In recent years, different scientific research teams have put forward many different views on the Arctic amplification effect.
For example, the increase in Arctic cloud cover and water vapor causes more long-wave radiation to be reflected back to the sea or ice; mid-latitudes transport more heat and water vapor to the North Pole through fluctuations and atmospheric circulation; ocean warming transports more heat to the poles, causing sea ice to melt; The loss of ozone in the polar regions may have contributed to the extreme increase in temperature in the Arctic.
At present, global warming has repeatedly aroused people's discussion.
Due to people burning petroleum, coal and other fossil fuels, cutting down forests and burning them, a large number of greenhouse gases such as carbon dioxide are produced. These greenhouse gases are highly transparent to visible light from solar radiation and are highly transparent to long-wave radiation emitted by the earth. Absorptive, can strongly absorb infrared radiation from the ground, causing the earth's temperature to rise.
In the context of global warming, the temperature increase in the Arctic seems to be more "dead" compared to most other parts of the world:
In recent years, high temperature abnormalities have frequently occurred in the Arctic region.
For example, on July 30, 2018, the Norwegian city of Barnack, located 250 kilometers within the Arctic Circle, experienced a high temperature of 32°C; on July 4, 2019, the National Weather Service released data showing that Anchorage International in Alaska The temperature at the airport reached 32°C, breaking the 50-year high temperature record; on June 20, 2020, Siberia Verkhoyansk monitored a high temperature of 38°C, setting a new high temperature record in the Arctic.
Studies have shown that from December 2015 to February 2016, the Arctic surface temperature was 0.7°C higher than the last warmest record (Winter 2011-2012). The National Oceanic and Atmospheric Administration (NOAA) data report shows that in 2018 From October to September 2019, the average temperature in the Arctic rose again by 1.9°C.
Recently, a climate science team has even reported that the Arctic is warming at four times the global average rate.
Is this statement true?
What is causing the Arctic's warming rate to be higher than the global average rate?
The Arctic amplification effect makes the Arctic heat up faster
Previous studies have shown that in decades, the Arctic has increased by as much as 1.2°C per 10 years, which is the region where the global surface temperature has increased the most. The increase is more than twice the global average. This phenomenon is called It is the amplification effect of the Arctic.
The Arctic plays an important modulating role in the climate system.
With the increase of global carbon emissions, the global warming effect is significant. Arctic sea ice melts sharply, the density, range, and thickness of sea ice decrease, and there is a trend of conversion from perennial ice to seasonal sea ice, which in turn triggers a series of changes. climate change.
Because of this, the amplification effect of the Arctic has attracted much attention. Countries and meteorological organizations in the world are paying great attention to the changes in Arctic temperature.
Why is there an enlargement of the North Pole?
In recent years, different scientific research teams have put forward many different views.
For example, the increase in Arctic cloud cover and water vapor causes more long-wave radiation to be reflected back to the sea or ice; mid-latitudes transport more heat and water vapor to the North Pole through fluctuations and atmospheric circulation; ocean warming transports more heat to the poles, causing sea ice to melt; The loss of ozone in the polar regions may have contributed to the extreme increase in temperature in the Arctic.
"The driving mechanism of Arctic amplification is very complicated." said Wang Haicheng, professor and director of the Gansu Key Laboratory of Climate Resources and Disaster Prevention and Mitigation. Existing studies have shown that local factors are mainly affected by sea ice albedo feedback, clouds and water vapor Feedback, Planck feedback of atmospheric temperature, etc.
In terms of heat transport outside the Arctic, it includes the transport of ocean circulation to extreme heat, and the modulation of sea temperatures in the Atlantic and Pacific Oceans.
In addition, some people have also proposed that changes in the early vegetation greening period, the extension of the growing season, and the increase of vegetation greenness in the Arctic circum-Arctic land area will also have a feedback effect on the warming of the Arctic.
Regarding the interpretation of the Arctic amplification effect, Chen Jinlei, a researcher at the State Key Laboratory of Cryosphere Science, Northwest Institute of Eco-Environmental Resources, Chinese Academy of Sciences, most recognized the "positive feedback process within the Arctic."
Chen Jinlei said that the underlying surface of the Arctic is mainly ocean and sea ice. The albedo of ice is 30%-70%, and the albedo of water is only 20%-30%. The albedo of ice is much larger than that of water.
Affected by global warming, the thickness and coverage of sea ice have decreased, resulting in an increase in the absorption of solar radiant energy by the ocean, and the warming of sea water has further aggravated the melting of sea ice.
