFP
STOCKHOLM • Methane, a potent greenhouse gas, is leaking from the permafrost under the Siberian seabed, a researcher on an international expedition in the region told Swedish daily Dagens Nyheter yesterday.
"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," Oerjan Gustafsson, the Swedish leader of the International Siberian Shelf Study, told the newspaper. The tests were carried out in the Laptev and east Siberian seas and used much more precise measuring equipment than previous studies, he said.
Methane is more than 20 times more efficient than carbon dioxide in trapping solar heat.
Scientists fear that global warming may cause Siberia's permafrost to thaw and thereby release vast amounts of methane into the atmosphere. The effects of global warming are already most visible in the Arctic region.
08-31-2008, 04:49 AM
I took some comparisons of CO2 and CH4's effect from the comments (#27 and #35) from this thread:
A sandbox 101 question: What is it that makes methane and others “much more powerful” greenhouse gases? Is it because their internal makeup allows considerably more IR absorption, molecule for molecule? Or is it because they absorb in bands like the window that are “virgin territories”? For example if we had no GHG in the atmosphere, then added say 50ppm of both CO2 and CH4, which gas would contribute more toward warming? Or is it related to the relative lifetime of the various gases? Or some combination?
[Response: All of the above. Different bands are differently absorbed depending on what the resonance is (vibrational, stretching etc.) and that depends somewhat on the strength of the bonds (which is obviously molecule specific). Concentration matters a lot - absorption is linear at very low concentrations and flattens out to logarithmic at higher values. And overlap is really important. If a molecule absorbs in the atmospheric window region, it is much more important than one that overlaps with water vapour. - gavin]
”There is, however, a widespread misconception that methane is in some sense an intrinsically better greenhouse gas than CO2. A few simple calculations will serve to clarify the true state of affairs….
The common statement that methane is, molecule for molecule, a better greenhouse gas than CO2 is true only for situations like the present where methane is present in far lower concentrations
than CO2. In this situation, the greater power of a molecule of CH4 to reduce the OLR results simply from the fact that the greenhouse effect of both CH4 and CO2 are approximately logarithmic in concentration. Reading from Fig. 4.35, we see that for methane concentrations of around 1ppmv, each doubling of methane reduces OLR by about 2W/m2. On the other hand, for CO2 concentrations near 300 ppmv, each doubling of CO2 reduces the OLR by about 6 W/m2. Hence,
to achieve the same OLR reduction as a doubling of CO2 one needs three doublings of methane, but since methane starts from a concentration of only 1ppmv, this only takes the concentration to
8ppmv, and requires only 7/300 as many molecules to bring about as was needed to achieve the same reduction using a doubling of CO2. Equivalently, we can say that adding 1ppmv of methane yields as much reduction of OLR as adding 75ppmv of CO2…..
If methane were the most abundant long-lived greenhouse gas in
our atmosphere, and CO2 were present only in very small concentrations, we would say instead that CO2 is, molecule for molecule, the better greenhouse gas. “
08-31-2008, 05:28 AM
I wonder if there is any method for actually using the methane from thawing permafrost tundra for producing energy. It would be the same principle as getting energy from cow manure, which they have been doing for years.
08-31-2008, 05:54 AM
I wonder if there is any method for actually using the methane from thawing permafrost tundra for producing energy. It would be the same principle as getting energy from cow manure, which they have been doing for years.
The scale is problematic. Collecting cow farts is a lot easier when they are close together in a shed then collecting the all that gas seeping from the ground.
We could hardly cover up Siberia or the sea bed so there's no way to stop it, although i'm open to suggestions.
08-31-2008, 09:38 AM
Cow farts? I thought cows burped up most of their methane gas.
09-06-2008, 02:54 AM
Here's a bit from:
Shrinking Arctic Ocean sea ice signals climate change
Until now, the loss of Arctic ice has had far less effect on large-scale ocean circulation patterns than researchers once expected, Rigor says. But increasing amounts of open water in the Arctic absorb heat, which forestalls the onset of the fall and winter freeze.
The influence of that warming could have geographically far-reaching effects. In June, scientists with the National Center for Atmospheric Research in Boulder, Colo., and the Snow and Ice Data Center calculated that during five- to 10-year periods of rapid sea-ice loss, autumn temperatures could rise by up to 9 degrees F along the coastlines that ring the Arctic Ocean. That warming would prolong the melt season for permafrost, increasing the rate at which it releases enormous amounts of stored carbon as greenhouse gases carbon dioxide or methane.
09-24-2008, 12:56 PM
Researchers found massive stores of sub-sea methane in several areas across thousands of square miles of the Siberian continental shelf and observed the gas bubbling up from the sea floor through "chimneys", according to reports.
One of the expedition leaders, Orjan Gustafsson, of Stockholm University in Sweden, said researchers had found "an extensive area of intense methane release".
Arctic 'methane chimneys' raise fears of runaway climate change
Researchers say evidence suggests that the frozen seabed is perforated and is starting to leak methane, but other scientists urge caution
09-26-2008, 10:08 PM
Greenhouse gas emissions shock scientists
Carbon dioxide output is rising rather than falling, despite efforts to curb it. 'It's scary,' one researcher says.[/color]
From Times Wire Services
September 26, 2008
WASHINGTON -- The world pumped up emissions of the chief human-produced global warming gas last year, setting a course that could push beyond leading scientists' projected worst-case scenario, international researchers said Thursday.
