Progresses in the Impact Study of Arctic Sea Ice Loss on Wintertime Weather and Climate Variability over East Asia and Key Academic Disputes

The Arctic is a crucial region that influences weather and climate over East Asia during the wintertime. The rate of Arctic surface warming is 2-3 times faster than that of the global mean, which is referred to as Arctic amplification. Accompanied by global warming and Arctic sea ice loss, the ecological environment in the Arctic has been changing rapidly. Such changes would possibly influence weather and climate in the mid-and low-latitudes of the Northern Hemisphere. This paper summarizes major advances in the impact study of Arctic sea ice loss on weather and climate in the wintertime. Since 2000, special attention is paid to possible pathways, scientific problems, and key issues in the study of how Arctic sea ice loss affects the wintertime climate variability and extreme cold events.Autumn and winter are freezing seasons when the impact of Arctic sea ice on the atmosphere is stronger than the impact of atmosphere on Arctic sea ice. Over the past two decades, many studies have demonstrated that Arctic sea ice loss not only affects local air temperature and precipitation over the Arctic Ocean, but also influences weather and climate in the mid-and low-latitudes of the Northern Hemisphere due to complicated interactions and feedback processes. Arctic sea ice influences weather and climate over East Asia through two mechanisms:(1) The negative feedback process; (2) the stratosphere-troposphere interaction induced by Arctic sea ice loss. Persistent loss of Arctic sea ice from autumn to winter, particularly in the Barents-Kara Seas, can either enhance the Siberian high or weaken the East Asian winter monsoon. Uncertainties in the impact of Arctic sea ice loss on the wintertime atmosphere can be attributed to the following two reasons:(1) Arctic atmospheric circulation condition in the preceding summer influences the feedback of the persistent less sea ice on the winter atmospheric circulation variability; (2) there exist differences in both the location and strength of wintertime atmospheric response to persistent less sea ice. Under suitable conditions (for example, Arctic atmospheric circulation conditions in the preceding summer are favorable for strengthening the negative feedback of less sea ice), persistent autumn-winter loss of sea ice leads to large-scale wintertime circulation anomalies that favor the occurrence of extreme cold event over Asia.At present, the focuses of disputes in the academic community are mainly concentrated on the following two aspects:(1) The impacts of Arctic warming and Arctic sea ice loss on the mid-latitudes; (2) the reasons for the declining trend in winter surface air temperature over Eurasia since the late 1980s. Indeed, the processes and mechanisms for impacts of Arctic sea ice loss on sub-seasonal variation and extreme cold event over Eurasia still remain unclear, and these problems need to be investigated in the future.