Global warming: ‘The methane threat’…

TICKING TIME BOMB

SCIENTISTS are uncovering a new global warming threat as melting permafrost releases millions of tons of methane gas, calculated to be 20-times more damaging than carbon dioxide.

Early findings suggest that huge deposits of subsea methane are bubbling to the surface due to the Arctic region having become warmer and its ice retreating through the effects of global warming.

Underground storage of methane is important because any sudden release of the gas in the past has largely been responsible for rapid and exponential increases in global atmospheric temperatures, has altered climatic patterns quite dramatically and has even been responsible for the mass extinction of species. Scientific researches undertaking studies have sailed the entire length of Russia’s northern coast and have discovered intense concentrations of methane that extend over several areas covering thousands of square miles of the Siberian continental shelf.

Just in the last few days, researchers have observed and recorded areas of sea foaming with gas bubbling up through methane chimneys rising from the sea bed. It is now reckoned that the sub-sea layer of permafrost, which has acted almost like a lid in preventing the methane from escaping, has melted away to allow the gas to rise from underground deposits formed before the last ice age. Essentially, if atmospheric temperatures have increased then, by definition, this must increase the temperature of water, with the resulting melting of ice that is now being observed. When water is warmed it expands, too. Hence, the rising sea levels.

Photo Credit: Getty Images -- Researchers believe the Arctic Ocean seabed is thawing in patches and releasing greenhouse gases

With methane being around 20-times more powerful than carbon dioxide as a greenhouse gas, scientists fear that its release from containment (ice) could accelerate global warming through positive feedback mechanisms that could produce a domino-style effect: atmospheric methane causes higher temperatures, leading to further melting permafrost with the release of yet more methane, and so on.

The volume of methane stored beneath the Arctic is calculated to be greater than the total amount of carbon locked-up in global coal reserves. With the Arctic region warming at a faster rate than any other place on earth, expect intense interest in the stability of these deposits in the coming weeks and months.

 

E-MAIL

Dr. 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:

… An extensive area of intense methane release was found. At earlier sites we had found elevated levels of dissolved methane. Yesterday (Tuesday, 23 September 2008) 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 various locations during the research, some concentrations of methane were known to have reached at least 100 times background levels. Specifically, such wide variations were observed and recorded within the East Siberian Sea and the Laptev Sea, covering tens of thousands of square kilometers, but amounting to millions of tons of methane.

Dr. Gutafsson suggests that the scale of things being reported is probably of the same magnitude previously estimated from the global ocean. What is difficult to determine, though, is how many more such areas exist on the extensive East 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 findings, so far, of the International Siberian Shelf Study (2008), are currently being collated and prepared for publication by the American Geophysical Union. This work is being overseen by Igor Semiletov on behalf of the Russian Academy of Sciences. Since 1994, Mr. Semiletov has led some 10 expeditions in the Laptev Sea. During the 90s, though, tests undertaken didn’t detect any elevated levels of methane. However, since 2003, the Russian scientist has reported a rising number of methane hotspots, which have been confirmed using more sensitive instruments on board the Jacob Smirnitskyi.

Dr Semiletov has put forward several possible reasons why methane is now being released from the Arctic region, including the rising volume of relatively warmer water being discharged from Siberia’s rivers due to the melting of the permafrost on the land.

Over recent decades, the Arctic region as a whole has experienced a 4°C rise in average temperatures, as well as suffering dramatic declines in summer ice covering the Arctic Ocean. Many scientists and environmentalists fear that the loss of sea ice could accelerate the warming trend because open sea soaks up more heat from the sun than the reflective surface of an ice-covered sea (see albedo effect).

 

© Mark Dowe 2008: all rights protected

The writer campaigns on behalf of WWF (Scotland) and is a holder of an M.Sc in Geography

- Copyright is the currency by which information may be exchanged in certain instances. If you are unsure of your rights relating to digital communications in partial or complete form you should seek independent legal advice.

mark.dowe@googlemail.com

 

EMPIRICAL STUDY

AS THE CHINESE ECONOMY has exponentially grown in the last decade it has been linked with a rise in emissions of man-made methane.

Methane has, largely, been regarded as the second most important greenhouse gas and, per ratio of molecule, is around 20-times as potent as carbon dioxide in its ability to exasperate the effects of global warming and climate change.

Levels of methane in the atmosphere have risen since the Industrial Revolution but, in years running up to 2006, the gas appeared to have stabilised. Many scientists believed that because of such trends the gas may not have been so critical in terms of global warming. However, research data released by the scientists in the above article suggests that methane may be the greatest threat to the survival of the earth. However, methane level decline in the 1990s is attributed to the drying out of wetland areas due to climate change, which actually suppressed a major natural source of gas.

Scientists concluded with a reasonable degree of certainty that this masked a significant increase in man-made sources of methane from booming Asian economies, particularly China, whose economy now has more than doubled since the late 1990s.

The slowdown in recent decades of global methane emissions has proved now to have been only temporary. It looks as if previous reports claiming that emissions were under control were greatly exaggerated. What is certain, though, is that had this reduction in methane emissions from wetlands not occurred, atmospheric levels of methane gas would most likely have continued rising. Moreover, what this suggests is that if the drying trend is reversed and emissions from wetlands and bog marshes return to normal, then the likelihood is that atmospheric methane will rise again, worsening the problem of climate change.

Presently, around two-thirds of global methane comes from man-made sources, such as the burning of fossil fuels, accidental release during drilling for natural gas or from cattle ranching. Levels recorded globally can be affected by natural phenomena such as the El Niño ocean current and volcanic eruptions. These may vary enormously from year to year, and from hemisphere to hemisphere.

The largest natural source of methane comes from bacterial decomposition of organic matter in wetlands. Once released to the atmosphere, however, the gas can be quickly broken down.

Scientific investigation includes teasing apart the sources of methane using computerised simulations that attempts to explain how the gas has been transported through the atmosphere over the past 20 years. They use a method of tracing based on the concentration levels of a carbon isotope – methane emissions from wetlands, for example, are significantly depleted in this isotope.

Indicatively, studies have also shown that the rapid growth of Asian economies, including the rapid use of fossil fuels, has led to an upturn in man-made emissions of methane since the late 1990s.

Conclusively, what this demonstrates is that there have been two opposing processes at work that together have resulted in stable methane emissions with little or no increase in atmospheric concentration over the past 10 years or so. On the one hand, wetlands have been drying up and thus emitting less methane whilst on the other economic growth in the northern hemisphere, especially in China, has generated increasing amounts of methane from the mining and the use of fossil fuels.

Though it is difficult to predict with certainty what will happen to wetlands in the future, it is likely that aggregate methane levels in the atmosphere will increase in the future, due to the increasing demand for energy.

Whilst scientists and environmentalists agree that methane is an important greenhouse gas, further studies and research will become important in understanding why methane emissions are changing. However, the inexorable and unremitting increases in carbon dioxide emissions from fossil fuels will continue to be the most important driver of global warming.