The new numbers, which some scientists called "scary," were a surprise because experts thought an economic downturn would slow energy use. Instead, carbon dioxide output rose 3% from 2006 to 2007.
That amount exceeds the most dire outlook for emissions from burning coal and oil and related activities as projected by a Nobel Prize-winning group of international scientists in 2007.
Meanwhile, forests and oceans, which suck up carbon dioxide, are doing so at lower rates, scientists said. If those trends continue, the world will be on track for the highest predicted rises in temperature and sea level.
The U.N.'s Intergovernmental Panel on Climate Change has warned that an increase of between 3.2 and 9.7 degrees Fahrenheit could trigger massive environmental changes, including melting of the Greenland ice sheet, the Himalayan-Tibetan glaciers and summer sea ice in the Arctic.
Corinne Le Quere, professor of environmental sciences at the University of East Anglia and the British Antarctic Survey, said the prediction that current emissions put the planet on track for a temperature rise of more than 11 degrees means the world could face a dangerous rise in sea level as well as other drastic changes.
Richard Moss, vice president and managing director for climate change at the World Wildlife Fund, said the new carbon figures and research showed that "we're already locked into more warming than we thought."
"We should be worried -- really worried," Moss told the Washington Post. "This is happening in the context of trying to reduce emissions."
The new data also shows that forests and oceans, which naturally take up much of the carbon dioxide humans emit, are having less impact. These "natural sinks" have absorbed 54% of carbon dioxide emissions released since 2000, a drop of 3 percentage points compared with the period between 1959 and 2000.
The pollution leader was China, followed by the United States, which past data show is the leader in emissions per person in carbon dioxide output. And although several developed countries slightly reduced output in 2007, the U.S. churned out more.
Still, it was large increases from China, India and other developing countries that spurred the growth of carbon dioxide pollution to a record high of 9.34 billion tons of carbon. Figures released by science agencies in the U.S., Great Britain and Australia show that China's added emissions accounted for more than half of the worldwide increase. China passed the U.S. as the No. 1 carbon dioxide polluter in 2006.
Emissions in the U.S. rose nearly 2% in 2007, after declining the previous year. The U.S. produced 1.75 billion tons of carbon.
"Things are happening very, very fast," Le Quere told the Associated Press. "It's scary."
Gregg Marland, a senior staff scientist at the U.S. Department of Energy's Oak Ridge National Laboratory in Tennessee, said he was surprised at the results because he thought world emissions would drop because of the economic downturn. That didn't happen.
"If we're going to do something [about reducing emissions], it's got to be different than what we're doing," he said.
The emissions are based on data from oil giant BP PLC, which show that China has become the major driver of world trends. China emitted 2 billion tons of carbon last year, up 7.5% from the previous year.
"We're shipping jobs offshore from the U.S., but we're also shipping carbon dioxide emissions with them," Marland said. "China is making fertilizer and cement and steel, and all of those are heavy energy-intensive industries."
Developing countries not asked to reduce greenhouse gases by the 1997 Kyoto treaty -- China and India are among them -- now account for 53% of carbon dioxide pollution. That group of nations surpassed industrialized ones in carbon dioxide emissions in 2005, an analysis of older figures shows.
India is in position to beat Russia for the No. 3 carbon dioxide polluter behind the U.S., Marland said. Indonesia's levels are increasing rapidly.
Denmark's emissions dropped 8%. The United Kingdom and Germany reduced carbon dioxide pollution by 3%, while France and Australia cut it by 2%.
But it remains unclear how much industrialized countries will be able to reduce their carbon output in the years to come, regardless of whether developing nations seek to restrain their greenhouse gas emissions. The federal government predicts U.S. fossil fuel consumption will increase. Japan, Canada and several other countries that committed to reducing their carbon emissions under the 1997 Kyoto Protocol have fallen far behind in meeting their targets.
Moreover, new scientific research suggests the globe is already destined for a greater worldwide temperature rise than predicted. Last month, two scientists from the Scripps Institution of Oceanography and UC San Diego published research showing that even if humans stopped generating greenhouse gases immediately, the world's average temperature would "most likely" increase by 4.3 degrees Fahrenheit by the end of this century.
Writing in the journal Proceedings of the National Academies of Science, they based their calculations on the fact that new air-quality measures worldwide are reducing the amount of fine particles, or aerosols, in the atmosphere and diminishing their cooling effect.
What is "kind of scary" is that the worldwide emissions growth is beyond the highest growth in fossil fuel predicted just two years ago by the Intergovernmental Panel on Climate Change, said Benjamin Santer, an atmospheric scientist at the Lawrence Livermore National Laboratory.
Under the panel's scenario then, temperatures would increase by somewhere between 4 and 11 degrees Fahrenheit by 2100.
If this trend continues for the century, we would be exceedingly lucky "for it just to be bad, as opposed to catastrophic," said Stanford University climate scientist Stephen H. Schneider.
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