Sinkholes as big as a skyscraper and as wide as a city street open up in the Arctic seafloor

Scientists have discovered that one of the giantsinkholes that could devour an entire city block is appearing along theArctic seafloor.

Even though climate change is increasing the average temperatures, the thawing of the permafrost that is creating these sinkholes seems to have a different cause.

Since the end of the last ice age, when glaciers blanketed the region, the bottom of the Canadian Beaufort Sea has been submerged. Scientists had been looking at the frozen seafloor. Climate change has caused the sea ice to retreat in the remote part of the Arctic, making it accessible to researchers on ships.

Mapping the seafloor

With access to the area, the study researchers relied on both ship-based and an AUV to complete high-resolution bathymetric surveys.

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We know that big changes are happening across theArctic landscape, but this is the first time we have been able to deploy technology to see that changes are happening offshore as well.

The Last Ice Area may not survive climate change.

The researchers focused on the shelf edge and slope in the Canadian Beaufort Sea when they first started doing seafloor surveys. A band of rough terrain was spotted about 120 miles from the shore. During the last ice age, that stretch of seafloor marked the edge of the permafrost. The team wondered what was making the ocean bottom rugged.

The team conducted three more surveys using AUVs in the past two years to understand how this roughness evolved over time. The emergence of steep-sided and irregularly shaped depressions were shown in the snapshots. The largest crater is 738 feet long, 263 feet wide and 92 feet deep.

Collapsing floor

The researchers propose that the circular holes are forming because the area used to be filled with a solid. The surface material collapses into that liquid-filled void over time, the researchers said.

Why do ice ages happen?

In areas where the discharge of this warm groundwater is more limited, the water on the floor stays cold enough to cause the ground to refreeze. The ice expands and forms little conical mounds called pingos. The mounds interrupted by the sinkholes are responsible for the unusual roughness that the researchers first spotted.

The researchers wrote in their research article that the continued enlargement of some depressions observed over multiple surveys indicates that the development of these depressions is part of on-going processes.

Slow changes in climate related to the end of the last ice age are likely to be the cause of the cycle. Once the submerged permafrost begins to melt, the heated water from that melted permafrost inches upward along the bottom of the still-frozen permafrost, leading to more thaw of those sediments above. The process continues in this way to give birth.

It was originally published on Live Science.