Sea ice was once the Arctic Ocean’s “armor”, now “armor” is getting thinner and softer, some have become “light yarn.” Sea ice changes are not isolated events, but triggers a series of changes in the oceans and atmosphere. Researchers and co-researchers from the High-Cold Environmental Quality and Safety Team of the Qinghai-Tibet Plateau Research Institute of the Chinese Academy of Sciences found that Arctic sea ice reduction exacerbates the transport of pollutants such as aerosols to the Qinghai-Tibet Plateau, and the results were published online August 31 in Nature-Climate Change.
Recently, there has been a lot of bad news about the decline of Arctic sea ice: the collapse of Canada’s largest and most complete existing Milne ice shelf, the accelerated melting and disappearance of the Greenland ice sheet, and even scientists predict that Arctic sea ice will disappear within 15 years.
Will Arctic sea ice really be less or less or even disappear? What are the implications of the decline in Arctic sea ice? To this end, the reporter interviewed the relevant experts.
The Arctic may be ice-free by the middle of this century.
One of the most obvious signs of climate change is the Arctic sea ice coverage, which is shrinking dramatically in areas with more than 15 per cent density. September is the month with the least coverage of Arctic sea ice, which has been declining at a rate of 12.9 per cent every 10 years since satellite observations were recorded in 1979. In fact, Arctic sea ice cover has also declined in other months.
“The international mainstream view is that by the middle of this century, the Arctic may be ice-free, i.e. sea ice cover is less than 1 million square kilometers, but without limiting greenhouse gas emissions, the Arctic ice-free state will occur earlier.” Dr. Song Mirong of the Institute of Atmospheric Physics of the Chinese Academy of Sciences told Science and Technology Daily.
The Arctic is warming at two to three times the rate of global warming, and the Arctic’s sea ice is declining. Sea ice older than four years is known by scientists as “multi-year ice”, and studies show that in the 1980s, about a third of the Arctic’s sea ice was multi-year ice.
At the same time, there has been a marked change in the thickness of Arctic sea ice, which used to average 4.88 metres in the past summer and was only about 2.75 metres by the end of the 20th century, a 43 per cent reduction. Since the beginning of the 21st century, Arctic sea ice has retreated much faster than expected.
“As a result, Arctic sea ice will disappear completely in the coming decades.” Song Mirong stressed.
Not long ago, 33 major research institutions around the world presented their outlooks for the area covered by Arctic sea ice in September. Among them, the Chinese Academy of Sciences Institute of Atmospheric Physics Atmospheric Science and Geoflow Mechanics Numerical Simulation of the National Key Laboratory (LASG) submitted values show that in September this year, the sea ice area will be reduced to 3.8 million square kilometers, which will be the second smallest since the observation record, only greater than the record 3.57 million square kilometers in 2012.
Accurate forecasting is still very difficult.
Sea ice area is a measure of the sea ice cover area of Shanghai, sea ice has a high reflectivity, can reflect most of the solar radiation out, so that the polar region to maintain a cold source state, and the size of sea ice area can reflect the amount of solar radiation into the Earth system.
Scientists pay great attention to Arctic sea ice because its changes have a significant impact not only on the local climate, but also on the global atmosphere and oceanic systems. More importantly, polar sea ice and climate change have a significant impact on the climate in the mid- and high-latitude regions, especially in China.
In order to accurately predict the area covered by Arctic sea ice, scientists broke their hearts.
Liu Weiping, a researcher at the Institute of Atmospheric Physics of the Chinese Academy of Sciences, said that Arctic sea ice prediction is becoming more and more important, and based on existing forecasting tools and techniques, it is very difficult to accurately predict sea ice.
An important tool, Liu said, is to make predictions by establishing numerical models, which require historical sea ice, atmospheric and ocean data to create statistical models to predict the spatial distribution of sea ice density, sea ice thickness, and so on. Liu’s team developed a numerical prediction system for Arctic sea ice, which can use a fully coupled Arctic numerical forecasting model of the atmosphere-sea ice-ocean to predict sea ice, with the latest prediction resulting in a minimum Arctic sea ice range of 4.36 million square kilometers in September this year.
