Researchers from Cambridge have introduced a new theory that aims to explain the origins of the craters first identified on the Yamal Peninsula in Siberia in 2014, commonly referred to as the “holes at the end of the world”.
According to a recent study published in Geophysical Research Letters, these enigmatic cylindrical holes in the permafrost, which is consistently frozen ground, resulted from pressure fluctuations driven by climate change that explosively released subsurface frozen methane.
The unique geology of the region, combined with climate warming, initiated a process that facilitated the release of methane gas from methane hydrates found in permafrost.
“There are very, very specific conditions that permit this phenomenon to take place,” remarked Ana Morgado, a chemical engineer at the University of Cambridge and a co-author of the study.
The “holes at the end of the world”
The Yamal Peninsula is a low-lying landmass extending into the Kara Sea from the northern central part of Russia. In 2014, a crater approximately 70 meters in diameter at its widest point was reported to have appeared suddenly in the permafrost. Over the subsequent decade, additional craters have been discovered on both the Yamal Peninsula and the adjacent Gydan Peninsula.
Numerous theories regarding the craters have emerged over the past decade, attributing the blasts to an accumulation of methane gas underground due to melting permafrost or the craters’ proximity to natural gas reserves.
However, the authors concluded that warming permafrost alone would not suffice to trigger an explosion. The new explanation posits that surface heating results in a rapid pressure change deep underground, which causes the release of explosive methane gas.
“We knew something was prompting the methane hydrate layer to disintegrate,” Morgado stated. “It’s akin to detective work.”
The researchers approached the puzzle from the ground up, first addressing a fundamental question: Were the explosions initiated by physical or chemical processes?
Physics or chemistry?
“There are only two methods by which an explosion can occur,” explains Julyan Cartwright, a geophysicist with Spain’s Higher Council for Scientific Research and another author of the study. “Either a chemical reaction takes place and results in an explosion, like dynamite, or a bicycle tire is inflated until it bursts; that’s physics.”
In this instance, he notes that there was no evidence to suggest the explosions resulted from chemical reactions, indicating they must have had a physical origin. “Then you have to consider, what is the mechanism that inflates the bicycle tire?” he adds.
The authors assert that the mechanism was osmosis, which is the process by which a fluid moves to equalize the concentration of solutes. Salt water serves as a classic illustration. If a barrier exists that permits water to flow through but blocks salt, pressure can accumulate on the salty side as water makes its way toward it.
The Yamal Peninsula’s dense, clay-rich permafrost functions as an osmotic barrier, which is undergoing changes due to warming. This layer, ranging from 180 to 300 meters thick, remains perpetually frozen year-round. An “active layer” of topsoil above it thaws and refreezes seasonally.
Embedded within the tundra and contained in the permafrost are peculiar meter-thick layers of unfrozen, high-salinity water known as cryopegs, which remain liquid due to a combination of pressure and salinity. Beneath the cryopegs lies a layer of crystallized methane and water solids, referred to as methane hydrates, which remain stable due to high pressure and low temperatures.
However, increasing temperatures are destabilizing these layers. Climate change has caused the active layer to melt and extend downward until it encounters the cryopeg, releasing water that moves toward the cryopeg through osmotic pressure, according to the researchers.
Geophysical Research Letters
However, there isn’t sufficient space in the cryopeg to accommodate the additional meltwater propelled by osmosis, resulting in increased pressure. This rising pressure creates fissures in the ground that extend upward from the cryopeg toward the surface. Consequently, the pressure gradient reverses: the fractured soil induces a sudden drop in pressure at depth. This change in pressure compromises the methane hydrates beneath the cryopeg, triggering a release of methane gas and a physical explosion.
The study indicated that the lead-up to the explosion can span decades. This timeline aligns with the onset of increasing climate warming beginning in the 1980s.
The new explanation hinges on the interaction between climate warming and the region’s geology to generate the explosions unique to the Yamal Peninsula.
“This could be a phenomenon that occurs very infrequently,” Morgado noted. “However, the volume of methane being released could significantly influence global warming.”
Cambridge scientists propose a new theory that explains how the craters first seen on the Yamal Peninsula in Siberia in 2014, known as the “holes at the end of the world”.
These mysterious cylindrical holes in the permafrost, the always frozen ground, were caused by pressure changes driven by climate change that explosively released frozen methane underground according to the new study published in
Geophysical Research Letters.
