Since 1984, scientists have been working on estimates of the sea ice age and its age evolution in order to understand the mysteries behind the ice thickness across the Arctic, as direct measurements often fail to reflect its exact characteristics.
According to the researchers, the sea ice has grown, shrunk, spun, melted and drifted out of the Arctic during the last three decades, as shown by a NASA visualization of the age of Arctic sea ice.
During the first years of the 21st century, researchers at the University of Colorado created a way to monitor the Arctic sea ice movement, as well as its evolution in age, through the use of data from a corroboration of sources, mainly satellite passive microwave instruments.
Thus, brightness temperature was shown; according to the scientists, the ice's thickness is directly proportional to its age.
"Ice age is a good analog for ice thickness because basically, as ice gets older it gets thicker. This is due to the ice generally growing more in the winter than it melts in the summer," noted Walt Meier, a NASA sea ice researcher.
The instruments used by the researchers measured the microwave energy that the sea ice emitted, as well as the influence on the ice temperature, the ice salinity level, the texture of the ice surface and, ultimately, the layer of snow that lies on top of the sea ice.
Each year, the ice is created during the winter and it melts during the summer. However, the ice layer that manages to survive the hot season thickens from one year to another. Consequently, this starts a natural slippery slope. The more ice remains after the hot season, the thicker the ice layer during the cold season, and the thicker it becomes, the harder it is for it to melt.
During one single year, the ice grows from 3 to 7 feet in thickness; however, multi-year ice, the one that manages to remain unmelted throughout more seasons in a row, is roughly 10 to 13 feet thick. However, despite this natural trend of growing in thickness, the sea ice has become thinner and younger during the past years.
According to Meier, this bizarre and threatening phenomenon is caused by sea ice melting from one season to another. While the sea ice formed throughout various seasons should be more resistant to melting, it seems that it behaves very similarly to the current year's ice layer. Consequently, the old ice melts along with the new one during the hot seasons.
One of the main reasons causing this occurrence could be the ice formation and its dynamic. Unlike the past, when ice layers were seen in huge, resistant blocks, the current ice layers can be observed in much smaller chunks, which makes them more vulnerable to melting during the hot season.
