MOSCOW. (Dmitry Zamolodchikov for RIA Novosti) - The emerging permafrost thaw is causing panic.
This is understandable in Russia since a large portion of its land is covered in permafrost.
Journalists and scientists are coming up with many hair-raising forecasts of an environmental disaster where millions of cubic meters of marsh gas, or methane, are released into the atmosphere. But is the atmosphere in real danger?
Field studies prove that the tundra and Arctic lakes do emit more marsh gas than usual because of the warming climate. The crucial question, however, remains unanswered-is the increase sufficient to notably change the global concentration of marsh gas in the air?
Methane is one of the gases involved in the greenhouse effect, with a potential exceeding that of notorious carbon dioxide by 25 times. Its atmospheric concentration, however, is 210 times less, so its contribution to the greenhouse effect is a mere 12% of carbon dioxide's.
The concentration of marsh gas in the air was 50% greater in the 20th century than during the preindustrial era before 1750. Its rapid increase made scientists suspect global warming as the catalyst. If this is so, the world is caught in a vicious cycle: the warmer the climate the more methane and the more methane the warmer the climate.
Modern science assumes that this occurs on the Arctic dry land and sea shelf as the permafrost thaws. That is why many regard the Russian permafrost belt as a climatic booby trap ready to go off at any instant and suffocate the world.
There are two widespread hypotheses on methane emission increase in the Arctic. The first concerns methane-emitting bacteria in continental ecosystems. The thawing permafrost activates certain amounts of hitherto passive organic substance, which interferes in the local biological and geological cycles. The humid tundra, marshland and Arctic lakes become a paradise for such bacteria feeding on those organic substances.
The other Arctic methane emission factor has been attributed to the sea shelf and clusters of gas hydrates that are chemical compounds in which methane molecules are blanketed in water crystals. They resemble ice or slush in their appearance and physical properties. The crystals melt releasing methane into the atmosphere and contributing to the greenhouse effect.
The Pacific Institute of Ocean Studies, based in Vladivostok, recently registered high levels of methane concentration in the Laptev Sea. Experts blame decomposing gas hydrates.
Model studies at the Moscow State University Geology Department show something quite to the contrary: methane hydrates respond to climate changes 20,000 to 40,000 years after the fact. Besides, not only temperatures but pressure also determines gas hydrate stability. Stability is maintained at a depth of 5 kilometers, with 500 atmospheres of pressure, even at 5 degrees Celsius. This is why gas hydrates are found not only in the Arctic, but all over the world on the sea shelf and underwater slopes. The depth makes the only difference: starting at 200 meters in the Arctic and 500-700 meters in warmer waters. The rising sea level increases pressure at certain depths, which expands the area of methane hydrate stability.
Other factors also make us doubt that methane threatens to flood into the air as its hydrates decompose. In particular, many bottom hydrate clusters have a watertight crust. Also reassuring is the slow pace of methane progress upward since a large portion of the gas oxidizes on the way.
Detailed studies at the State Hydrology Institute in St. Petersburg allow one to assume that biogenic methane emission in the Russian permafrost zone cannot increase by more than 20%, or at the most 30%, compared to the current level, which would cause global warming by 0.01 degrees Celsius by 2050. This is negligible when compared to industrial warming.
There is another major reason for optimism. The mighty global increase of methane concentration in the air that haunted humanity in the 20th century has been reduced to almost nothing since 2000. Peak warm spells that occurred in the 20th century caused the Arctic Ocean ice shield to shrink drastically and permafrost to thaw in the tundra to an unprecedented depth. All this allows us hope that the permafrost belt is not the methane booby trap it is painted to be.
Dmitry Zamolodchikov is professor of Moscow State University.
The opinions expressed in this article are the author's and do not necessarily represent those of RIA Novosti.
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