The region’s unusual geology, along with climate warming, began a process that led to the release of methane gas from methane hydrates in permafrost.
The “holes at the end of the world”
The Yamal Peninsula is a low-lying landmass jutting into the Kara Sea from north-central Russia. In 2014, a crater approximately 70 meters in diameter at its widest point was reported to suddenly appear in the permafrost. Over the following decade, other craters have been found on both the Yamal Peninsula and the nearby Gydan Peninsula.
Many explanations for the craters have emerged over the past 10 years, attributing the explosions to a buildup of methane gas underground due to melting permafrost, or to the craters’ proximity to natural gas reserves.
But the authors discovered that warming permafrost alone would not be enough to cause an explosion. The new explanation states that surface heating leads to a rapid change in pressure deep underground, causing the release of explosive methane gas.
“We knew something was causing the methane hydrate layer to break down,” Morgado said. “It’s a bit like detective work.”
Physics or Chemistry?
“There are only two ways for an explosion to occur,” says Julyan Cartwright, a geophysicist at Spain’s Higher Council for Scientific Research and one of the authors of the study. “Or a chemical reaction occurs and an explosion occurs, like dynamite, or the bicycle tire is inflated until it explodes; that’s physics.”
In this case, he says, there was no evidence that the explosions were caused by chemical reactions, so they must have had a physical source. “And then you have to think, what is the pump that inflates the bicycle tire?” he says.
The authors state that The pump was osmosis, which is the way a fluid moves to equalize the concentration of substances dissolved in it. Salt water is a classic example. If a barrier exists that allows water to pass through, but not salt, pressure can build up on the salty side as water flows toward it.
Understanding Osmosis in Context
The Yamal Peninsula’s thick, clayey permafrost acts as an osmotic barrier, and warming temperatures are changing it. This layer, between 180 and 300 meters thick, remains permanently frozen throughout the year. An “active layer” of topsoil above it thaws and refreezes seasonally.
Scattered throughout the tundra and encased within the permafrost are unusual meter-thick layers of unfrozen, high-salinity water called cryopegs, which are kept liquid by a combination of pressure and salinity. Beneath the cryopegs is a layer of crystallized methane and water solids, called methane hydrates, which are kept stable by high pressure and low temperature.
Impact of Climate Change
But warmer temperatures are destabilizing these layers. Climate change has caused the active layer to melt and expand downward until it reaches cryopeg, releasing water that travels through osmotic pressure toward the cryopeg, the researchers discovered.
But there is not enough room in the cryopeg to contain the additional meltwater forced by osmosis, so the pressure increases. The increasing pressure creates cracks in the ground that move upward from the cryopeg toward the surface. Then the pressure gradient reverses: the cracked soil causes a sudden drop in pressure at depth. That pressure change damages the methane hydrates beneath the cryopeg, causing a release of methane gas and a physical explosion.
Timeline and Future Implications
The study found that the period leading up to the explosion can last decades. That timeline aligns with increasing climate warming starting in the 1980s.
The new explanation depends on how climate warming and the region’s geology interact to create the explosions, which are unique to the Yamal Peninsula.
The Potential Impact of Methane Release
“This could be a phenomenon that occurs very infrequently,” Morgado said. “But the amount of methane that is being released could have a pretty big impact on global warming.”
Table: Comparison of Explosive Mechanisms
| Mechanism | Process Type | Cause of Explosion |
|---|---|---|
| Chemical Reaction | Chemistry | Dynamite or other explosive substances |
| Osmosis Pressure | Physics | Increase in trapped water pressure leading to methane release |
Case Studies and Observations
Scientists continue to investigate the impact of these methane releases on climate change. Observations from the Yamal Peninsula reveal how interconnected geological, chemical, and physical processes are influenced by climate change. Continued monitoring is essential in understanding the full implications of these eruptions on global warming.
Practical Tips for Awareness
- Stay Informed: Keep up with ongoing research and findings regarding climate change and methane release.
- Support Climate Initiatives: Get involved in local and global initiatives promoting climate action.
- Share Knowledge: Educate others about the roles of permafrost and methane in our climate systems.
First-hand Experiences
Researchers and locals have begun documenting their experiences around these explosions. Eyewitness accounts help paint a vivid picture of the changes occurring in this Siberian landscape.
