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METHANE... AND HOTHOUSE EFFECT

Дата публикации: 08 сентября 2018
Автор: Georgi GOLITSYN
Публикатор: Шамолдин Алексей Аркадьевич
Рубрика: ЭКОЛОГИЯ
Номер публикации: №1536413177 / Жалобы? Ошибка? Выделите проблемный текст и нажмите CTRL+ENTER!


Georgi GOLITSYN, (c)

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By Academician Georgi GOLITSYN, director of the A.M. Obukhov Institute of Physics of the Atmosphere, Russian Academy of Sciences

The problem of global warming is much in the public mind now, and there are facts to justify this concern. But it is not clear yet whether natural causes or human activities are to blame. Be that as it may, the Kyoto Protocol of 1997 sets carbon dioxide (CO 2 ) discharge standards for each and every country. For all the importance of combating excessive concentrations of CO 2 , this gas poses no hazard per se. Its enhanced concentration, however, can catalyze the release of a harmful hothouse gas, methane (CH 4 ). As shown by preliminary studies, CH 4 accumulation can activate the overall hothouse effect and even set off a mechanism of its vigorous self- enhancement.

And that would mean a global disaster.

Methane (CH 4 ) is the essential component of natural gases (77 to 99 percent). It is present in associated (31 to 90 percent), mine and marsh (methane) gases. Although CH 4 is always found in the atmosphere, its concentration depends on many factors. For one, on the ocean temperature, since cold water readily absorbs all the various gases, methane too.

As a matter of fact, the concentration of CO 2 , CH 4 and other hothouse gases* goes up during warming spells. This has been proved by an international team of experts involved with the composition of our planet's atmosphere in the dim and distant past. Studying the chemical composition of air vesicles in arctic ice core samples, they have traced the record of the earth's atmosphere over the past five hundred thousand years. Russian scientists (Academician Vladimir Kotlyakov and others) made a crucial contribution: it was at the Russian Antarctic station VOSTOK that ice samples were extracted as deep as 3,623 m in the 1960s, 1970s and 1980s*.

Among other things, we now have data on the presence of methane in the atmosphere in different periods. Its concentration started increasing about 400 years ago, and today it is three times as high as it was in the beginning of the 17th century. Scientists attribute this dramatic increase to human activities: expanding rice paddies, cattle herds and industries, mining industries in particular (extraction of coal, oil, natural gas and minerals).

Methane is a strong hothouse gas indeed, 21 times more potent than carbon dioxide in its heat-absorbing characteristics. It is more effective in screening the atmosphere and in keeping CO 2 in. Thus heated, the upper layers of the atmosphere stimulate CH 4 release, which means that more of the heat radiation will remain in the air. This triggers a self-enhancement mechanism of the hothouse effect that would not be so easy to arrest.

Now, how does methane get into the atmosphere? Where from? Apart from man's activities (industry, farming), CH 4 escapes from the earth's interior which has a vast pool of natural gases, CH 4 for the most part, at a significant depth, several kilometers under.

Geologists have discovered large deposits of methane in the Atlantic


* Carbon dioxide, methane and other gases absorb the heat rising from the planet's surface and thus increase air temperature.- Ed.

* See: V. Kotlyakov, "Environment, its Past and Future: Glaciology Bears Witness", Science in Russia, No. 1, 2001.- Ed.

Articles in this rubric reflect the opinion of the author.- Ed.

Pages. 41


near Iceland at a depth of only 200 - 300 m beneath the ocean floor*. It can escape from this pool too, say, through the guilt of gas miners, in consequence of a technogenic disaster in drilling rigs and units, or just because of a rise in ocean water temperature. This may boost-manifold!-the CH 4 concentration in the atmosphere and upset the radiation balance on the terrestrial surface; the hothouse effect will thus increase greatly.

The world ocean is a potential producer of hothouse gases. A global warming (which is most unlikely to occur in the next few centuries) may cause the excess of CO 2 , CH 4 and other gases dissolved in ocean water to escape. To estimate the amount of methane or some other gas to be released this way, we should develop models for atmosphere ocean interaction and carry out corresponding model computations.

Permafrost-bound boglands are yet another CH 4 source. Should their areas contract in a probable global warming, significant amounts of methane will escape. But how much? We cannot tell yet without appropriate research.

Permafrost poses no threat so far. Together with the RAS Institute of Geography we have completed studies to find out how "intact" permafrost is (rather, its surface layer)*. What with 60 percent of Russia's territory being in the permafrost zone, this is an all-important problem. We intend to keep up our studies in this area. We have planned thrilling experiments jointly with the Institute of Computing Mathematics in trying to forecast what will happen to permafrost during this century. Our tentative estimates show: every degree


* See: Yu. Genschaft, "Iceland: Geodynamic Phenomenon", Science in Russia, No. 5, 2000. -Ed.

* See: A. Velichko, "Climatic Warming: Glimpse into the Future", Science in Russia, No. 3, 2002. -Ed.

Pages. 42


(on the centigrade scale) of global temperature rise is tantamount to a loss of up to 30 percent of the planet's permafrost.

In order to prognosticate global climatic changes we should design models making it possible to assess-in real time naturally- how much of CO 2 , CH 4 and other hothouse gases could be released into the atmosphere, and how much would be absorbed by wetlands, oceans and other bodies of water. This will enable humankind to get ready for various global scenarios, untoward ones including.

Our Institute has long been involved with this work. Our model experiments on the atmosphere/ocean circulation allow for possible changes in the concentration of hothouse gases, CH 4 too, in the earth's air envelope: during this century the mean temperature on Russian territory may be up 1 to 2 o C. Overall, this may have a favorable effect on farming. However, our models predict an increase in the total amount of precipitation because of the change in the pathways of cyclones. This prognosis agrees with the observation data: the last harsh drought hit this country way back in 1975.

But even though the total amount of precipitation may increase, it will be concentrated within particular seasons. That is the number of torrential rain days could go up. And this is fraught with natural calamities. One such disaster occurred in the Stavropol and Krasnodar Territories (Russia's south) in July 2002: violent floods killed more than a hundred and inflicted great damage on the national economy.

Опубликовано 08 сентября 2018 года




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