Underwater ice structures recently discovered on the Arctic seafloor are leaving scientists baffled
In one expedition In the Beaufort Sea in the Canadian Arctic, researchers have made a surprising discovery: vast underwater ice formations in a previously unexplored region.
Using advanced technology from Monterey Bay Aquarium Research Institute (MBARI), the team found these formations while investigating the impact of melting permafrost underwater, a phenomenon resulting from climatic processes and ancient geological.
This discovery attracted attention because it revealed an unknown process of ice formation on the seabed, caused by the migration and refreezing of waters brackish underground.
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These waters are generated by the melting of ancient submerged permafrost, which, when rising to the surface, freezes upon coming into contact with the cold waters at the bottom of the ocean.
The origin of modern ice waders submarine in the Arctic Sea
The ice sheets observed are not the same as those formed during the last ice age, but are of more recent origin.
They result from the thawing of deeper layers of underwater permafrost, which releases brackish water. This water, when rising to colder layers near the surface of the seabed, refreezes.
The average temperature in this region is around -1,4 degrees Celsius, which facilitates the formation of these new layers of Ice.
This dynamic causes the seafloor to be shaped by a continuous cycle of melting and refreezing, creating a complex and ever-changing landscape.
Craters, mounds and depressions are visible evidence of this activity, where the interaction between variations in water salinity and changes in temperature plays a crucial role.
The impact of ancient climate change
It is important to highlight that the melting of permafrost on the Arctic seabed is not directly related to human-caused climate change, but rather to natural processes that have occurred over millennia.
After the last ice age, sea levels rose and covered large portions of the ancient permafrost that is now slowly thawing due to heat coming from deep within the Earth.
These events have direct implications for the underwater geography of the Arctic. When water from melted permafrost rises and refreezes upon contact with cold seafloor waters, it creates mounds and ridges of ice, while bubbles of water melt the ice sheets, resulting in the formation of large craters.
Long-standing Arctic research
MBARI, together with research institutions from several countries, has been conducting studies in the Arctic since 2003, taking advantage of the retreat of sea ice that has made the area more accessible. In 2010, Canadian researchers mapped the rugged terrain of the seafloor for the first time, and in 2013, MBARI used autonomous underwater vehicles (AUVs) to conduct high-resolution surveys.
Over the course of 12 years, five subsequent surveys revealed the formation of 65 craters, including a massive crater the size of a six-story building block. This underwater volcanic activity is indicative of the dynamic nature of the Arctic seafloor.
In 2022, a new expedition aboard the research icebreaker Araon used MBARI’s AUVs to identify newly formed craters and then visually explore these areas with the MiniROV, a remotely operated vehicle. The images captured revealed the mysterious ice formations inside these craters.
Implications for the Arctic
The researchers’ findings provide a new perspective on underwater permafrost, which was previously seen as a remnant of the last ice age. It is now known that ice formation is still occurring actively under current conditions, challenging previous understanding and requiring adaptation of research tools to accurately map underwater permafrost.
This revelation also poses challenges for public policy and infrastructure development in the Arctic, explains MBARI geologist Charlie Paull. “These dramatic changes in the seafloor have implications for underwater infrastructure in the Arctic,” Paull says. As exploration and development in the region increases, it will be necessary to take into account the ever-changing underwater terrain.
Ice formation from brackish groundwater
The study of ice sheets has revealed that they form from brackish groundwater that, when approaching the surface, freezes again. This phenomenon is responsible for the creation of ice bubbles on the seabed, which eventually form mounds with ice cores covered by sediment.
Isotopic analyses carried out by scientists confirmed that the ice originated from these groundwater sources, which rise due to the thawing of ancient permafrost. Small variations in temperature and salinity can influence the process, alternating between the melting and freezing of different ice layers.
These processes not only alter the underwater landscape, but also raise questions about the location of permafrost across the Arctic shelf. What was once seen as a fixed and stable formation is now revealed to be a dynamic system, subject to constant change.