Ive here. As if you didn’t worry enough about climate change, there’s now flooded permafrost to add to the list.

By Matt Simon, science reporter for Wired.Originally Posted by wired and from dark as part of climate desk cooperate

A sort ofAbout 20,000 years ago, The world is so cold that giant glaciers have absorbed enough water to lower sea levels by 400 feet. As the sea receded, newly exposed land froze to form permafrost, a mix of mud and ice that is now widespread in the far north. But as the world warms to the climate we enjoy today (for the time being), sea levels rose again, flooding coastal edges of permafrost that remained frozen underwater.

It’s a huge, hidden climate variable that scientists are racing to understand. They know very well, terrestrialPermafrost is an important source of carbon entering the atmosphere. As it melts, microbes chew on the organic matter it contains, releasing carbon dioxide (if the material is fairly dry) and methane (if the melted ice forms a pond).This can create a feedback loop in which more permafrost thaws produces more emissions that heat the planet to thaw Even Permafrost.This is a particularly big problem because the North Pole is warming now four times faster Just like everyone else on earth.

However, seafloor permafrost is largely unstudied due to its inaccessibility – time to rent a research vessel is not cheap anywhere, let alone in the Arctic, and drilling samples are harder to find.Now, in a shocking Paper An international team of scientists published last week in the Proceedings of the National Academy of Sciences gave us a rare glimpse into what’s going on there. The team used marine robots that looked like torpedoes off Canada’s northern coast and used sonar to map the ocean floor. The scientists repeated it several times over a nine-year period to understand how the topology of the ocean floor might be changing, and found that it was undergoing dramatic upheavals.

The result is the worrisome image shown below – a massive sinkhole indicating that the permafrost on the seafloor has thawed and collapsed. The sinkhole is one gigantic among dozens of pits that researchers have found on the ocean floor. Scientists have documented this violence, thermokarst, landing. Because permafrost is made up of soil suspended in a matrix of frozen water, when it thaws, the land shrinks, digging huge holes in the Arctic landscape. It’s also happening underwater, as these seafloor images show.

Repeated mapping using autonomous underwater vehicles has revealed a massive sinkhole on the bottom of the Arctic. Melting permafrost ice has left voids where the seafloor has collapsed. Visual: Eve Lundsten/MBARI

“I think it’s absolutely remarkable that some parts of the ocean floor are changing at this rate and on this scale,” said Charlie Paul, a marine geologist at the Monterey Bay Aquarium Research Institute and co-author of the paper. The survey covered an area half the size of Manhattan, with a total of 40 holes. (You can see part of the area in the image below.) The gigantic “equivalent to an entire New York City block made up of six-story apartment buildings,” he said.

Why is this happening? On land, permafrost is melting due to rising temperatures. But, Paul said, there’s no evidence the seafloor has warmed enough to start thawing.So thawing is most likely not from above, but from the following. The permafrost on the seafloor formed a thick wedge that could be several hundred meters, Paul said. Relatively warm groundwater flows underground, which can degrade permafrost. “If it’s pure permafrost ice, it creates voids that then collapse,” he said. “We therefore infer that the voids we see in this environment are the result of long-term warming of the seafloor in the region.”

That long Bits are important. Unlike rapid melting on land, this degradation of the seafloor may have unfolded over longer timescales — a lingering effect of how much the world has warmed since the last ice age. “I think the biggest lesson of this paper is a reminder of how long these systems take to respond,” said Ben Abbott, who studies permafrost at Brigham Young University but was not involved in the study. “You might misinterpret it as, ‘Oh, nothing to worry about.’ I actually came to the exact opposite conclusion. Once the system is up and running, we have very little ability to change its direction. This is not a car with a steering wheel— – It’s more like a boulder you push off the top of a mountain.”

Unusually rough seafloor topography created by thawing seafloor permafrost at the edge of Canada’s Arctic continental shelf. The entire survey covers an area half the size of Manhattan, with a total of 40 holes. Visual: Eve Lundsten/MBARI

While this seafloor melting may be driven by long-term processes, scientists fear it could be accelerating because the Arctic is warming so rapidly now. Ocean circulation patterns may also change, bringing in more warm water. “So long-term changes of the kind we observe now may soon be accelerated by human interference with the climate,” Abbott said.

The two big unknowns are how much seafloor permafrost exists and how much greenhouse gas it holds. Scientists can’t sample every square foot of the Arctic seabed, so they look back and compare the area of ??land exposed during the last glacial maximum thousands of years ago with the area of ??land exposed today. This gave them an idea of ??how much permafrost may have formed and then submerged when glaciers melted and sea levels rose to where they are now.Estimates vary, but there may be 775,000 square miles Seafloor permafrost, which stores tens of billions of tons of organic carbon and billions of tons of methane.

Methane is a serious climate threatbecause it is 80 times stronger A greenhouse gas as carbon dioxide (though it disappears from the atmosphere much faster). In terrestrial permafrost, it’s produced when microbes have moist organic material to chew on — apparently the seafloor is pretty wet. But seafloor methane also comes from underlying natural gas deposits that leak upward and become trapped in lattices of frozen water, a solid known as methane hydrate. (basically gaseous ice; it will even ignite.) These molecules “just sit there waiting for the temperature threshold to be crossed, and then they can be released very dramatically,” Abbott said.

When methane is released from seafloor permafrost, microbes in the sediment and water column process it into carbon dioxide. “This has been described as a ‘microbial cap’ that protects us from methane release, as it converts the very potent greenhouse gas methane into the less potent gas carbon dioxide,” Abbott said. “However, if we had a massive subsea permafrost collapse – like the one described in this paper – we might release more methane in the bubbles, which is questionable. This bubbling would make the methane more Microbial oxidation short-circuits and releases it directly into the atmosphere.”

It’s hard to say exactly how the thawing would work, because permafrost on the seafloor is a time capsule and can’t be directly compared to permafrost on land. “It’s this ancient legacy environment that’s basically cut off by the expansion of these ocean waters,” said Merritt Turecki, an ecologist at the University of Colorado Boulder who studies permafrost but was not involved in the new paper. But when you combine potential seafloor emissions with the amount of gas known to be emitted from land — which Turetsky says is “like adding another industrialized country to the world” — the climate impact can be huge.

“We like to say that what happens in the Arctic doesn’t stay in the Arctic,” she said. Think of this region as the Earth’s freezer, which has locked up carbon for thousands of years. “We’re going to unplug the refrigerator from the wall now,” Turetsky said. “We’ve got this warming hotspot —cool down Hero for thousands of years, but now it is possible to release all stored carbon back into the atmosphere. “