When will the methane bomb go off?

In October, the participants of the international expedition on the research vessel “Akademik Mstislav Keldysh” recorded a record methane release in the East-Siberian Sea. Scientists note that this is not a single phenomenon, but a part of the large-scale process of degassing the bowels of the Arctic, associated with the thinning of the permafrost layer under conditions of warming. RIA Novosti together with experts understands the consequences for the planet of uncontrolled methane emissions and the risks they pose.
Why do we need permafrost

Up to 65 per cent of Russia’s territory is covered by permafrost, and more than 80 per cent of the world’s submerged permafrost is located on the Russian shelf. Its stability directly affects the prospects for economic activity in the Arctic. After all, on the permafrost, which has always been considered a reliable foundation, there are high-rise buildings in polar cities, offshore drilling platforms and port facilities, oil and gas pipelines, roads and railways. Melting of the permafrost will lead to the fact that all this infrastructure will be disturbed.

Average annual temperatures are rising in most regions of the planet, especially in the Arctic. If the temperature around the globe has increased by an average of 0.8 degrees Celsius over the past century and a half, then in the Arctic – by five degrees. The permafrost is melting rapidly and the upper limit of the permafrost is dropping ever lower. This is especially the case on the shelf, where the permafrost is in contact with warm water all year round, rather than with cold atmospheric air.

There is a layer of sediment underneath the permafrost. According to seismic studies conducted in the region by scientists from the Russian Academy of Sciences and subsoil users such as Rosneft and Gazprom, this layer is highly saturated with gases, primarily methane. On the weakened fault zones, gas penetrates the surface and comes out at the bottom of the sea in the form of sipes – gas fountains of various capacities.

Methane enters the gas-saturated sedimentary layer from gas hydrates or other even deeper sources. There is an opinion among scientists that giant deposits of gas hydrates are hidden under the Arctic shelf. As temperatures rise and pressures decrease, they decompose into gas and water. The release of gas is accompanied by a significant increase in pressure, which can lead not only to the extrusion of methane up the faults and cracks, but also to explosive events.

Under the sight of a climate gun

Methane is the strongest greenhouse gas, about 30 times more efficient than CO2. Today, the concentration of methane in the atmosphere is about two parts per million. At these values, the contribution of methane to the global greenhouse effect is estimated by the Intergovernmental Panel on Climate Change (IPCC) at the United Nations at 30 percent of the contribution of CO2.
If only two percent of the methane hidden in Arctic gas hydrates is released into the atmosphere, its concentration in the air will increase two to three times and its role in the greenhouse effect will be equal to that of carbon dioxide, which the entire global community is now calling for. In addition, methane emissions lead to a so-called positive feedback loop: as the planet heats up, more methane is released, which further increases global warming.

The main risk is that further warming up of the Arctic and liberation of the Arctic seas from surface ice may cause a sharp destruction of the permafrost layer and simultaneously release a huge mass of methane into the atmosphere, which will affect not only the climate of the Arctic region, but the planet as a whole. The scenario described in the scientific literature is called “methane hydrate shotgun” or “methane disaster”.

Too expensive gas

In 2013, economists from the UK and the Netherlands estimated the possible global damage from the “methane disaster” at $60 trillion, which is comparable to the size of world GDP for the year. These include drought-related agricultural losses and the consequences of storms, fires and sea-level rise. In the most extreme scenario, where five to ten percent of the methane from the gas hydrates under the Eastern Arctic seas will be released into the atmosphere within the next ten years, the planet’s temperature will increase by three degrees.

And this is a climatic disaster.

European economists based their calculations on the data on methane emissions on the shelf of the East Siberian seas, published in 2010 by Russian scientists headed by Corresponding Member of the Russian Academy of Sciences Igor Semiletov, head of the International Laboratory for Carbon Research of the Arctic Seas at Tomsk Polytechnic University.

Igor Semiletov has been leading an international scientific group on the Russian side to study the processes of permafrost degradation on the shelf of the Eastern Arctic seas for 15 years already. Scientists from Sweden, Italy, the USA, the Netherlands, Great Britain, and recently from China participate in the work of the group. With the support of the government and the Russian Science Foundation, the scientific project “Siberian Arctic Shelf as a source of greenhouse gases of planetary importance: quantitative assessment of flows and identification of possible environmental and climatic consequences” is currently being implemented on the basis of the Tomsk Polytechnic Institute.

Gas fountains

Over the past 15 years, 37 expeditions have been conducted, during which researchers have recorded and mapped thousands of methane fountains hitting the sea floor. And each time they visit the same places, they see that the volume of methane degassing is increasing. More and more mega-sipes are appearing, i.e. fountain zones with more than one kilometer in diameter. The first such area of massive bubble unloading was discovered by scientists in 2011. Now there are seven of them on the map, but the routes of the scientific vessel cover only a very small part of the shelf area, where similar processes take place. As for the first hundreds of meters of vines, they have already been identified about a thousand.