In addition, satellite observation is currently the most important means of monitoring Arctic sea ice. “As the satellite crosses the polar region several times a day, the satellite’s advanced microwave scanning radiograph and special sensor microwave imager collect data, analyze and inverse the image of the data formation, and the distribution of polar sea ice intensity can be obtained, and the sea ice area can be calculated.” Song Said.
Liu said that satellite remote sensing has the characteristics of large-scale, real-time and continuous observation, high-resolution satellites, its resolution can reach several hundred meters, which can help researchers to see the morphological evolution of sea ice, can provide more accurate and reasonable initial conditions for the numerical model of sea ice, and thus reduce the simulation deviation of numerical models, improve the prediction ability of Arctic sea ice.
However, at the same time, high-resolution satellite remote sensing in the polar world can only better observe sea ice cover, cloud cover makes high-resolution visible light and near-infrared satellite remote sensing greatly reduced, the sea ice thickness and other conditions of the estimation has a relatively large error.
The decrease in sea ice will trigger a series of changes.
Global warming undoubtedly plays a vital role in reducing Arctic sea ice. However, in addition to global warming, the causes of Arctic sea ice changes are the following factors: increased runoff due to melting of Arctic land glaciers, which significantly affects Arctic ice volumes;
Sea ice was once the Arctic Ocean’s “armor”, now “armor” is getting thinner and softer, some have become “light yarn.” Sea ice changes are not isolated events, but a trigger that can trigger a series of changes in the oceans and atmosphere, which in turn will have far-reaching effects on ecosystems, coastline stability and habitat in cold regions, while further affecting the global climate system, affecting the intensity and frequency of extreme events.
In Song Mirong’s view, the reduction of Arctic sea ice will directly affect the ecological environment of the polar regions. Specific algae and bacteria grow at the bottom of sea ice to feed plankton, which in turn feed larger animals. The reduction of sea ice, especially in the summer, will result in a significant reduction in plankton, which in turn will affect plankton-eating animals. In addition, polar bears, seals, sea ostes, etc. are losing their habitat and being forced to move northwards, while new species such as North Atlantic cod and top predator whales are moving in because they are not covered by sea ice, changing the ecological environment of the polar regions.
If Arctic sea ice disappears completely, in addition to changing the ecological environment of the polar regions, it will also disrupt the global ocean currents, affecting the polar and global weather and climate systems, and freezing greenhouse gases in the Arctic permafrost could be released, exacerbating Arctic warming. The study shows that the changes in the Arctic are closely related to china’s extreme heat, extreme cold, heavy precipitation, blizzards, haze days, as well as high temperature heat waves in Europe, the trend of winter cooling in northern Eurasia, and snowstorms in the northeastern United States. For example, during the accelerated warming phase of the Arctic, the number of cities in the northeastern United States with severe snowstorms increased significantly.
In addition, accelerated warming of the Arctic will lead to further melting of the Greenland ice sheet, resulting in sea level rise, inland inland inland inland inland inland inland irrigation of salt soil, resulting in salinization and marshing of land, and a sharp reduction in the area under cultivation close to coastal areas, resulting in a decline in food production.
As a result, increasingly frequent extreme weather events in the middle and lower latitudes of the densely populated northern hemisphere pose a direct challenge to the safety of human life and property.
The likely good is that routes between the Pacific and Atlantic Oceans through the Arctic Ocean will become frequent. As the world warms, Arctic sea ice is melting, making it increasingly possible for Arctic shipping lanes to open up. The Arctic Seaway consists mainly of the Northeast Passage along the Russian coast, the Central Passage through the central high seas of the Arctic Ocean and the Northwest Passage through the Arctic Archipelago in northern Canada. The Northeast Seaway is currently the main navigation route, in recent years, China has successfully piloted the container ship to take the Northeast Seaway.