More and more open seas are also heating up the atmosphere.
Temperature measurement is not simple
Scientists have reached a consensus that the Arctic temperature is growing faster than the global average, but how did this conclusion come about?
Where is the temperature determined by the temperature?
For temperature measurement, a denser network of ground meteorological observation stations and high-altitude weather observation stations have been established around the world.
The World Meteorological Organization's "Global Observing System Guide" stipulates that the environment of the observation site should have typical physical, chemical and geographic characteristics.
The observation site should also meet the "Ground Meteorological Observation Specifications."
"For example, the site of the meteorological observation instrument should be selected in an open area away from buildings and trees, and the distance from the buildings and trees to the observation area should be at least 10 and 20 times the height of the building or tree itself, respectively. In addition to shore-based observations, the distance between the observation point and the water body should be more than 100 meters. Therefore, an observation site should represent the average temperature within a larger range." Wang Haicheng said.
Chen Jinlei analyzed that in the newly released report, researchers believe that the Arctic is warming 4 times faster than other regions, for several reasons.
The first is that its definition of the Arctic region is different.
In previous studies, the north of 60 degrees north latitude was regarded as the North Pole. In this study, the researchers believe that the arctic range should be defined strictly in accordance with the Arctic Circle, which is 66.6 degrees north latitude.
In theory, this division will increase the magnification.
The large time span is also one of the reasons why the report reached this conclusion.
Chen Jinlei believes that the time span used to calculate warming is very important. The new report selects the past 30 years for research, but the past 30 years have been the most significant stage of global warming.
"Another reason is that the various data used by everyone are not uniform." Chen Jinlei said, to determine the temperature, the observation is of course the most accurate, but the world does not have such a dense observation network, so everyone generally uses reanalysis data and remote sensing. Data. There are many types of data released by different institutions and different temporal and spatial resolutions, so the final results are also inconsistent.
"This conclusion has not yet reached a consensus in the academic community." Chen Jinlei believes that the speed of the Arctic warming is 2 to 3 times that of the global average. The current accepted data is 2 to 3 times. The Arctic Council Arctic Monitoring and Evaluation Working Group (AMAP) report in 2021 In, this data is 3 times.
The influence of accelerated polar heat cannot be underestimated
Does Antarctica, which is also a polar region, have an Antarctic amplification effect?
"Studies have shown that temperature rises have also occurred in the Antarctic region." Wang Haicheng said, but the research suggests that the surface of Antarctica is warming rapidly in West Antarctica, while East Antarctica has a cooling trend in summer and autumn in the Southern Hemisphere.
Some scholars’ analysis shows that between 1989 and 2018, the surface temperature in Antarctica rose by 1.8°C, which was three times the temperature increase in other parts of the world.
Many studies have shown that temperature changes in Antarctica are related to tropical sea temperatures, and ocean temperature changes in the western Pacific Ocean in tropical regions have a great impact on Antarctic warming. Changes in atmospheric circulation will cause more warm air to be transported to the Antarctic continent.
From this perspective, the warming of the Antarctic also has a similar performance to the amplification effect of the Arctic.
Whether it is the Arctic warming rate that the research team believes is four times that of other regions or two to three times the academic world's recognized warming, the polar warming will undoubtedly bring complex and potential impacts on the earth and humans.
Chen Jinlei said that for the Arctic, on the one hand, under the influence of sea ice melting, the Arctic waterway is expected to be opened, which will greatly reduce the distance from Northeast Asia to Europe and North America, and at the same time help the development and utilization of local Arctic resources.
But for the local biological environment, the accelerated warming of the polar regions will have adverse effects. For example, polar bears that need to breed and rest on sea ice will have no place.
The melting of sea ice will also cause global sea levels to rise. The fresh water released in this process will flow into the Atlantic Ocean through ocean circulation, which will change the salinity of these sea areas and further affect the weather, climate, and fisheries.
The Arctic and adjacent areas are therefore prone to extreme weather and climate events, including high temperature events and other extreme low temperature events such as heavy precipitation and snowstorms.
Chen Jinlei gave an example. For example, the cold current hit Texas in the United States last year and the freezing rain in southern my country in 2008 were all caused by the warming of the Arctic.
Wang Haicheng emphasized that research has also shown that the frequent occurrence of extreme cold in winter in recent years has a clear correlation with the warming effect of the polar regions.
Changes in polar temperature have also changed the atmospheric circulation, which has an important impact on the transportation direction of dust and haze.
Issues that need to be further confirmed include the impact of polar warming on sea storms, summer heat, and autumn precipitation.