Arctic sea ice decreases

What do you think of when it comes to the North Pole? Boundless snow, long winters, white oceans covered by sea ice… For a long time, this vast but sparsely populated area has attracted people’s attention with its beauty and mystery, from ignorance of the North Pole to the opening of the North Pole route. , Here has always inspired the desire of human exploration. In recent years, the Arctic has once again become a hot issue of people’s attention, but this time people are discussing not the fascinating beauty and the unknown, but the worrying reality: the Arctic sea ice area has repeatedly set the lowest record.

The Arctic sea ice continues to decrease, who is the “black hand” behind it?

The North Pole(2021 hermes bags) is one of the vertices of the earth. Humans have paid a great price to discover the truth in this area. The detection methods have also evolved from primitive sled exploration to the use of aircraft mapping, submarines, icebreakers, and unmanned equipment. Since 1979, satellites have become a reliable tool for continuously monitoring changes in Arctic ice. The continuous improvement of observation technology has brought more abundant data, and the fact that the Arctic sea ice is decreasing under the background of global warming is clearly presented to the world: in the past half century, the Arctic has been warming at a rate of about the global Twice the rate of warming. The rapid decline of Arctic sea ice has become a key indicator and “amplifier” of climate change. Climate warming accelerates the melting of sea ice, and the decrease in overall ice reduces the reflected sunlight, which further leads to climate warming.

The long-term and extremely cold climate in the Arctic region has caused the existence of a thick layer of ice that does not change all the year round, called multi-year sea ice. They show their unique beauty with variable shapes and low-key colors. Some Arctic sea ice has obvious seasonal and interannual variability: from August to September each year, the Arctic ice cap will melt to the “minimum value” that scientists call, and as the winter comes, the sea temperature decreases, the Arctic Ocean and its surroundings The sea ice coverage in the sea area will expand, and the sea ice coverage will reach its maximum in March to April of the following year. These sea ice will have an annual cycle with the sea temperature, which will affect the ecosystems around the Arctic and the safety of the Arctic route.

In recent decades, the area of ​​sea ice cover in the Arctic has dropped significantly, which has had a great impact on the flora and fauna and indigenous people that depend on glaciers for life. At the same time, the disappearance of glaciers can also affect more distant regions by changing the climate and weather patterns in mid-latitudes, and ocean circulation. There are still many disputes about the various underlying physical mechanisms and their relative importance that lead to the warming of the Arctic and the melting of sea ice. This is because our earth system is a complex non-linear interacting whole, and various layers can influence each other, such as The constant “stealth” of atmospheric circulation over the ocean is one of the “black hands” behind the reduction of Arctic sea ice in winter.

Weather system that “stretches the whole body”

There are two key areas for the reduction of sea ice in the Arctic in winter: one is the high latitudes of North America (Baffin Bay, Hudson Strait and Labrador Sea hermes outlet); the other is near the Barents Sea-Kara Sea. Among them, the Barents Sea-Kara Sea is one of the origins of cold waves in Eurasia and a key sea area that affects the cold air activity in Eurasia in winter. In recent years, extreme strong cold wave events have occurred frequently in the mid-latitudes of the northern hemisphere. Many scholars believe that the rapid reduction of sea ice in the Barents Sea-Kara Sea has triggered the adjustment of atmospheric circulation to affect mid-latitudes.

In the westerly zone of the northern hemisphere, atmospheric motion is not a straight line, but undulating. The crests that bulge northward are called high-pressure ridges, and the troughs of depressions to the south are low-pressure troughs. In front of the back ridge”) generally the northeast wind brings dry and cold air.

Sometimes during the development and evolution of the westerly trough and ridge, the ridge continues to extend northward, and its connection with the warm air in the south is cut off by the cold air, so an isolated closed center of warm high pressure appears on the north side of the ridge. It often lasts longer and rarely moves, hindering the upstream weather system in the westerly belt from moving eastward, so it is called “blocking high”. The formation,replica hermes and collapse of the blocking high in the northern hemisphere play a very important role in our country’s weather and climate: the collapse of the Ural Mountain blocking high often causes a wide range of cold waves in East Asia. The maintenance of the Okhotsk blocking high is an important major cause of the Meiyu in my country. Scale circulation conditions.

The blocking high is one of the most important weather systems in the middle and high latitudes of the northern hemisphere. Its establishment and collapse are often accompanied by a dramatic change in the form of a large-scale or even hemispherical circulation. The Rodhai team of the Institute of Atmospheric Physics has conducted a series of studies on the relationship between the Ural obstructive high pressure and Arctic sea ice in winter. Their results show that the meridional temperature gradient and westerly wind in the middle and high latitudes of Europe and Asia decrease under the background of increasing Arctic temperature , Resulting in a reduction in the meridional potential vorticity (2021 hermes bags) gradient. Under this circulation background, the Ural block will show a quasi-steady (non-moving) characteristic, and its continuity will also become longer. The slow-moving blocking high pressure entrenched over the Ural Mountains and Novaya Zemlya Island has caused a long-lasting reduction in sea ice through downward long-wave radiation. The drastic reduction of the Barents-Kara Sea ice in the last two decades may be related to the maintenance of the quasi-steady Ural blockage. related. At the same time, the west side of the Ural Blocking Circulation cooperates with the sea level pressure field in the upstream North Atlantic Ocean, which is conducive to transporting warm and humid water vapor from low latitudes to the North Pole, resulting in a continuous decrease in sea ice in the Barents Sea-Kara Sea region; the Ural Blocking Circulation east On the other hand, the cold air from high latitudes is continuously transported to the mid-latitudes of Europe and Asia, which significantly increases the frequency of extreme cold events in this region.

Scientists’ findings indicate that there is a correlation between sea ice reduction and extreme winters in mid-latitudes, but this does not mean that one directly caused the other, but that both are simultaneously affected by the same large-scale atmospheric circulation. The interaction between the various layers of the earth is somewhat similar to the “chicken and egg traceability”. Perhaps the reduction of Arctic sea ice is not the direct cause of the cold winter in Asia, but the reduction of sea ice coverage under the influence of atmospheric circulation means the increase of open water area. Let the ocean release more heat to the atmosphere in winter, which will further change the atmospheric circulation and may make cold winters more frequent and severe. With the increasing severity of global warming issues, it is more important to understand the changes in the overall Arctic Ocean sea ice and various sea areas, as well as the laws of ocean-sea ice-atmosphere correlation. A few days ago, the “China Highly Cited Article Award” announced by the IOP Publishing House includes an article by the Institute of Atmospheric Research Researcher Rod Hai and his collaborators on the Arctic sea ice reduction series of research articles on Atmospheric circulation patterns which promote winter Arctic sea The ice decline is one of only two highly cited papers in the field of environmental science. This article was published in the journal Environmental Research Letters in 2017.

The tripolar regions (the Arctic, Antarctica, and the Qinghai-Tibet Plateau) are more affected by climate change than the global average. Under the action of a short period of cold air, the waters freeze again, but the new ice layer is thinner and more fragile. When the temperature rises slightly, it will cause new “large openings.” The thinning sea ice reduces the stability of the sea ice system and is more fluid. As the speed of movement increases, the ice layer is easier to enter the warmer ocean and then melt. What happened thousands of miles away is not nothing to do with us. How does the rapid decline of sea ice range relate to the extreme cold wave events in Asia? Will it cause other extreme weather to appear? All this is still unknown.