New Mechanisms of Polar Amplification Triggered by the Arctic Sea Ice Loss

The effect of positive feedbacks is associated with the phenomenon of the so-called Polar amplification, due to which an increase of the surface air temperature in the Arctic in recent decades was approximately 2.5 times higher than in the other latitudinal zones. Reduction of the Arctic sea ice acted as a “trigger” that provided an intensification of feedbacks, which were either not manifested at all or were ineffective under the conditions of the prevalence of thick consolidated ice. In addition to the well-known and described in the literature feedbacks that are acting in high latitudes, two new mechanisms are introduced: “seasonal memory” in the ice cover properties and “atlantifi- cation”. It has been shown that these mechanisms contribute to the further reduction of the Arctic sea ice. In the East-Atlantic sector of the Arctic Ocean both mechanisms operate in concert, enhancing the end result. According to climate scenarios, Arctic warming is projected to intensify in the coming decades, causing changes in various environments. It can be expected that an important role in this will be played by positive feedbacks that provide the Polar amplification in modern conditions, when the Arctic climate system is in an unstable transitional state.