Among them, the data submitted by the State Key Laboratory of atmospheric science and geohydrodynamics numerical simulation of Institute of Atmospheric Physics of Chinese Academy of Sciences (LASG) shows that the sea ice area will be reduced to 3.8 million square kilometers in September, which will be the second smallest value of sea ice area since the observation record, only larger than the record of 3.57 million square kilometers in 2012. Recently, 33 major research institutions in the world submitted the Arctic sea ice area outlook in September, including 16 numerical model prediction results, 14 statistical prediction results and 3 qualitative analysis results, but the results submitted by various institutions are quite different. According to Wei Ke, associate researcher of the Institute of Atmospheric Physics, Chinese Academy of Sciences, the forecast value submitted by the University of Washington is the smallest, only 3.2 million square kilometers; the second is the Geophysical Fluid Dynamics Laboratory of the National Oceanic and Atmospheric Administration, with a forecast value of 3.5 million square kilometers; and the prediction value submitted by LASG is 3.8 million square kilometers They are all below 4 million square kilometers, far below the median range of all models. However, the predictions made by the US Naval Research Laboratory espc system, Norway’s metno sparse and France’s apply cnrm are significantly higher than the median range of all models. For example, the predicted value of espc system is 6.2 million square kilometers. In this regard, Liu Jiping, a professor at State University of New York, pointed out that the Siberian heat wave this spring caused the sea ice along the Russian coast to retreat earlier, resulting in a very small sea ice range in the Laptev Sea and the Barents Sea. At the same time, in the summer of this year, abnormal high temperature appeared in the Arctic. For example, on June 20, the maximum daytime temperature in verkhoyansk, Siberia, Russia, reached 38 ℃. < / P > < p > this is a rare value because the highest temperature in this area at the same time in history was only 22 ℃. It is not ruled out that the Arctic sea ice area in September this year tends to be “less than 4 million square kilometers”. < p > < p > sea ice reflects up to 80% of the incident sunlight, which plays a cooling role. The size of sea ice modulates the amount of sunlight entering the earth system. < p > < p > when the temperature increases due to climate change, the sea ice ablation will be intensified. The sunlight incident in polar days can enter the ocean more, and the seawater will absorb more heat, and the temperature will rise faster, which will lead to more large-scale sea ice melting. < / P > < p > in the process of global warming, the Arctic region’s warming amplitude can reach more than twice the global average, which is called “Arctic amplification” phenomenon, which will aggravate global warming and the melting of Arctic sea ice. < p > < p > on September 25, 2019, the United Nations Intergovernmental Panel on Climate Change released the special report on oceans and cryosphere in climate change, which evaluated the latest changes, impacts and adaptation strategies of the oceans and cryosphere, reflecting the latest understanding of the ocean and cryosphere in the scientific community. < p > < p > the report points out that global ocean and cryosphere changes are accelerating. During the period from 1979 to 2018 with satellite observation, the Arctic sea ice range in September decreased rapidly at the rate of 12.8% every 10 years. At present, the sea ice range is the minimum value in at least 1000 years. As the “indicator and amplifier” of global climate change, the health and stability of the global cryosphere is the cornerstone of the stability of the climate system. Its rapid ablation will inevitably have a profound impact on the ecosystem, coastal stability and human settlements in alpine regions, and will further modulate the global climate system and affect the intensity and frequency of extreme events. For example, polar bears, walruses and whales rely on sea ice to maintain their hunting, breeding and migration habits. A significant reduction in sea ice will have a profound impact on the Arctic ecosystem. < / P > < p > “the abnormal changes of Arctic sea ice range and area will have a profound impact on navigation safety and the ecosystem around the Arctic, as well as on the evolution of atmospheric circulation in the middle and low latitudes and the occurrence of extreme weather and climate events.” Ren pointed out. The prediction of Arctic sea ice can provide scientific basis and reference for global climate change monitoring, Arctic waterway utilization, Arctic resource development, and Arctic environment assessment. < / P > < p > “now the prediction of Arctic sea ice is becoming more and more important. We need the means and technology that can accurately predict the Arctic sea ice. However, the prediction of sea ice is very difficult Liu Jiping stressed. < p > < p > he said that in order to do a good job in forecasting, it is necessary to establish a very complex numerical model, which includes atmosphere, sea ice and ocean, etc. it is necessary to consider the interaction between them, solve a series of very complex mathematical and physical equations, and then make predictions. < / P > < p > “we mainly use models to forecast Arctic sea ice. The China multi-mode ensemble forecasting system (CMME) of China Meteorological Administration can release the operational products of Arctic sea ice forecast every month.” Ren Hongli said. Another method is satellite remote sensing. Liu Jiping pointed out that only high-resolution satellites can see the evolution of sea ice morphology and provide short-term monitoring of sea ice. However, high resolution satellite remote sensing is facing great challenges in polar regions. Cloud covered sea ice monitoring greatly reduces the effect of high-resolution visible light and near-infrared satellite remote sensing; microwave satellite remote sensing can penetrate clouds, but the resolution is low. According to Wei Ke, it is necessary to formulate reasonable policies and measures, carry out long-term emission reduction and short-term climate change adaptation to cope with the impacts and risks of climate change.