In October of this year in the East-Siberian Sea a record power surge was recorded. Scientists have observed how up to one thousand cubic meters of methane is released on the area of tens of square meters per day.
“During my 45 Arctic expeditions I have seen for the first time a sip of such power. Emissions were so strong that the water was literally boiling from methane bubbles. Even at a height of 20 meters above the water surface, the concentration of methane in the atmosphere was 16 parts per million. This is about ten times higher than the planetary average,” says Igor Semiletov to RIA Novosti.

Researchers have proven that the scale of methane emissions depends on the thickness of the submerged permafrost layer and the degree of its degradation. Data from comprehensive biochemical, geophysical and geological studies carried out between 2011 and 2016 have shown that in some areas of the East Siberian Arctic shelf, the permafrost roof has already reached depths of hydrate stability and that further destruction could cause massive gas emissions. In particular, during the re-drilling of four wells in 1982-1983, the authors found that the upper limit of the permafrost had fallen by more than five metres in the past 30 years.

The total amount of methane emissions on the shelf of the Russian Arctic seas is estimated by scientists at 20 million tons per year. According to IPCC reports, the entire world ocean allocates annually… About five million tons.
“It turns out that our shelf, which occupies less than one percent of the world’s oceans, emits four times more methane than the entire ocean. IPCC experts still write in their reports that by the end of this century, the level of underwater permafrost will drop by three meters, and in reality it has already dropped by 50-100 meters.

They base their conclusions on office calculations and models, and we really work in expeditions,” explains Igor Semiletov. – Back in 2010, we published an article summarizing the results of thousands of measurements, which showed that underwater permafrost is unstable. The waters of the East Siberian shelf are saturated with methane on one or two orders of magnitude relative to the concentrations that would have been if the permafrost had remained stable.

Airbag

According to academician Leopold Lobkovsky, one of the leading participants in research on the Arctic shelf, head of the geological direction of the Institute of Oceanology named after P.P. Shirshov of the Russian Academy of Sciences, no less dangerous than emissions is the gas-saturated layer of sedimentary rocks, regardless of whether it receives gas from gas hydrates or deep water sources.

“It already has gas, and this is the main danger. It is necessary to study the properties of the sedimentary layer in the construction and drilling zones,” says Academician Lobkovsky. – Methane emissions represent huge risks in drilling, exploration and production of hydrocarbons in the Arctic. As a rule, they are associated with active fault zones. Both drilling itself and the construction of platforms in such zones are very unsafe. There is always a risk of methane explosion. There are other risks as well. For example, areas of water density dilution form in mass methane emission zones. If a submarine gets into such an area, it can lose its buoyancy and fall to the bottom.

The scientist believes that methane emissions from the bottom of the Arctic seas are a longstanding process, unrelated to the increase in temperature observed in recent decades.

“In many areas of the Arctic shelf, the bottom is covered with mini-crater markers, which have formed at the site of methane emissions. This indicates that emissions have been occurring for at least several thousand years,” says Lobkovsky.

Bubbles and explosions

In contrast to the permafrost, which is permafrost-like and perforated in many places, through which methane “siphonite” is penetrating, the permafrost is still sufficiently strong and stable. But this does not mean that deep methane degassing in the Arctic terrestrial zone is not dangerous. Rather, on the contrary. Because here, this process is accompanied by explosions, where huge craters are formed.

Vasily Bogoyavlensky, a Corresponding Member of the Russian Academy of Sciences, Deputy Director for Science of the Institute of Oil and Gas Problems of the Russian Academy of Sciences, has been studying “Yamal craters” since their discovery in 2014. The formation of these structures, according to the scientist, is connected with volcanic processes like mud or cryovolcanic eruptions, when the gas bursting under pressure from the depths, carries to the surface all the material captured on the road.

“Abnormally high reservoir pressures occur in near-surface sediments, which are many times higher than not only hydrostatic but also lithostatic pressures. This results in powerful emissions – pneumatic emissions, often amplified by self-ignition and gas explosion. In these cases, giant craters over 50 meters deep are formed, and pieces of frozen rock and ice sheet thrown out by the explosion fly for many hundreds of meters. The size of some blocks is measured in tens of cubic meters,” explains the mechanism of the phenomenon.

Bogoyavlensky and his colleagues, who recently conducted a detailed analysis of the distribution of gas hydrates and hazardous gas-saturated objects in the waters of the Arctic, Atlantic and Pacific oceans, believe that cryovolcanic eruptions release into the atmosphere incomparably more methane than bubble emission on the shelf.
“In the Russian Arctic, we found more than ten such objects. In addition, more than seven thousand perennial bubbles, some of which pose a potential danger, and more than 400 lakes, the bottom of which is dotted with large craters of gas emissions, have been identified from space on Yamal,” says Bogoyavlensky.

Many of the objects that have been monitored by researchers for several years are characterized by episodic explosive events, which confirms the volcanic nature of the cratering process.
Reality of the threat

Scientists agree that the degradation of permafrost and methane emissions in the Arctic are objective processes whose consequences can be very serious. In order to really assess the scale of threats, it is necessary to continue research, identify new and monitor known objects. Especially those located near large oil and gas complexes, settlements, ports and infrastructure objects.

The topic of studying processes related to climate change in the Arctic goes far beyond the national interests of one country. This is a global problem that requires the combined efforts of the international community of scientists. And Russia has a great chance to lead this cooperation.