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Do you know how an ice sheet can move? You will find below
Melt water on the Greenland icecap near Camp Victor north of Ilulissat. Photo: SpecialistStoc / REX / Shutterstock
In this warming world, some parts of the planet are warming much faster than others. Warming causes melting of large ice masses and moves quickly, sometimes sliding into the ocean.
This movement is the subject of a brand new scientific study that has just been published in the journal Earth and Planet Science Letters. The Arctic is heating up much faster than other parts of the planet and the ice is showing signs of rapid warming. This fact has serious consequences. First, melting ice can raise sea levels and flood coastal areas – it also makes storms more destructive, such as hurricanes and typhoons. Melting ice also causes a feedback loop, which can lead to greater warming and increased ice loss.
It should be noted that there are different types of ice. A little ice floats on the water and calls the sea ice. When it melts, the level of the ocean water barely moves because the ice is already in the sea and moves liquid water. But sea ice is really important for this feedback loop that I mentioned above.
Another ice is on land and can be a large ice sheet or a smaller glacier. These ice bodies rest on the ground and "rest" there. In some cases, they extend beyond land and into the ocean where they float partly on liquid water. When this ice melts, the liquid flows into the oceans and can cause a significant rise in the level of the oceans.
The importance of ice therefore depends on the type, location and melting speed of the ice. And that brings us to the new paper.
The researchers examined a type of high latitude glacier in their study. These glaciers contain enough water to cause a rise in sea level of about a foot (about a third of a meter). Generally, they exist in cold and dry areas, where snowfall is limited.
How are glaciers moving? Well, either by sliding on the underlying bedrock or the surface on which they are sitting, either by deforming and stretching under their weight. Cooler glaciers tend to move during the process of deformation and stretching. Glaciers that have wetter and more temperate regions involve more slippage. But, whatever the way they move, these glaciers, especially glaciers that have cold and temperate parts, experience blazing movements. These surges are short durations where the glacier moves a lot. During a surge, the ice is redistributed from one part of the glacier to another area.
The authors of this study observed such a glacier surge. This happened on an outlet glacier which is mainly of the "cold" type in Russia. At the Vavilov Ice Cap, on the island of the October Revolution, the authors find that "the acceleration and thinning are extraordinary, but they show no sign of increasing power".
Vavilov's 1820 square kilometer ice cap, with a thickness of 300 to 600 meters, is frozen on its bed in most of its area, with the exception of an area located along of its western margin where basal slip is potentially important.
In 2010, ice in the region began to accelerate and the following year, cracks were observed that corresponded to the patterns of ice acceleration. The researchers were able to observe this ice movement in real time with the help of satellite images. They could follow the movement and show the incredible speed of the flow.
What caused the rapid movement? This is an important issue because if the movement is caused by human warming, one can expect the behavior to be repeated elsewhere as temperatures rise. It is important to note that air and seawater temperatures may be a factor. One of the potential causes is surface melt water. The top of the ice can melt and liquid water can then flow into the ice through cracks and holes. This flowing water can condition the ice for rapid movement.
This fact may be a contributing cause to the motion. Basically, the molten water lubricated the ice / soil interface, which caused more slippage and friction. The friction melted some of the bottom ice and released more liquid water, and a cycle began.
Researchers also took elevation measurements to better understand areas where ice was getting thicker or thinner. In addition, they studied the forces that exist in the ice itself to help elucidate the cause of increased speed. Clearly, this is an evolving area of study and not all questions have been answered yet. However, I was impressed when I read that even though these types of surges were generalizing, what the researchers observed in Russia was still unique. They describe the rate of ice loss in Vavilov as "extreme". The authors also point out
Surprisingly enough, until recently, the Vavilov Ice Cap, an apparently stable ice cap with a bed almost entirely frozen, almost entirely above sea level, could quickly evacuate so much of ice cream in the ocean. period.
So, to answer the question, how fast does it evolve? In 2015, it reached a speed of 82 feet in one day. It currently slides 15 to 35 feet per day. For comparison, it's much faster than the average of 2 inches a day that we would see without power surges.
The message to remember is that once we thought these large expanses of ice were slowly responding to changing conditions. But this research shows us differently. This shows that the ice sheet can move quickly and that once we have crossed a threshold, they can be hard to stop. It is therefore crucial for us to slow global warming before it is too late.
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