Arctic methane

 

Methane and halogenated compounds

One of the reasons lies in halogenated compounds such as chlorofluorocarbons (CFC) and hydrofluorocarbons (HFC), which were already responsible for the hole in the ozone layer above the Antarctic in the 1980s. These gases, according to the researchers of the Columbia University (United States), were responsible for a third of climate warming between 1955 and 2005, and half the warming of the Arctic and the ice melt observed during this period! These halogenated compounds were invented in the 1920s – 1930s to be used as coolants, solvents and propellants. In 1987, 197 countries accepted to progressively stop consuming these  substances that deplete the ozone layer, by ratifying the Montreal protocol. The success of this historic international agreement led to the reduction of CFC emissions to nearly zero level. Nonetheless, the recovery of the ozone layer is a slow process, since CFCs remain in the atmosphere for decades.

However, there is another even more worrying piece of news: the progressive release of methane naturally sequestered on the ocean seabed. This gas has 23 times the heating power of CO₂, and the quantity stored in the ice and on the ocean seabed represents twice the quantity of coal and oil that human beings have already consumed. It is starting to become gaseous and enter into the atmosphere in quite substantial quantities under the effect of climate change. Large plumes of methane have been observed in the Arctic Ocean, rising from the seabed to the surface of the water. Permafrost thawing is another natural and potentially catastrophic source. 1,600 billion tonnes of carbon are stored in these frozen soils, twice as much as in the atmosphere. With increased heating in the Arctic, this carbon could enter the atmosphere as carbon dioxide (CO₂) for the most part, but also as methane (CH₄).

No decrease in anthropic emissions

Although no significant increase in methane emissions resulting from permafrost thawing has been detected as yet, emissions resulting from the extraction of fossil fuels are increasing. They are, after the many expanses of peatland present in these regions which discharge methane naturally, the second major source of methane in the Arctic.

The region represents a quarter of the world’s methane emissions linked to the exploitation of oil and gas. However, the Arctic has large deposits whose exploitation, despite the high cost of the logistics involved in these extreme environments, is supported by global demand. The region contains between 14 and 25% of the world’s non-discovered oil resources.

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