The decrease of the ice cover during the last 90 thousand years was in proportion with climate change. This is evidenced by a new study, the results of which are presented in New Communications.
Arctic ice is quickly responded to recent climate change. During the coldest periods within the last 90 thousand years, the ice edge of sea ice relatively quickly moved to Grislawski Scottish mountains, and perhaps far into the Atlantic ocean, ” says lead author of the project, researcher at the Centre for the study of Arctic gas hydrate, environment and climate Ulrik Hoff.
Sea ice amplifies climate change, exerting a huge impact on the marine environment, water circulation, ice growth and migration. Hoff and his colleagues investigated the distribution of sea ice as of its formation on the basis of the sample that was extracted from a depth of 1200 metres in the Faeroe Islands. He can best help to study the changes of sea ice and climate in the past.
In these layers lies a tiny proof that sea ice behaves differently depending on the light. A role is played by the type of phytoplankton, called diatoms, which lives all around us.
Organisms diatoms — unicellular algae with a single cell wall composed of silica. You can see this substance Golden brown in the glass street lamps, and those are sequins that women applied to the face, making the makeup. They even used in toothpaste as a cleaning substance. Diatoms are amazing. They were able to remain in the marine and lacustrine deposits, formed over millions of years. I personally researched diatomie fossils which are 65 million years, and they are preserved in the same form as those that exist today, ” explains Hoff.
Not only Hoff and his colleagues, studied the diatoms, saying that the North sea was covered with ice. Moreover, with this method it is possible to determine the ice thickness and whether its existence is a seasonal phenomenon or a permanent one.
Sea ice sharply reduced in times of warming and rapidly spread during the phases of cooling, becoming perennial encyclopedia journey through the cold periods. Some types of diatomaceous made sea ice is their habitat, attaching itself to him. If you dive under the ice crust, they can be seen is the Golden brown layer which they form. However, being in origin of algae, their life depends on the sun’s rays that penetrate through the ice, including the process of photosynthesis. If the ice is too thick, the sun does not reach them and their number decreases rapidly. “Classifying diatoms in certain parts of the kernel by counting them, we were able to identify their content and to assess the thickness of the ice. By doing this, you need to consider that, wilt, diatomite sediments under the influence of salty sea water becomes very brittle. Ocean water quickly fills the void with silicon and they dissolve.
When they fall to the bottom of the ocean, and secrete a specific substance, called IP25. Is a molecule that is not soluble in sea water easily. Testing – to detect the presence of this substance, scientists were able to determine whether there are components of diatoms in the ocean, and how well developed this population.
We first have a strong and detailed argument that sea ice was distributed in the Northern seas, because of the presence of IP25. Our previous studies in different areas of the Nordic seas and the North Atlantic ocean could only give us the opportunity to conclude that sea ice existed there, — the co-author of the theory Tina Rasmussen.
Rasmussen notes that sea ice has a significant influence on the behavior of ocean currents, which, in turn, affect air temperature. For example, the eternal sea-ice cover will negatively affect deepwater formation such as the Gulf stream.
Understanding of the influence of sea ice on climate change and the formation of ocean currents in the past, will help us to understand how these processes will develop in the future, ” explained Professor Rasmussen.